DERIVATION AND VALIDATION OF A MACHINE LEARNING MODEL FOR THE PREVENTION OF UNPLANNED DIALYSIS

BACKGROUND

Approximately half of all patients with advanced chronic kidney disease (CKD) who progress to kidney failure initiate dialysis in an unplanned fashion which is associated with high morbidity, mortality, and healthcare costs. A novel prediction model designed to identify advanced CKD patients who are at high risk for developing kidney failure over short time frames (6-12 months) may help reduce the rates of unplanned dialysis and improve the quality of transitions from CKD to kidney failure.

METHODS

We performed a retrospective study employing machine learning random forest algorithms incorporating routinely collected age and sex data along with time-varying trends in laboratory measurements to derive and validate six- and 12-month kidney failure risk prediction models in the advanced CKD population. The models were comprehensively characterized in three independent cohorts in Ontario, Canada - derived in a cohort of 1,849 consecutive advanced CKD patients (mean [standard deviation] age 66 [15] years, eGFR 19 [7] mL/min/1.73m2), and validated in two external advanced CKD cohorts (n=1,356; age 69 [14] years, eGFR 22 [7] mL/min/1.73m2).

RESULTS

Across all cohorts, 55% of patients experienced kidney failure, of which 35% involved unplanned dialysis. The six- and 12-month models demonstrated excellent discrimination with area under the receiver operating characteristic curve of 0.88 (95%CI: 0.87-0.89) and 0.87 (95%CI: 0.86-0.87) along with high probabilistic accuracy with Brier scores of 0.10 (95%CI 0.09-0.10) and 0.14 (95%CI 0.13-0.14), respectively. The models were also well-calibrated and delivered timely alerts on a significant number of patients who ultimately initiated dialysis in an unplanned fashion. Similar results were found upon external validation testing.

CONCLUSION

These machine-learning models using routinely collected patient data accurately predict near-future kidney failure risk among the advanced CKD population, and retrospectively deliver advanced warning on a substantial proportion of unplanned dialysis events. Optimal implementation strategies still need to be elucidated.

Perceptions and Information-Seeking Behavior Regarding COVID-19 Vaccination Among Patients With Chronic Kidney Disease in 2023: A Cross-Sectional Survey

Background

People living with chronic kidney disease (CKD) face an increased risk of severe outcomes such as hospitalization or death from COVID-19. COVID-19 vaccination is a vital approach to mitigate the risk and severity of infection in patients with CKD. Limited information exists regarding the factors that shape COVID-19 vaccine uptake, including health information-seeking behavior and perceptions, within the CKD population.

Objective

The objectives were to describe among CKD patients, (1) health information-seeking behavior on COVID-19, (2) their capacity to comprehend and trust COVID-19 information from different sources, and (3) their perceptions concerning COVID-19 infection and vaccination.

Design/Setting

Cross-sectional web-based survey administered in British Columbia and Ontario from February 17, 2023, to April 17, 2023.

Participants

Chronic kidney disease G3b-5D patients and kidney transplant recipients (CKD G1T-5T) enrolled in a longitudinal COVID-19 vaccine serology study.

Methods and Measurements

The survey consisted of a questionnaire that included demographic and clinical data, perceived susceptibility of contracting COVID-19, the ability to collect, understand, and trust information on COVID-19, as well as perceptions regarding COVID-19 vaccination. Descriptive statistics were used to present the data with values expressed as count (%) and chi square tests were performed with a significance level set at P ≤ .05. A content analysis was performed on one open-ended response regarding respondents' questions surrounding COVID-19 infection and vaccination.

Results

Among the 902 patients who received the survey via email, 201 completed the survey, resulting in a response rate of 22%. The median age was 64 years old (IQR 53-74), 48% were male, 51% were university educated, 32% were on kidney replacement therapies, and 57% had received ≥5 COVID-19 vaccine doses. 65% of respondents reported that they had sought out COVID-19-related information in the last 12 months, with 91% and 84% expressing having understood and trusted the information they received, respectively. Those with a higher number of COVID-19 vaccine doses were associated with having sought out (P =.017), comprehended (P < .001), and trusted (P =. 005) COVID-19-related information. Female sex was associated with expressing more concern about contracting COVID-19 (P = .011). Most respondents strongly agreed to statements regarding the benefits of COVID-19 vaccination. Respondents' questions about COVID-19 infection and vaccination centered on 4 major themes: COVID-19 vaccination strategy, vaccine effectiveness, vaccine safety, and the impact of COVID-19 infection and vaccination on kidney health.

Limitations

This survey was administered within the Canadian health care context to patients with CKD who had at least 1 COVID-19 vaccine dose. Race/ethnicity of participants was not captured.

Conclusions

In this survey of individuals with CKD, COVID-19 information-seeking behavior was high and almost all respondents understood and trusted the information they received. Perceptions toward the COVID-19 vaccine and booster were mostly favorable.

The Association of Intra-Abdominal Adhesions with Peritoneal Dialysis Catheter-Related Complications

BACKGROUND

This study investigated the association of intra-abdominal adhesions with the risk of peritoneal dialysis (PD) catheter complications.

METHODS

Individuals undergoing laparoscopic PD catheter insertion were prospectively enrolled from eight centers in Canada and the United States. Patients were grouped based on the presence of adhesions observed during catheter insertion. The primary outcome was the composite of PD never starting, termination of PD, or the need for an invasive procedure caused by flow restriction or abdominal pain.

RESULTS

Seven hundred and fifty-eight individuals were enrolled, of whom 201 (27%) had adhesions during laparoscopic PD catheter insertion. The risk of the primary outcome occurred in 35 (17%) in the adhesion group compared with 58 (10%) in the no adhesion group (adjusted HR, 1.64; 95% confidence interval [CI], 1.05 to 2.55) within 6 months of insertion. Lower abdominal or pelvic adhesions had an adjusted HR of 1.80 (95% CI, 1.09 to 2.98) compared with the no adhesion group. Invasive procedures were required in 26 (13%) and 47 (8%) of the adhesion and no adhesion groups, respectively (unadjusted HR, 1.60: 95% CI, 1.04 to 2.47) within 6 months of insertion. The adjusted odds ratio for adhesions for women was 1.65 (95% CI, 1.12 to 2.41), for body mass index per 5 kg/m 2 was 1.16 (95% CI, 1.003 to 1.34), and for prior abdominal surgery was 8.34 (95% CI, 5.5 to 12.34). Common abnormalities found during invasive procedures included PD catheter tip migration, occlusion of the lumen with fibrin, omental wrapping, adherence to the bowel, and the development of new adhesions.

CONCLUSIONS

People with intra-abdominal adhesions undergoing PD catheter insertion were at higher risk for abdominal pain or flow restriction preventing PD from starting, PD termination, or requiring an invasive procedure. However, most patients, with or without adhesions, did not experience complications, and most complications did not lead to the termination of PD therapy.

Impact of Prior Abdominal Procedures on Peritoneal Dialysis Catheter Outcomes: Findings From the North American Peritoneal Dialysis Catheter Registry

RATIONALE & OBJECTIVE

A history of prior abdominal procedures may influence the likelihood of referral for peritoneal dialysis (PD) catheter insertion. To guide clinical decision making in this population, this study examined the association between prior abdominal procedures and outcomes in patients undergoing PD catheter insertion.

STUDY DESIGN

Retrospective cohort study.

SETTING & PARTICIPANTS

Adults undergoing their first PD catheter insertion between November 1, 2011, and November 1, 2020, at 11 institutions in Canada and the United States participating in the International Society for Peritoneal Dialysis North American Catheter Registry.

EXPOSURE

Prior abdominal procedure(s) defined as any procedure that enters the peritoneal cavity.

OUTCOMES

The primary outcome was time to the first of (1) abandonment of the PD catheter or (2) interruption/termination of PD. Secondary outcomes were rates of emergency room visits, hospitalizations, and procedures.

ANALYTICAL APPROACH

Cumulative incidence curves were used to describe the risk over time, and an adjusted Cox proportional hazards model was used to estimate the association between the exposure and primary outcome. Models for count data were used to estimate the associations between the exposure and secondary outcomes.

RESULTS

Of 855 patients who met the inclusion criteria, 31% had a history of a prior abdominal procedure and 20% experienced at least 1 PD catheter-related complication that led to the primary outcome. Prior abdominal procedures were not associated with an increased risk of the primary outcome (adjusted HR, 1.12; 95% CI, 0.68-1.84). Upper-abdominal procedures were associated with a higher adjusted hazard of the primary outcome, but there was no dose-response relationship concerning the number of procedures. There was no association between prior abdominal procedures and other secondary outcomes.

LIMITATIONS

Observational study and cohort limited to a sample of patients believed to be potential candidates for PD catheter insertion.

CONCLUSION

A history of prior abdominal procedure(s) does not appear to influence catheter outcomes following PD catheter insertion. Such a history should not be a contraindication to PD.

PLAIN-LANGUAGE SUMMARY

Peritoneal dialysis (PD) is a life-saving therapy for individuals with kidney failure that can be done at home. PD requires the placement of a tube, or catheter, into the abdomen to allow the exchange of dialysis fluid during treatment. There is concern that individuals who have undergone prior abdominal procedures and are referred for a catheter might have scarring that could affect catheter function. In some institutions, they might not even be offered PD therapy as an option. In this study, we found that a history of prior abdominal procedures did not increase the risk of PD catheter complications and should not dissuade patients from choosing PD or providers from recommending it.

The impact of the Starting dialysis on Time, At home on the Right Therapy (START) project on the use of peritoneal dialysis

BACKGROUND

Peritoneal dialysis (PD) is actively promoted, but increasing PD utilisation is difficult. The objective of this study was to determine if the Starting dialysis on Time, At Home, on the Right Therapy (START) project was associated with an increase in the proportion of dialysis patients receiving PD within 6 months of starting therapy.

METHODS

Consecutive patients over age 18, with end-stage kidney failure, who started dialysis between 1 April 2015 and 31 March 2018 in the province of Alberta, Canada. Programmes were provided with high-quality data about the individual steps in the process of care that drive PD utilisation that were used to identify problem areas, design and implement interventions to address them, and then evaluate whether those interventions had impact. The primary outcome was the proportion of patients receiving PD within 6 months of starting dialysis. Secondary outcomes included hospitalisation, death or probability of transfer to haemodialysis (HD). Interrupted time series methodology was used to evaluate the impact of the quality improvement initiative on the primary and secondary outcomes.

RESULTS

A total of 1962 patients started dialysis during the study period. Twenty-seven per cent of incident patients received PD at baseline, and there was a 5.4% (95% confidence interval: 1.5-9.2) increase in the use of PD in the province immediately after implementation. There were no changes in the rates of hospitalisation, death or probability of transfer to HD after the introduction of START.

CONCLUSIONS

The approach used in the START project was associated with an increase in the use of PD in a setting with high baseline utilisation.

Humoral Response Following 3 Doses of mRNA COVID-19 Vaccines in Patients With Non-Dialysis-Dependent CKD: An Observational Study

Background

Chronic kidney disease (CKD) is associated with a lower serologic response to vaccination compared to the general population. There is limited information regarding the serologic response to coronavirus disease 2019 (COVID-19) vaccination in the non-dialysis-dependent CKD (NDD-CKD) population, particularly after the third dose and whether this response varies by estimated glomerular filtration rate (eGFR).

Methods

The NDD-CKD (G1-G5) patients who received 3 doses of mRNA COVID-19 vaccines were recruited from renal clinics within British Columbia and Ontario, Canada. Between August 27, 2021, and November 30, 2022, blood samples were collected serially for serological testing every 3 months within a 9-month follow-up period. The severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) anti-spike, anti-receptor binding domain (RBD), and anti-nucleocapsid protein (NP) levels were determined by enzyme-linked immunosorbent assay (ELISA).

Results

Among 285 NDD-CKD patients, the median age was 67 (interquartile range [IQR], 52-77) years, 58% were men, 48% received BNT162b2 as their third dose, 22% were on immunosuppressive treatment, and COVID-19 infection by anti-NP seropositivity was observed in 37 of 285 (13%) patients. Following the third dose, anti-spike and anti-RBD levels peaked at 2 months, with geometric mean levels at 1131 and 1672 binding antibody units per milliliter (BAU/mL), respectively, and seropositivity rates above 93% and 85%, respectively, over the 9-month follow-up period. There was no association between eGFR or urine albumin-creatinine ratio (ACR) with mounting a robust antibody response or in antibody levels over time. The NDD-CKD patients on immunosuppressive treatment were less likely to mount a robust anti-spike response in univariable (odds ratio [OR] 0.43, 95% confidence interval [CI]: 0.20, 0.93) and multivariable (OR 0.52, 95% CI: 0.25, 1.10) analyses. An interaction between age, immunoglobulin G (IgG) antibody levels, and time was observed in both unadjusted (anti-spike: P = .005; anti-RBD: P = .03) and adjusted (anti-spike: P = .004; anti-RBD: P = .03) models, with older individuals having a more pronounced decline in antibody levels over time.

Conclusion

Most NDD-CKD patients were seropositive for anti-spike and anti-RBD after 3 doses of mRNA COVID-19 vaccines and we did not observe any differences in the antibody response by eGFR.

Alignment Among Patient, Caregiver, and Health Care Provider Perspectives on Hemodialysis Vascular Access Decision-Making: A Qualitative Study

Background

Updates to the Kidney Disease Outcomes Quality Initiative Clinical Practice Guideline for Vascular Access emphasize the "right access, in the right patient, at the right time, for the right reasons." Although this implies a collaborative approach, little is known about how patients, their caregivers, and health care providers engage in vascular access (VA) decision-making.

Objective

To explore how the perspectives of patients receiving hemodialysis, their caregivers, and hemodialysis care team align and diverge in relation to VA selection.

Design

Qualitative descriptive study.

Setting

Five outpatient hemodialysis centers in Calgary, Alberta.

Participants

Our purposive sample included 19 patients receiving maintenance hemodialysis, 2 caregivers, and 21 health care providers (7 hemodialysis nurses, 6 VA nurses, and 8 nephrologists).

Methods

We conducted semi-structured interviews with consenting participants. Using an inductive thematic analysis approach, we coded transcripts in duplicate and characterized themes addressing our research objective.

Results

While participants across roles shared some perspectives related to VA decision-making, we identified areas where views diverged. Areas of alignment included (1) optimizing patient preparedness-acknowledging decisional readiness and timing, and (2) value placed on trusting relationships with the kidney care team-respecting decisional autonomy with guidance. Perspectives diverged in the following aspects: (1) differing VA priorities and preferences-patients' emphasis on minimizing disruptions to normalcy contrasted with providers' preferences for fistulas and optimizing biomedical parameters of dialysis; (2) influence of personal and peer experience-patients preferred pragmatic, experiential knowledge, whereas providers emphasized informational credibility; and (3) endpoints for VA review-reassessment of VA decisions was prompted by access dissatisfaction for patients and a medical imperative to achieve a functioning access for health care providers.

Limitations

Participation was limited to individuals comfortable communicating in English and from urban, in-center hemodialysis units. Few informal caregivers of people receiving hemodialysis and younger patients participated in this study.

Conclusions

Although patients, caregivers, and healthcare providers share perspectives on important aspects of VA decisions, conflicting priorities and preferences may impact the decisional outcome. Findings highlight opportunities to bridge knowledge and readiness gaps and integrate shared decision-making in the VA selection process.

BNT162b2 versus mRNA-1273 Third Dose COVID-19 Vaccine in Patients with CKD and Maintenance Dialysis Patients

BACKGROUND

There is a lack of randomized controlled trial data regarding differences in immunogenicity of varying coronavirus disease 2019 (COVID-19) mRNA vaccine regimens in CKD populations.

METHODS

We conducted a randomized controlled trial at three kidney centers in Toronto, Ontario, Canada, evaluating the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) antibody response after third dose vaccination. Participants ( n =273) with CKD not on dialysis or receiving dialysis were randomized 1:1 to third dose 30- µ g BNT162b2 (Pfizer-BioNTech) or 100- µ g mRNA-1273 (Moderna). The primary outcome of this study was SARS-CoV-2 IgG-binding antibodies to the receptor-binding domain (anti-RBD). Spike protein (antispike), nucleocapsid protein, and vaccine reactogenicity were also evaluated. Serology was measured before third dose and 1, 3, and 6 months after third dose. A subset of participants ( n =100) were randomly selected to assess viral pseudovirus neutralization against wild-type D614G, B.1.617.2 (Delta), and B.1.1.529 (Omicron BA.1).

RESULTS

Among 273 participants randomized, 94% were receiving maintenance dialysis and 59% received BNT162b2 for initial two dose COVID-19 vaccination. Third dose of mRNA-1273 was associated with higher mean anti-RBD levels (1871 binding antibody units [BAU]/ml; 95% confidence interval [CI], 829 to 2988) over a 6-month period in comparison with third dose BNT162b2 (1332 BAU/ml; 95% CI, 367 to 2402) with a difference of 539 BAU/ml (95% CI, 139 to 910; P = 0.009). Neither antispike levels nor neutralizing antibodies to wild-type, Delta, and Omicron BA.1 pseudoviruses were statistically different. COVID-19 infection occurred in 10% of participants: 15 (11%) receiving mRNA-1273 and 11 (8%) receiving BNT162b2. Third dose BNT162b2 was not associated with a significant different risk for COVID-19 in comparison with mRNA-1273 (hazard ratio, 0.78; 95% CI, 0.27 to 2.2; P = 0.63).

CONCLUSIONS

In patients with CKD, third dose COVID-19 mRNA vaccination with mRNA-1273 elicited higher SARS-CoV-2 anti-RBD levels in comparison with BNT162b2 over a 6-month period.

CLINICAL TRIAL REGISTRY NAME AND REGISTRATION NUMBER

COVID-19 Vaccine Boosters in Patients With CKD (BOOST KIDNEY), NCT05022329 .

Short Timeframe Prediction of Kidney Failure among Patients with Advanced Chronic Kidney Disease

BACKGROUND

Development of a short timeframe (6-12 months) kidney failure risk prediction model may serve to improve transitions from advanced chronic kidney disease (CKD) to kidney failure and reduce rates of unplanned dialysis. The optimal model for short timeframe kidney failure risk prediction remains unknown.

METHODS

This retrospective study included 1757 consecutive patients with advanced CKD (mean age 66 years, estimated glomerular filtration rate 18 mL/min/1.73 m2). We compared the performance of Cox regression models using (a) baseline variables alone, (b) time-varying variables and machine learning models, (c) random survival forest, (d) random forest classifier in the prediction of kidney failure over 6/12/24 months. Performance metrics included area under the receiver operating characteristic curve (AUC-ROC) and maximum precision at 70% recall (PrRe70). Top-performing models were applied to 2 independent external cohorts.

RESULTS

Compared to the baseline Cox model, the machine learning and time-varying Cox models demonstrated higher 6-month performance [Cox baseline: AUC-ROC 0.85 (95% CI 0.84-0.86), PrRe70 0.53 (95% CI 0.51-0.55); Cox time-varying: AUC-ROC 0.88 (95% CI 0.87-0.89), PrRe70 0.62 (95% CI 0.60-0.64); random survival forest: AUC-ROC 0.87 (95% CI 0.86-0.88), PrRe70 0.61 (95% CI 0.57-0.64); random forest classifier AUC-ROC 0.88 (95% CI 0.87-0.89), PrRe70 0.62 (95% CI 0.59-0.65)]. These trends persisted, but were less pronounced, at 12 months. The random forest classifier was the highest performing model at 6 and 12 months. At 24 months, all models performed similarly. Model performance did not significantly degrade upon external validation.

CONCLUSIONS

When predicting kidney failure over short timeframes among patients with advanced CKD, machine learning incorporating time-updated data provides enhanced performance compared with traditional Cox models.

Omicron variant neutralizing antibodies following BNT162b2 BA.4/5 versus mRNA-1273 BA.1 bivalent vaccination in patients with end-stage kidney disease

Neutralization of Omicron subvariants by different bivalent vaccines has not been well evaluated. This study characterizes neutralization against Omicron subvariants in 98 individuals on dialysis or with a kidney transplant receiving the BNT162b2 (BA.4/BA.5) or mRNA-1273 (BA.1) bivalent COVID-19 vaccine. Neutralization against Omicron BA.1, BA.5, BQ.1.1, and XBB.1.5 increased by 8-fold one month following bivalent vaccination. In comparison to wild-type (D614G), neutralizing antibodies against Omicron-specific variants were 7.3-fold lower against BA.1, 8.3-fold lower against BA.5, 45.8-fold lower against BQ.1.1, and 48.2-fold lower against XBB.1.5. Viral neutralization was not significantly different by bivalent vaccine type for wild-type (D614G) (P = 0.48), BA.1 (P = 0.21), BA.5 (P = 0.07), BQ.1.1 (P = 0.10), nor XBB.1.5 (P = 0.10). Hybrid immunity conferred higher neutralizing antibodies against all Omicron subvariants. This study provides evidence that BNT162b2 (BA.4/BA.5) and mRNA-1273 (BA.1) induce similar neutralization against Omicron subvariants, even when antigenically divergent from the circulating variant.

Social determinants of health and the transition from advanced chronic kidney disease to kidney failure

BACKGROUND

The transition from chronic kidney disease (CKD) to kidney failure is a vulnerable time for patients, with suboptimal transitions associated with increased morbidity and mortality. Whether social determinants of health are associated with suboptimal transitions is not well understood.

METHODS

This retrospective cohort study included 1070 patients with advanced CKD who were referred to the Ottawa Hospital Multi-Care Kidney Clinic and developed kidney failure (dialysis or kidney transplantation) between 2010 and 2021. Social determinant information, including education level, employment status and marital status, was collected under routine clinic protocol. Outcomes surrounding suboptimal transition included inpatient (versus outpatient) dialysis starts, pre-emptive (versus delayed) access creation and pre-emptive kidney transplantation. We examined the association between social determinants of health and suboptimal transition outcomes using multivariable logistic regression.

RESULTS

The mean age and estimated glomerular filtration rate were 63 years and 18 ml/min/1.73 m2, respectively. Not having a high school degree was associated with higher odds for an inpatient dialysis start compared with having a college degree {odds ratio [OR] 1.71 [95% confidence interval (CI) 1.09-2.69]}. Unemployment was associated with higher odds for an inpatient dialysis start [OR 1.85 (95% CI 1.18-2.92)], lower odds for pre-emptive access creation [OR 0.53 (95% CI 0.34-0.82)] and lower odds for pre-emptive kidney transplantation [OR 0.48 (95% CI 0.24-0.96)] compared with active employment. Being single was associated with higher odds for an inpatient dialysis start [OR 1.44 (95% CI 1.07-1.93)] and lower odds for pre-emptive access creation [OR 0.67 (95% CI 0.50-0.89)] compared with being married.

CONCLUSIONS

Social determinants of health, including education, employment and marital status, are associated with suboptimal transitions from CKD to kidney failure.

COVID-19 Vaccine Effectiveness Among Patients With Maintenance Dialysis; Observations From Population Level Cohort Studies in 2 Large Canadian Provinces

Background

It was unknown if the effectiveness of COVID-19 vaccines could vary between regions.

Objective

To explore key differences in COVID-19 pandemics in British Columbia (BC) and Ontario (ON) and to investigate if the vaccine effectiveness (VE) among maintenance dialysis population could vary between these 2 provinces.

Study Design

Retrospective cohort.

Setting and Patients

This retrospective cohort study included patients from population-level registry in BC who were on maintenance dialysis from December 14, 2020, to December 31, 2021. The COVID-19 VE among BC patients were compared to the previously published VE among similar patient population in ON. Two-sample t-test for unpaired data were used to investigate if the VE estimates from BC and ON were statistically significantly different.

Exposure

Exposure to COVID-19 vaccines (BNT162b2, ChAdOx1nCoV-19, mRNA-1273) was modeled in a time-dependent fashion.

Outcome

Reverse transcription polymerase chain reaction (RT-PCR) confirmed COVID-19 infection and related severe outcome defined by hospitalization or death.

Analytical Approach

Time-dependent Cox regression analysis.

Results

This study using BC data included 4284 patients. Median age was 70 years and 61% was male. Median follow-up time was 382 days. 164 patients developed COVID-19 infection. The ON study by Oliver et al included 13 759 patients with a mean age of 68 years. 61% of the study sample was male. Median follow-up time for patients in the ON study was 102 days. A total of 663 patients developed COVID-19 infection. During the overlapped study periods, BC had 1 pandemic wave compared to 2 in Ontario with substantially higher infection rates. Vaccination timing and roll out among the study population were substantially different. Median time between first and second dose was 77 days (interquartile range [IQR] 66-91) in BC compared to 39 days (IQR = 28-56) in Ontario. Distribution of COVID-19 variants during the study period appeared to be similar. In BC, compared to pre-vaccination person-time, risk of developing COVID-19 infection was 64% (aHR [95% CI] 0.36 [0.21, 0.63]), 80% (0.20 [0.12, 0.35]) and 87% (0.13 [0.06, 0.29]) less when exposed to 1 dose, 2 doses, and 3 doses, respectively. In contrast, risk reduction among Ontario patients was 41% (0.59 [0.46, 0.76]) and 69% (0.31 [0.22, 0.42]) for 1 dose and 2 doses, respectively (patients did not receive the third dose by study end date of June 30, 2021). VE against COVID-19 infection in BC and ON was not statistically significantly different, the P values for exposure to 1 dose and 2 doses comparisons were 0.103 and 0.163, respectively. Similarly, in BC, risk of developing COVID-19-related hospitalization or death were 54% (0.46 [0.24, 0.90]), 75% (0.25 [0.13, 0.48]) and 86% (0.14 [0.06, 0.34]) less for 1 dose, 2 doses, and 3 doses, respectively. Interestingly, exposure to second dose appeared to provide better protection against severe outcomes in Ontario versus BC, risk reduction was 83% (aHR = 0.17, 95% CI [0.10, 0.30]) and 75% (aHR = 0.25, 95% CI [0.13, 0.48]), respectively. However, the adjusted hazard ratios were not statistically significantly different between BC and ON, the P values were 0.676 and 0.369 for exposure to 1 dose and 2 doses, respectively.

Limitations

Infection rate, variant distribution, and vaccination strategies were compared using publicly available data. VE estimates were compared from 2 independent cohort studies from 2 provinces without patient-level data sharing.

Conclusions

Health Canada approved COVID-19 vaccines were highly effective among patients with maintenance dialysis from BC and ON. Although there appeared to be between province differences in pandemic waves and vaccination strategies, the VE against COVID-19 infection as well as related severe outcome appeared to be not statistically significantly different. A nationally representative VE could be estimated using pooled data from multiple regions.

Clinical Outcomes and Vaccine Effectiveness for SARS-CoV-2 Infection in People Attending Advanced CKD Clinics: A Retrospective Provincial Cohort Study

BACKGROUND

People with advanced CKD are at high risk of mortality and morbidity from coronavirus disease 2019 (COVID-19). We measured rates of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection and severe outcomes in a large population attending advanced CKD clinics during the first 21 months of the pandemic. We examined risk factors for infection and case fatality, and we assessed vaccine effectiveness in this population.

METHODS

In this retrospective cohort study, we analyzed data on demographics, diagnosed SARS-CoV-2 infection rates, outcomes, and associated risk factors, including vaccine effectiveness, for people attending a province-wide network of advanced CKD clinics during the first four waves of the pandemic in Ontario, Canada.

RESULTS

In a population of 20,235 patients with advanced CKD, 607 were diagnosed with SARS-CoV-2 infection over 21 months. The case fatality rate at 30 days was 19% overall but declined from 29% in the first wave to 14% in the fourth. Hospitalization and intensive care unit (ICU) admission rates were 41% and 12%, respectively, and 4% started long-term dialysis within 90 days. Significant risk factors for diagnosed infection on multivariable analysis included lower eGFR, higher Charlson Comorbidity Index, attending advanced CKD clinics for more than 2 years, non-White ethnicity, lower income, living in the Greater Toronto Area, and long-term care home residency. Being doubly vaccinated was associated with lower 30-day case fatality rate (odds ratio [OR], 0.11; 95% confidence interval [CI], 0.03 to 0.52). Older age (OR, 1.06 per year; 95% CI, 1.04 to 1.08) and higher Charlson Comorbidity Index (OR, 1.11 per unit; 95% CI, 1.01 to 1.23) were associated with higher 30-day case fatality rate.

CONCLUSIONS

People attending advanced CKD clinics and diagnosed with SARS-CoV-2 infection in the first 21 months of the pandemic had high case fatality and hospitalization rates. Fatality rates were significantly lower in those who were doubly vaccinated.

PODCAST

This article contains a podcast at https://dts.podtrac.com/redirect.mp3/www.asn-online.org/media/podcast/CJASN/2023_04_10_CJN10560922.mp3.

Effectiveness of Three Doses of mRNA COVID-19 Vaccines in the Hemodialysis Population during the Omicron Period

BACKGROUND

Coronavirus disease 2019 (COVID-19) vaccine effectiveness studies in the hemodialysis population have demonstrated that two doses of mRNA COVID-19 vaccines are effective against severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection and severe complications when Alpha and Delta were predominant variants of concern. Vaccine effectiveness after a third dose versus two doses for preventing SARS-CoV-2 infection and severe COVID-19 in the hemodialysis population against Omicron is not known.

METHODS

We conducted a retrospective cohort study in Ontario, Canada, between December 1, 2021, and February 28, 2022, in the maintenance hemodialysis population who had received two versus three doses of mRNA COVID-19 vaccines. COVID-19 vaccination, SARS-CoV-2 infection, and related hospitalization and death were determined from provincial databases. The primary outcome was the first RT-PCR confirmed SARS-CoV-2 infection, and the secondary outcome was a SARS-CoV-2-related severe outcome, defined as either hospitalization or death.

RESULTS

A total of 8457 individuals receiving in-center hemodialysis were included. At study initiation, 2334 (28%) individuals received three doses, which increased to 7468 (88%) individuals by the end of the study period. The adjusted hazard ratios (aHR) for SARS-CoV-2 infection (aHR, 0.58; 95% confidence interval [CI], 0.50 to 0.67) and severe outcomes (hospitalization or death) (aHR, 0.40; 95% CI, 0.28 to 0.56) were lower after three versus two doses of mRNA vaccine. Prior infection, independent of vaccine status, was associated with a lower risk of reinfection, with an aHR of 0.44 (95% CI, 0.27 to 0.73).

CONCLUSIONS

Three-dose mRNA COVID-19 vaccination was associated with lower incidence of SARS-CoV-2 infection and severe SARS-CoV-2-related outcomes during the Omicron period compared with two doses.

Magnesium and Fracture Risk in the General Population and Patients Receiving Dialysis: A Narrative Review

Purpose of Review

Magnesium is an essential mineral for bone metabolism, but little is known about how magnesium intake alters fracture risk. We conducted a narrative review to better understand how magnesium intake, through supplementation, diet, or altering the concentration of dialysate magnesium, affects mineral bone disease and the risk of fracture in individuals across the spectrum of kidney disease.

Sources of Information

Peer-reviewed clinical trials and observational studies.

Methods

We searched for relevant articles in MEDLINE and EMBASE databases. The methodologic quality of clinical trials was assessed using a modified version of the Downs and Black criteria checklist.

Key Findings

The role of magnesium intake in fracture prevention is unclear in both the general population and in patients receiving maintenance dialysis. In those with normal kidney function, 2 meta-analyses showed higher bone mineral density in those with higher dietary magnesium, whereas 1 systematic review showed no effect on fracture risk. In patients receiving maintenance hemodialysis or peritoneal dialysis, a higher concentration of dialysate magnesium is associated with a lower concentration of parathyroid hormone, but little is known about other bone-related outcomes. In 2 observational studies of patients receiving hemodialysis, a higher concentration of serum magnesium was associated with a lower risk of hip fracture.

Limitations

This narrative review included only articles written in English. Observed effects of magnesium intake in the general population may not be applicable to those with chronic kidney disease particularly in those receiving dialysis.

Infection Control Practices in In-Center Hemodialysis Units During Wave 1 of the COVID-19 Pandemic in Ontario, Canada: Research Letter

Background

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is a virus that caused coronavirus disease 2019 (COVID-19), the multisystem disease central to the COVID-19 pandemic. As patients receiving in-center maintenance hemodialysis require treatment 3 times weekly, they were unable to fully isolate. It was important for in-center hemodialysis units to implement robust infection control practices to ensure patient safety and minimize risk of transmitting SARS-CoV-2 among patients and staff. There are 27 renal programs within Ontario, Canada, providing care for about 9000 people across about 100 in-center hemodialysis units. These units are funded by the Ontario Renal Network (ORN), which is part of the provincial agency Ontario Health.

Objective

The objective was to track infection control practices that were implemented by in-center hemodialysis units and be able to provide a descriptive narrative of the COVID-19 pandemic response of Ontario's hemodialysis units between March and September 2020.

Methods

Between May and September 2020, data were collected from Ontario's 27 renal programs on the implementation of key infection control practices, including symptom screening, use of personal protective equipment, testing, practices specifically related to patients from congregate living settings, other prevention practices, and outbreak management. There were 4 data collection cycles, each approximately 1 month apart. The results were compiled and shared across the province, and infection control practices were also discussed at provincial COVID-19 teleconferences hosted by the ORN.

Results

By March 2020, all but one renal program had implemented one or more forms of symptom screening, all renal programs had implemented physical distancing in waiting rooms and restricted visitors, and 74% of renal programs had implemented universal masking for all staff. By April 2020, 89% of renal programs had implemented universal masking for all patients, 52% had implemented enhanced contact and droplet precautions for suspected or positive cases, and 59% of renal programs tested all patients from congregate living settings regularly (with a low symptom threshold for testing). Infection control practices became more homogeneous across renal programs over time, and most practices were in place as of the last data collection.

Conclusions

The renal system in Ontario was able to respond quickly within the first 2 months of the pandemic to minimize the spread of COVID-19 within in-center hemodialysis units. Through provincial teleconferences, infection control practices were shared across the province as the pandemic and hemodialysis unit responses evolved. This supported renal programs to advocate locally if their hospital was lagging in practices felt to be of value in other hemodialysis units. Although no direct correlation can be made regarding the implementation of infection control practices within in-center hemodialysis units and the number of COVID-19 cases in this population, the limited number of outbreaks in hemodialysis units may have been influenced by the proactive response of renal programs. Practices described in this article may support management and response to subsequent waves of COVID-19 or future similar infectious diseases.

Determining the Longitudinal Serologic Response to COVID-19 Vaccination in the Chronic Kidney Disease Population: A Clinical Research Protocol

Background

People living with chronic kidney disease (CKD) have been disproportionately affected by the coronavirus disease 2019 (COVID-19) pandemic, including higher rates of infection, hospitalization, and death. Data on responsiveness to COVID-19 vaccination strategies and immunogenicity are limited, yet required to inform vaccination strategies in this at-risk population.

Objective

The objective of this study is to characterize the longitudinal serologic response to COVID-19 vaccination.

Design

This is a prospective observational cohort study.

Setting

Participating outpatient kidney programs within Ontario and British Columbia.

Patients

Up to 2500 participants with CKD G3b-5D receiving COVID-19 vaccination, including participants receiving dialysis and kidney transplant recipients (CKD G1T-5T).

Measurements

The severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) IgG antibodies (anti-spike, anti-receptor binding domain, anti-nucleocapsid) will be detected by ELISA (enzyme-linked immunosorbent assay) from serum or dried blood spot testing. In a subset of participants, neutralizing antibodies against novel variants of concern will be evaluated. Peripheral blood mononuclear cells will be collected for exploratory immune profiling of SARS-CoV-2 specific cellular immunity.

Methods

Participants will be recruited prior to or following any COVID-19 vaccine dose and have blood sampled for serological testing at multiple timepoints: 1, 3, 6, 9, and 12 months post vaccination. When possible, samples will be collected prior to a dose or booster. Participants will remain in the study for at least 1 year following their last COVID-19 vaccine dose.

Strengths and limitations

The adaptive design of this study allows for planned modification based on emerging evidence or rapid changes in public health policy surrounding vaccination. Limitations include incomplete earlier timepoints for blood collection due to rapid vaccination of the population.

Conclusions

This large multicenter serologic study of participants living with kidney disease will generate data on the kinetics of SARS-CoV-2 immune response to vaccination across the spectrum of CKD, providing insights into the amplitude and duration of immunity conferred by COVID-19 vaccination and allowing for characterization of factors associated with immune response. The results of this study may be used to inform immunization guidelines and public health recommendations for the 4 million Canadians living with CKD.

Patient and Clinician Perspectives on Shared Decision Making in Vascular Access Selection: A Qualitative Study

RATIONALE & OBJECTIVE

Collaborative approaches to vascular access selection are being increasingly encouraged to elicit patients' preferences and priorities where no unequivocally superior choice exists. We explored how patients, their caregivers, and clinicians integrate principles of shared decision making when engaging in vascular access discussions.

STUDY DESIGN

Qualitative description.

SETTING & PARTICIPANTS

Semistructured interviews with a purposive sample of patients, their caregivers, and clinicians from outpatient hemodialysis programs in Alberta, Canada.

ANALYTICAL APPROACH

We used a thematic analysis approach to inductively code transcripts and generate themes to capture key concepts related to vascular access shared decision making across participant roles.

RESULTS

42 individuals (19 patients, 2 caregivers, 21 clinicians) participated in this study. Participants identified how access-related decisions follow a series of major decisions about kidney replacement therapy and care goals that influence vascular access preferences and choice. Vascular access shared decision making was strengthened through integration of vascular access selection with dialysis-related decisions and timely, tailored, and balanced exchange of information between patients and their care team. Participants described how opportunities to revisit the vascular access decision before and after dialysis initiation helped prepare patients for their access and encouraged ongoing alignment between patients' care priorities and treatment plans. Where shared decision making was undermined, hemodialysis via a catheter ensued as the most readily available vascular access option.

LIMITATIONS

Our study was limited to patients and clinicians from hemodialysis care settings and included few caregiver participants.

CONCLUSIONS

Findings suggest that earlier, or upstream, decisions about kidney replacement therapies influence how and when vascular access decisions are made. Repeated vascular access discussions that are integrated with other higher-level decisions are needed to promote vascular access shared decision making and preparedness.

Using pseudo-absence models to test for environmental selection in marine movement ecology: the importance of sample size and selection strength

BACKGROUND

Understanding the selection of environmental conditions by animals requires knowledge of where they are, but also of where they could have been. Presence data can be accurately estimated by direct sampling, sightings, or through electronic tag deployments. However, absence data are harder to determine because absences are challenging to measure in an uncontrolled setting. To address this problem, ecologists have developed different methods for generating pseudo-absence data relying on theoretical movement models. These null models represent the movement of environmentally naive individuals, creating a set of locations that animals could have been if they were not exhibiting environmental selection.

METHODS

Here, we use four different kinds of null animal movement models-Brownian motion, Lévy walks, Correlated random walks, and Joint correlated random walks to test the ability and power of each of these null movement models to serve as appropriate animal absence models. We use Kolmogorov-Smirnov tests to detect environmental selection using two data sets, one of simulated animal tracks biased towards warmer sea surface temperatures, and one of 57 observed blue shark tracks of unknown sea surface temperature selection.

RESULTS

The four different types of movement models showed minimal difference in the ability to serve as appropriate null models for environmental selection studies. Selection strength and sample size were more important in detecting true environmental selection. We show that this method can suffer from high false positive rates, especially in the case where animals are not selecting for specific environments. We provide estimates of test accuracy at different sample sizes and selection strengths to avoid false positives when using this method.

CONCLUSION

We show how movement models can be used to generate pseudo-absences and test for habitat selection in marine organisms. While this approach efficiently detects environmental selection in marine organisms, it cannot detect the underlying mechanisms driving this selection.

The availability of support and peritoneal dialysis survival: A cohort study

BACKGROUND

Providing support is important to maintain a patient on peritoneal dialysis (PD), though its impact on outcomes has not been investigated thoroughly. We examined the association between having support and risk of a transfer to hemodialysis.

METHODS

In this retrospective observational cohort study, we used data captured in the Dialysis Measurement Analysis and Reporting system about patients who started PD in Alberta, Canada, between 1 January 2013 and 30 September 2018. Support was defined as the availability of a support person in the home who was able, willing and available to provide support for PD in the patient's residence. The outcome of interest was a transfer to hemodialysis for at least 90 days. We estimated the cumulative incidence of a transfer over time accounting for competing risks and hazard ratios to summarise the association between support and a transfer. We split follow-up time as hazard ratios varied over time.

RESULTS

Six hundred and eighty-three incident PD patients, median age 58 years (IQR: 47-68) and 35% female, were followed for a median of 15 months. The cumulative incidence of a transfer to hemodialysis at 24 months was 26%. Having support was associated with a reduced risk of a transfer between 3 and 12 months after the start of dialysis (HR_3-12mo: 0.44; 95% CI: 0.25-0.78), but not earlier (hazard ratio (HR)_<3mo: 0.96; 95% confidence interval (CI): 0.55-1.69) or later (HR_>12mo: 1.19; 95% CI: 0.65-2.17).

CONCLUSIONS

A transfer to hemodialysis is common. Having a support person at home is associated with a short-term protective effect after the initiation of PD.

Vaccine Effectiveness Against SARS-CoV-2 Infection and Severe Outcomes in the Maintenance Dialysis Population in Ontario, Canada

BACKGROUND

Vaccination studies in the hemodialysis population have demonstrated decreased antibody response compared with healthy controls, but vaccine effectiveness for preventing SARS-CoV-2 infection and severe disease is undetermined.

METHODS

We conducted a retrospective cohort study in the province of Ontario, Canada, between December 21, 2020, and June 30, 2021. Receipt of vaccine, SARS-CoV-2 infection, and related severe outcomes (hospitalization or death) were determined from provincial health administrative data. Receipt of one and two doses of vaccine were modeled in a time-varying cause-specific Cox proportional hazards model, adjusting for baseline characteristics, background community infection rates, and censoring for non-COVID death, recovered kidney function, transfer out of province, solid organ transplant, and withdrawal from dialysis.

RESULTS

Among 13,759 individuals receiving maintenance dialysis, 2403 (17%) were unvaccinated and 11,356 (83%) had received at least one dose by June 30, 2021. Vaccine types were BNT162b2 (n=8455, 74%) and mRNA-1273 (n=2901, 26%); median time between the first and second dose was 36 days (IQR 28-51). The adjusted hazard ratio (HR) for SARS-CoV-2 infection and severe outcomes for one dose compared with unvaccinated was 0.59 (95% CI, 0.46 to 0.76) and 0.54 (95% CI, 0.37 to 0.77), respectively, and for two doses compared with unvaccinated was 0.31 (95% CI, 0.22 to 0.42) and 0.17 (95% CI, 0.1 to 0.3), respectively. There were no significant differences in vaccine effectiveness among age groups, dialysis modality, or vaccine type.

CONCLUSIONS

COVID-19 vaccination is effective in the dialysis population to prevent SARS-CoV-2 infection and severe outcomes, despite concerns about suboptimal antibody responses.

Differences in mRNA-1273 (Moderna) and BNT162b2 (Pfizer-BioNTech) SARS-CoV-2 vaccine immunogenicity among patients undergoing dialysis

BACKGROUND

Differences in immunogenicity between mRNA SARS-CoV-2 vaccines have not been well characterized in patients undergoing dialysis. We compared the serologic response in patients undergoing maintenance hemodialysis after vaccination against SARS-CoV-2 with BNT162b2 (Pfizer-BioNTech) and mRNA-1273 (Moderna).

METHODS

We conducted a prospective observational cohort study at 2 academic centres in Toronto, Canada, from Feb. 2, 2021, to July 20, 2021, which included 129 and 95 patients who received the BNT162b2 and mRNA-1273 SARS-CoV-2 vaccines, respectively. We measured SARS-CoV-2 immunoglobulin G antibodies to the spike protein (anti-spike), receptor binding domain (anti-RBD) and nucleocapsid protein (anti-NP) at 6-7 and 12 weeks after the second dose of vaccine and compared those levels with the median convalescent serum antibody levels from 211 controls who were previously infected with SARS-CoV-2.

RESULTS

At 6-7 weeks after 2-dose vaccination, we found that 51 of 70 patients (73%) who received BNT162b2 and 83 of 87 (95%) who received mRNA-1273 attained convalescent levels of anti-spike antibody (p < 0.001). In those who received BNT162b2, 35 of 70 (50%) reached the convalescent level for anti-RBD compared with 69 of 87 (79%) who received mRNA-1273 (p < 0.001). At 12 weeks after the second dose, anti-spike and anti-RBD levels were significantly lower in patients who received BNT162b2 than in those who received mRNA-1273. For anti-spike, 70 of 122 patients (57.4%) who received BNT162b2 maintained the convalescent level versus 68 of 71 (96%) of those who received mRNA-1273 (p < 0.001). For anti-RBD, 47 of 122 patients (38.5%) who received BNT162b2 maintained the anti-RBD convalescent level versus 45 of 71 (63%) of those who received mRNA-1273 (p = 0.002).

INTERPRETATION

In patients undergoing hemodialysis, mRNA-1273 elicited a stronger humoral response than BNT162b2. Given the rapid decline in immunogenicity at 12 weeks in patients who received BNT162b2, a third dose is recommended in patients undergoing dialysis as a primary series, similar to recommendations for other vulnerable populations.

Acute kidney injury requiring renal replacement therapy in people with COVID-19 disease in Ontario, Canada: a prospective analysis of risk factors and outcomes

Background

Severely ill people with coronavirus disease 2019 (COVID-19) are at risk of acute kidney injury treated with renal replacement therapy (AKI-RRT). The understanding of the risk factors and outcomes for AKI-RRT is incomplete.

Methods

We prospectively collected data on the incidence, demographics, area of residence, time course, outcomes and associated risk factors for all COVID-19 AKI-RRT cases during the first two waves of the pandemic in Ontario, Canada.

Results

There were 271 people with AKI-RRT, representing 0.1% of all diagnosed severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) cases. These included 10% of SARS-CoV-2 admissions to intensive care units (ICU). Median age was 65 years, with 11% &lt;50 years, 76% were male, 47% non-White and 48% had diabetes. Overall, 59% resided in the quintile of Ontario neighborhoods with the greatest ethnocultural composition and 51% in the two lowest income quintile neighborhoods. Mortality was 58% at 30 days after RRT initiation, and 64% at 90 days. By 90 days, 20% of survivors remained RRT-dependent and 31% were still hospitalized. On multivariable analysis, people aged &gt;70 years had higher mortality (odds ratio 2.4, 95% confidence interval 1.3, 4.6). Cases from the second versus the first COVID-19 wave were older, had more baseline comorbidity and were more likely to initiate RRT  &gt;2 weeks after SARS-CoV-2 diagnosis (34% versus 14%; P &lt; 0.001).

Conclusions

AKI-RRT is common in COVID-19 ICU admissions. Residency in areas with high ethnocultural composition and lower socioeconomic status are strong risk factors. Late-onset AKI-RRT was more common in the second wave. Mortality is high and 90-day survivors have persisting high morbidity.

Factors Affecting Cuff Extrusion of Tunneled Hemodialysis Catheters

PURPOSE

To identify patient and procedural factors associated with extrusion of the Dacron cuff from the subcutaneous tunnel of tunneled hemodialysis catheters (THDCs).

MATERIALS AND METHODS

Single center 5-year retrospective analysis of 625 catheters in 293 adult patients. Patient data included age, gender, body mass index (BMI), and common comorbidities. Procedural details included type of procedure (new insertion vs. exchange), operator seniority, side of insertion, catheter model and presence of catheter wings skin-sutures. Complications were reported as cumulative risk over time and Cox proportional hazards model was used to evaluate risk factors for cuff extrusion (CE).

RESULTS

Median patient follow-up was 503 days (188,913 catheter-days) and median catheter survival 163 days. CE occurred in 23.8% of catheters, at a rate of 0.79 per 1,000 catheter-days and a median time of 64 days. It was more common than infection (14.6%) and inadequate flow (15.5%). The 1-month and 12-month risk of CE was 5.9% and 21.3% respectively. A first episode of CE was a strong predictor of future CE episodes. The only patient factor that affected the risk of CE was BMI (Hazard Ratio 2.36 for obese patients). Procedural factors that affected the risk of CE, adjusted for BMI, were catheter model, type of procedure (lower risk for new insertions) and catheter wings skin-sutures; the latter reduced the 30-day CE risk by 76% without increasing catheter-related infections.

CONCLUSION

Cuff extrusion is common in long-term THDCs. The risk increases with obesity, history of previous cuff extrusion, certain catheter models and absence of wing-sutures.

MyTEMP: Statistical Analysis Plan of a Registry-Based, Cluster-Randomized Clinical Trial

Background:

Major Outcomes with Personalized Dialysate TEMPerature (MyTEMP) is a 4-year cluster-randomized clinical trial comparing the effect of using a personalized, temperature-reduced dialysate protocol versus a dialysate temperature of 36.5°C on cardiovascular-related death and hospitalization. Randomization was performed at the level of the dialysis center (“the cluster”).

Objective:

The objective is to outline the statistical analysis plan for the MyTEMP trial.

Design:

MyTEMP is a pragmatic, 2-arm, parallel-group, registry-based, open-label, cluster-randomized trial.

Setting:

A total of 84 dialysis centers in Ontario, Canada.

Patients:

Approximately 13 500 patients will have received in-center hemodialysis at the 84 participating dialysis centers during the trial period (April 3, 2017, to March 1, 2021, with a maximum follow-up to March 31, 2021).

Methods:

Patient identification, baseline characteristics, and study outcomes will be obtained primarily through Ontario administrative health care databases held at ICES. Covariate-constrained randomization was used to allocate the 84 dialysis centers (1:1) to the intervention group or the control group. Centers in the intervention group used a personalized, temperature-reduced dialysate protocol, and centers in the control group used a fixed dialysate temperature of 36.5°C.

Outcomes:

The primary outcome is a composite of cardiovascular-related death or major cardiovascular-related hospitalization (defined as a hospital admission with myocardial infarction, congestive heart failure, or ischemic stroke) recorded in administrative health care databases. The key secondary outcome is the mean drop in intradialytic systolic blood pressure, defined as the patients’ predialysis systolic blood pressure minus their nadir systolic blood pressure during the dialysis treatment. Anonymized data on patients’ predialysis and intradialytic systolic blood pressure were collected at monthly intervals from each dialysis center.

Analysis plan:

The primary analysis will follow an intent-to-treat approach. The primary outcome will be analyzed at the patient level as the hazard ratio of time-to-first event, estimated from a subdistribution hazards model. Within-center correlation will be accounted for using a robust sandwich estimator. In the primary analysis, patients’ observation time will end if they experience the primary outcome, emigrate from Ontario, or die of a noncardiovascular cause (which will be treated as a competing risk event). The between-group difference in the mean drop in intradialytic systolic blood pressure obtained during the dialysis sessions throughout the trial period will be analyzed at the center level using an unadjusted random-effects linear mixed model.

Trial status:

The MyTEMP trial period is April 3, 2017, to March 31, 2021. We expect to analyze and report results by 2023 once the updated data are available at ICES.

Trial registration:

MyTEMP is registered with the US National Institutes of Health at clincaltrials.gov (NCT02628366).

Statistical analytic plan:

Version 1.1 June 15, 2021.

Evaluation of the SARS-CoV-2 Antibody Response to the BNT162b2 Vaccine in Patients Undergoing Hemodialysis

IMPORTANCE

Patients undergoing hemodialysis have a high mortality rate associated with COVID-19, and this patient population often has a poor response to vaccinations. Randomized clinical trials for COVID-19 vaccines included few patients with kidney disease; therefore, vaccine immunogenicity is uncertain in this population.

OBJECTIVE

To evaluate the SARS-CoV-2 antibody response in patients undergoing chronic hemodialysis following 1 vs 2 doses of BNT162b2 COVID-19 vaccination compared with health care workers serving as controls and convalescent serum.

DESIGN, SETTING, AND PARTICIPANTS

A prospective, single-center cohort study was conducted between February 2 and April 17, 2021, in Toronto, Ontario, Canada. Participants included 142 patients receiving in-center hemodialysis and 35 health care worker controls.

EXPOSURES

BNT162b2 (Pfizer-BioNTech) COVID-19 vaccine.

MAIN OUTCOMES AND MEASURES

SARS-CoV-2 IgG antibodies to the spike protein (anti-spike), receptor binding domain (anti-RBD), and nucleocapsid protein (anti-NP).

RESULTS

Among the 142 participants undergoing maintenance hemodialysis, 94 (66%) were men; median age was 72 (interquartile range, 62-79) years. SARS-CoV-2 IgG antibodies were measured in 66 patients receiving 1 vaccine dose following a public health policy change, 76 patients receiving 2 vaccine doses, and 35 health care workers receiving 2 vaccine doses. Detectable anti-NP suggestive of natural SARS-CoV-2 infection was detected in 15 of 142 (11%) patients at baseline, and only 3 patients had prior COVID-19 confirmed by reverse transcriptase polymerase chain reaction testing. Two additional patients contracted COVID-19 after receiving 2 doses of vaccine. In 66 patients receiving a single BNT162b2 dose, seroconversion occurred in 53 (80%) for anti-spike and 36 (55%) for anti-RBD by 28 days postdose, but a robust response, defined by reaching the median levels of antibodies in convalescent serum from COVID-19 survivors, was noted in only 15 patients (23%) for anti-spike and 4 (6%) for anti-RBD in convalescent serum from COVID-19 survivors. In patients receiving 2 doses of BNT162b2 vaccine, seroconversion occurred in 69 of 72 (96%) for anti-spike and 63 of 72 (88%) for anti-RBD by 2 weeks following the second dose and median convalescent serum levels were reached in 52 of 72 patients (72%) for anti-spike and 43 of 72 (60%) for anti-RBD. In contrast, all 35 health care workers exceeded the median level of anti-spike and anti-RBD found in convalescent serum 2 to 4 weeks after the second dose.

CONCLUSIONS AND RELEVANCE

This study suggests poor immunogenicity 28 days following a single dose of BNT162b2 vaccine in the hemodialysis population, supporting adherence to recommended vaccination schedules and avoiding delay of the second dose in these at-risk individuals.

A satellite-based mobile warning system to reduce interactions with an endangered species

Earth-observing satellites are a major research tool for spatially explicit ecosystem nowcasting and forecasting. However, there are practical challenges when integrating satellite data into usable real-time products for stakeholders. The need of forecast immediacy and accuracy means that forecast systems must account for missing data and data latency while delivering a timely, accurate, and actionable product to stakeholders. This is especially true for species that have legal protection. Acipenser oxyrinchus oxyrinchus (Atlantic sturgeon) were listed under the United States Endangered Species Act in 2012, which triggered immediate management action to foster population recovery and increase conservation measures. Building upon an existing research occurrence model, we developed an Atlantic sturgeon forecast system in the Delaware Bay, USA. To overcome missing satellite data due to clouds and produce a 3-d forecast of ocean conditions, we implemented data interpolating empirical orthogonal functions (DINEOF) on daily observed satellite data. We applied the Atlantic sturgeon research model to the DINEOF output and found that it correctly predicted Atlantic sturgeon telemetry occurrences over 90% of the time within a 3-d forecast. A similar framework has been utilized to forecast harmful algal blooms, but to our knowledge, this is the first time a species distribution model has been applied to DINEOF gap-filled data to produce a forecast product for fishes. To implement this product into an applied management setting, we worked with state and federal organizations to develop real-time and forecasted risk maps in the Delaware River Estuary for both state-level managers and commercial fishers. An automated system creates and distributes these risk maps to subscribers' mobile devices, highlighting areas that should be avoided to reduce interactions. Additionally, an interactive web interface allows users to plot historic, current, future, and climatological risk maps as well as the underlying model output of Atlantic sturgeon occurrence. The mobile system and web tool provide both stakeholders and managers real-time access to estimated occurrences of Atlantic sturgeon, enabling conservation planning and informing fisher behavior to reduce interactions with this endangered species while minimizing impacts to fisheries and other projects.

Province-Wide Prevalence Testing for SARS-CoV-2 of In-Center Hemodialysis Patients and Staff in Ontario, Canada: A Cross-Sectional Study

Background:

People receiving in-center hemodialysis face a high risk for contracting severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) and experience poor outcomes. During the first wave of the coronavirus disease 2019 (COVID-19) pandemic in Ontario (between March and June 2020), it was unclear whether asymptomatic or presymptomatic cases were common and whether widespread testing of all dialysis patients and staff would identify cases earlier and prevent transmission. Ontario has a population of about 14.5 million. Approximately 8900 people receive dialysis across 102 in-center dialysis units.

Objective:

The objective of this study was to determine participation rates for patients and staff in point prevalence testing in dialysis units across the province and to determine the prevalence of asymptomatic or presymptomatic infection.

Design:

Cross-sectional study design.

Setting:

In-center hemodialysis units at 27 renal programs across Ontario.

Participants:

Patients and staff in in-center dialysis units in Ontario.

Measurements:

Participation rates, demographic data, SARS-CoV-2 positivity rates, and COVID-19-related symptom data.

Methods:

From June 8 to 30, 2020, all in-center dialysis patients and staff in the Province of Ontario were requested to undergo a symptom screening assessment and nasopharyngeal swab. Testing was done using polymerase chain reaction to detect SARS-CoV-2. A standardized questionnaire of atypical and typical COVID-19-related symptoms was administered to patients, to assess for new or worsening COVID-19-related symptoms.

Results:

Patient participation was 83% (7155 of 8612) of which 15 tests were positive: less than 5 (<0.07%) were new positive cases, 7 were false positive, and the remaining were recovered positives. Half of the new positive cases had symptoms. Common symptoms reported included fatigue (4%), falls (4%), runny nose (3%), dyspnea (3%), and cough (3%). Staff participation was 49% (2109 of 4325), and less than 5 (<0.24%) were asymptomatic positive.

Limitations:

As point prevalence testing was voluntary, not all patients and staff participated. Lower participation rate may be due to decreasing new cases in Ontario, and testing or pandemic fatigue, among other factors. This study did not use serology to identify prior infections because it was not widely available in Ontario. With respect to the standardized symptom questionnaire, it was only available in English and French and could not be tested due to the urgency of the initiative.

Conclusions:

Participation among patients in point prevalence testing was good, but participation among staff was relatively low. Asymptomatic positivity in the dialysis patient and staff population was rare during the first wave of the COVID-19 pandemic in Ontario.

COVID-19 chez les patients ontariens sous dialyse à long terme

CONTEXTE:

Les patients sous dialyse à long terme pourraient avoir un risque accru d’infection par le coronavirus du syndrome respiratoire aigu sévère 2 (SRAS-CoV-2), et de maladie et de mortalité associées. Nous avons voulu décrire l’incidence, les facteurs de risque et les issues de l’infection chez ces patients en Ontario (Canada).

MÉTHODES:

Nous avons utilisé des ensembles de données reliées pour comparer les caractéristiques de la maladie et la mortalité chez les patients sous dialyse à long terme en Ontario qui ont testé positif pour le SRAS-CoV-2 et ceux qui n’ont pas développé d’infection, entre le 12 mars et le 20 août 2020. Nous avons recueilli des données sur l’infection par le SRAS-CoV-2 de manière prospective. Nous avons évalué les facteurs de risque d’infection et de mortalité par des analyses de régression logistique multivariées.

RÉSULTATS:

Pendant la période à l’étude, 187 patients dialysés sur 12 501 (1,5 %) ont reçu un diagnostic d’infection par le SRAS-CoV-2. Parmi eux, 117 (62,6 %) ont été hospitalisés, et le taux de mortalité était de 28,3 %. Les facteurs prédictifs significatifs associés à l’infection incluaient l’hémodialyse dans un centre plutôt que la dialyse à domicile (rapport de cotes [RC] 2,54; intervalle de confiance [IC] à 95 % 1,59–4,05), le fait de vivre dans un établissement de soins de longue durée (RC 7,67; IC à 95 % 5,30–11,11), le fait d’habiter la région du Grand Toronto (RC 3,27; IC à 95 % 2,21–4,80), les ethnicités Noire (RC 3,05; IC à 95 % 1,95–4,77), du sous-continent indien (RC 1,70; IC à 95 % 1,02–2,81) et autres non blanches (RC 2,03; IC à 95 % 1,38–2,97) et les quintiles de revenu inférieurs (RC 1,82; IC à 95 % 1,15–2,89).

INTERPRÉTATION:

Les patients sous dialyse à long terme sont exposés à un risque accru d’infection par le SRAS-CoV-2 et de mortalité due à la maladie à coronavirus 2019. Il faudra travailler à éliminer les facteurs de risque d’infection et vacciner ces patients en priorité.

Starting Dialysis on Time, At Home on the Right Therapy (START): Description of an Intervention to Increase the Safe and Effective Use of Peritoneal Dialysis

Background:

Most of the patients with end-stage kidney failure are treated with dialysis. Jurisdictions around the world are actively promoting peritoneal dialysis (PD) because it is equivalent to hemodialysis in terms of clinical outcomes, but is less costly. Unfortunately, PD penetration remains low.

Objectives:

The Starting dialysis on Time, At Home, on the Right Therapy (START) Project had 2 overarching goals: (1) to provide information that would help programs increase the safe and effective use of PD, and (2) to reduce inappropriate, early initiation of dialysis in patients with kidney failure. In this article, we focus on the first objective and describe the rationale for START and the methods employed.

Design:

The START Project was a comprehensive, province-wide quality improvement intervention.

Setting:

The START project was implemented in both Alberta Kidney Care (AKC)-South and AKC-North, including all 7 renal programs in the province.

Patients:

The project included all patients who commenced maintenance dialysis between October 1, 2015, and March 31, 2018, in Alberta, Canada who met our inclusion criteria.

Measurements:

We reported baseline characteristics of incident dialysis patients overall, and by site. Our key performance indicator was the proportion of patients who received PD for any period of time within 180 days of the first dialysis treatment. Reports also included detailed metrics pertaining to the 6 steps in the process of modality selection and we had the capacity to provide more granular data on an as-needed basis. To understand loss of PD patients, we reported the numbers of incident patients who recovered kidney function, experienced technique failure, received a transplant, were lost to follow-up, transferred to another program, or died.

Methods:

START provided dialysis programs with a conceptual framework for understanding the drivers of PD utilization. High-quality, detailed data were collected using a tool that was custom-built for this purpose, and were mapped to steps in the process of care that drove the outcomes of interest. This allowed sites to identify gaps in care, develop action plans, and implement local interventions to address them. The process was supported by an Innovation Learning Collaborative consisting of 3 learning sessions that brought frontline staff together from across the province to share strategies and learnings. Ongoing data collection allowed teams to determine whether their interventions were effective at each subsequent learning session, and to revisit their interventions if required (the “Plan-Do-Study-Act Cycle”).

Results:

Future work will report on the impact of the START project on incident PD utilization at a provincial and regional level.

Limitations:

The time required to design and implement interventions in practice, as well as the need for multiple PDSA (Plan-Do-Study-Act) cycles to see results, meant that the true potential may not be realized during a relatively short intervention period. Change required buy-in and support from local and provincial leadership and frontline staff. In the absence of accountability for local performance, we relied on the goodwill of participating programs to use the information and resources provided to effect change. Finally, the burden of documentation and data collection for frontline staff was high at baseline. We anticipated that adding supplemental data collection would be difficult.

Conclusions:

The START project was a comprehensive, province-wide initiative to maximize the safe and effective use of PD in Alberta, Canada. It standardized the management of incident dialysis patients, leveraged high-quality data to facilitate the reporting of metrics mapped to steps in the process of care that drove incident PD utilization, and helped programs to identify gaps in care and target them for improvement. Future work will report on the impact of the program on incident utilization at the provincial and regional level.

Health Outcomes and Cost Considerations of Assisted Peritoneal Dialysis: A Narrative Review

BACKGROUND

Peritoneal dialysis (PD) is underutilized in many parts of the world despite pro-PD health policies. The physical and cognitive demands of PD means that over half of eligible patients require some form of assistance. As such, many countries now offer assisted PD (aPD) programs to help patients start or stay on PD as opposed to in-center hemodialysis (HD). In order to evaluate the potential scope of aPD, it is important to review the outcomes and cost considerations of aPD.

SUMMARY

We reviewed available data from different countries and regions for health outcomes between aPD and in-center HD, with a focus on quality of life (QoL), mortality, hospitalization, and technique survival. We also evaluated studies discussing the overall costs of delivering aPD, including training, operating costs, and indirect costs and compared these to in-center HD costs for the same regions. Key Messages: aPD patients are older and more frail than either self-care PD patients and many in-center HD patients. We found no evidence for any difference in QoL, mortality, or hospitalization between aPD and in-center HD after adjustment for these differences. There is some evidence for an association between nurse assistance and improved technique survival as compared to family assistance or self-care PD. Despite increased cost of providing assistance in PD, it is still significantly less expensive than in-center HD in Western Europe and Canada.

COVID-19 in patients undergoing long-term dialysis in Ontario

BACKGROUND

Patients undergoing long-term dialysis may be at higher risk of infection with severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) and of associated disease and mortality. We aimed to describe the incidence, risk factors and outcomes for infection in these patients in Ontario, Canada.

METHODS

We used linked data sets to compare disease characteristics and mortality between patients receiving long-term dialysis in Ontario who were diagnosed SARS-CoV-2 positive and those who did not acquire SARS-CoV-2 infection, between Mar. 12 and Aug. 20, 2020. We collected data on SARS-CoV-2 infection prospectively. We evaluated risk factors for infection and death using multivariable logistic regression analyses.

RESULTS

During the study period, 187 (1.5%) of 12 501 patients undergoing dialysis were diagnosed with SARS-CoV-2 infection. Of those with SARS-CoV-2 infection, 117 (62.6%) were admitted to hospital and the case fatality rate was 28.3%. Significant predictors of infection included in-centre hemodialysis versus home dialysis (odds ratio [OR] 2.54, 95% confidence interval [CI] 1.59-4.05), living in a long-term care residence (OR 7.67, 95% CI 5.30-11.11), living in the Greater Toronto Area (OR 3.27, 95% CI 2.21-4.80), Black ethnicity (OR 3.05, 95% CI 1.95-4.77), Indian subcontinent ethnicity (OR 1.70, 95% CI 1.02-2.81), other non-White ethnicities (OR 2.03, 95% CI 1.38-2.97) and lower income quintiles (OR 1.82, 95% CI 1.15-2.89).

INTERPRETATION

Patients undergoing long-term dialysis are at increased risk of SARS-CoV-2 infection and death from coronavirus disease 2019. Special attention should be paid to addressing risk factors for infection, and these patients should be prioritized for vaccination.

Longitudinal Changes in the Use of PD Assistance for Patients Maintained on Peritoneal Dialysis

Background

Home dialysis therapies, such as peritoneal dialysis (PD), offer flexibility and improved well-being, particularly for older individuals. However, a substantial proportion require assistance with personal care and health care-related tasks. We hypothesized that patients and families would require less PD assistance as they became more familiar with PD-related tasks. The study objective was to assess whether the nature of, and need for, PD assistance decreased over time.

Methods

Using a multicentered, prospective, observational study design, patients aged ≥50 years were recruited from those starting PD. Patients underwent formal evaluation using validated components of a Comprehensive Geriatric Assessment at baseline, and they were followed monthly and administered a questionnaire about the need for assistance with PD-related tasks.

Results

A total of 111 patients (age 69±10 years, 68% men, and 56% diabetic) were followed for a total of 609 patient-months. Of those who needed help, 40% had help from a family member, and 33% were helped by nurses. Both the quantity and nature of help received by patients remained generally stable throughout follow-up and did not vary according to age, frailty, functional dependence, or cognitive impairment (P=0.93). The proportion of patients needing help varied widely across the 13 different tasks but appeared relatively stable across time. The paid-unpaid caregiver ratio for the different tasks did not change over time.

Conclusions

Older patients initiating PD in the outpatient setting have a high need for assistance with PD-related tasks, which seems to persist over the initial 6-month period.

Four steps to standardize reporting of peritoneal dialysis technique failure: A proposed approach

BACKGROUND

Technique failure is an important outcome measure in research and quality improvement in peritoneal dialysis (PD) programs, but there is a lack of consistency in how it is reported.

METHODS

We used data collected about incident dialysis patients from 10 Canadian dialysis programs between 1 January 2004 and 31 December 2018. We identified four main steps that are required when calculating the risk of technique failure. We changed one variable at a time, and then all steps, simultaneously, to determine the impact on the observed risk of technique failure at 24 months.

RESULTS

A total of 1448 patients received PD. Selecting different cohorts of PD patients changed the observed risk of technique failure at 24 months by 2%. More than one-third of patients who switched to hemodialysis returned to PD-90% returned within 180 days. The use of different time windows of observation for a return to PD resulted in risks of technique failure that differed by 16%. The way in which exit events were handled during the time window impacted the risk of technique failure by 4% and choice of statistical method changed results by 4%. Overall, the observed risk of technique failure at 24 months differed by 20%, simply by applying different approaches to the same data set.

CONCLUSIONS

The approach to reporting technique failure has an important impact on the observed results. We present a robust and transparent methodology to track technique failure over time and to compare performance between programs.

Peritoneal dialysis access outcomes reported in randomized controlled trials: A systematic review

BACKGROUND

Functional peritoneal dialysis (PD) access is critical to the success of PD therapy. The aim of this review is to describe the spectrum of definitions and methods employed in the measurement of unique outcomes across PD access trials particularly focusing on the outcomes of PD access flow restriction and operative-related outcomes.

METHODS

Using Cochrane CENTRAL registry, MEDLINE, and EMBASE, we searched for studies restricted to randomized controlled trials (RCTs) involving interventions related to PD access without restrictions on age, language, or publication year. Studies were screened and data abstracted by two independent reviewers. Definitions, outcome measures, and time points of measurements were captured and documented separately. Unique combinations of these variables resulted in reporting the different ways of measurements.

RESULTS

Of the 1768 screened studies, 47 RCTs were included among which 817 PD access outcomes were grouped into 7 broad categories. Interventions evaluated in the RCTs were catheter type/configuration (n = 17), insertion technique (n = 15), multiple interventions (n = 3), and other (6 interventions, n = 12). PD access flow restriction (a subcategory of mechanical outcomes) and operative-related outcomes were reported in 91% and 58% of the included trials, respectively. Tip migration was the most frequently reported flow restriction outcome (59% of RCTs) followed by catheter dysfunction (23% of RCTs). Of the components utilized in definition of flow restriction, description of the impaired flow was reported in 37% of RCTs, need for intervention in 42% of RCTs, and presumed etiology of flow restriction in 60% of RCTs.

CONCLUSION

Variability exists in the definitions, reporting methods, choice of outcomes, and analysis of the PD access outcomes across RCTs. Operative-related outcomes remain underreported across RCTs. Outcomes relating to PD access flow restriction were the most common complications reported in the included RCTs but were reported heterogeneously with variability in reporting of the three key components of its definition including description and severity of the flow restriction, the need for intervention and etiology of flow restriction. In the future, defining PD access flow restriction should include all of these components to better evaluate the comparative effect of various PD access interventions.

A Higher Concentration of Dialysate Magnesium to Reduce the Frequency of Muscle Cramps: A Narrative Review

Purpose of review:

Strategies to mitigate muscle cramps are a top research priority for patients receiving hemodialysis. As hypomagnesemia is a possible risk factor for cramping, we reviewed the literature to better understand the physiology of cramping as well as the epidemiology of hypomagnesemia and muscle cramps. We also sought to review the evidence from interventional studies on the effect of oral and dialysate magnesium-based therapies on muscle cramps.

Sources of information:

Peer-reviewed articles.

Methods:

We searched for relevant articles in major bibliographic databases including MEDLINE and EMBASE. The methodological quality of interventional studies was assessed using a modified version of the Downs and Blacks criteria checklist.

Key findings:

The etiology of muscle cramps in patients receiving hemodialysis is poorly understood and there are no clear evidence-based prevention or treatment strategies. Several factors may play a role including a low concentration of serum magnesium. The prevalence of hypomagnesemia (concentration of <0.7 mmol/L) in patients receiving hemodialysis ranges from 10% to 20%. Causes of hypomagnesemia include a low dietary intake of magnesium, use of medications that inhibit magnesium absorption (eg, proton pump inhibitors), increased magnesium excretion (eg, high-dose loop diuretics), and a low concentration of dialysate magnesium. Dialysate magnesium concentrations of ≤0.5 mmol/L may be associated with a decrease in serum magnesium concentration over time. Preliminary evidence from observational and interventional studies suggests a higher dialysate magnesium concentration will raise serum magnesium concentrations and may reduce the frequency and severity of muscle cramps. However, the quality of evidence supporting this benefit is limited, and larger, multicenter clinical trials are needed to further determine if magnesium-based therapy can reduce muscle cramps in patients receiving hemodialysis. In studies conducted to date, increasing the concentration of dialysate magnesium appears to be well-tolerated and is associated with a low risk of symptomatic hypermagnesemia.

Limitations:

Few interventional studies have examined the effect of magnesium-based therapy on muscle cramps in patients receiving hemodialysis and most were nonrandomized, pre-post study designs.

Sex differences in the vascular access of hemodialysis patients: a cohort study

Background

We describe differences for probability of receiving a fistula attempt, achieving fistula use, remaining catheter-free and the rate of access-related procedures as a function of sex.

Methods

Prospectively collected vascular access data on incident dialysis patients from five Canadian programs using the Dialysis Measurement Analysis and Reporting System to determine differences in fistula-related outcomes between women and men. The probability of receiving a fistula attempt and the probability of fistula use were determined using binary logistic regression. Catheter and fistula procedure rates were described using Poisson regression. We studied time to fistula attempt and time to fistula use, accounting for competing risks.

Results

We included 1446 (61%) men and 929 (39%) women. Men had a lower body mass index (P < 0.001) and were more likely to have coronary artery disease (P < 0.001) and peripheral vascular disease (p < 0.001). A total of 688 (48%) men and 403 (43%) women received a fistula attempt. Women were less likely to receive a fistula attempt by 6 months {odds ratio [OR] 0.64 [95% confidence interval (CI) 0.52-0.79]} and to achieve catheter-free use of their fistula by 1 year [OR 0.38 (95% CI 0.27-0.53)]. At an average of 2.30 access procedures per person-year, there is no difference between women and men [incidence rate ratio (IRR) 0.97 (95% CI 0.87-1.07)]. Restricting to those with a fistula attempt, women received more procedures [IRR 1.16 (95% CI 1.04-1.30)] attributed to increased catheter procedures [IRR 1.50 (95% CI 1.27-1.78)]. There was no difference in fistula procedures [IRR women versus men 0.96 (95% CI 0.85-1.07)].

Conclusion

Compared with men, fewer women undergo a fistula attempt. This disparity increases after adjusting for comorbidities. Women have the same number of fistula procedures as men but are less likely to successfully use their fistula.

Comparative migration ecology of striped bass and Atlantic sturgeon in the US Southern mid-Atlantic bight flyway

Seasonal migrations are key to the production and persistence of marine fish populations but movements within shelf migration corridors or, “flyways”, are poorly known. Atlantic sturgeon and striped bass, two critical anadromous species, are known for their extensive migrations along the US Mid-Atlantic Bight. Seasonal patterns of habitat selection have been described within spawning rivers, estuaries,and shelf foraging habitats, but information on the location and timing of key coastal migrations is limited. Using a gradient-based array of acoustic telemetry receivers, we compared the seasonal incidence and movement behavior of these species in the near-shelf region of Maryland, USA. Atlantic sturgeon incidence was highest in the spring and fall and tended to be biased toward shallow regions, while striped bass had increased presence during spring and winter months and selected deeper waters. Incidence was transient (mean = ~2 d) for both species with a pattern of increased residency (>2 d) during autumn and winter, particularly for striped bass, with many individuals exhibiting prolonged presence on the outer shelf during winter. Flyways also differed spatially between northern and southern migrations for both species and were related to temperature: striped bass were more likely to occur in cool conditions while Atlantic sturgeon preferred warmer temperatures. Observed timing and spatial distribution within the Mid-Atlantic flyway were dynamic between years and sensitive to climate variables. As shelf ecosystems come under increasing maritime development, gridded telemetry designs represent a feasible approach to provide impact responses within key marine flyways like those that occur within the US Mid-Atlantic Bight.

Quantifying the risk of insertion-related peritoneal dialysis catheter complications following laparoscopic placement: Results from the North American PD Catheter Registry

BACKGROUND

Peritoneal dialysis (PD) is a more cost-effective therapy to treat kidney failure than in-center hemodialysis, but successful therapy requires a functioning PD catheter that causes minimal complications. In 2015, the North American Chapter of the International Society for Peritoneal Dialysis established the North American PD Catheter Registry to improve practices and patient outcomes following PD catheter insertion.

AIMS

The objective of this study is to propose a methodology for defining insertion-related complications that lead to significant adverse events and report the risk of these complications among patients undergoing laparoscopic PD catheter insertion.

METHODS

Patients undergoing laparoscopic PD catheter insertion were enrolled at 14 participating centers in Canada and the United States and followed using a Web-based registry. Insertion-related complications were defined as flow restriction, exit-site leak, or abdominal pain at any point during follow-up. We also included infections or bleeding within 30 days of insertion, and any immediate postoperative complications. Adverse events were categorized as PD never starting or termination of PD therapy, delay in the start of PD therapy or interruption of PD therapy, an emergency department visit or hospitalization, or need for invasive procedures. Cause-specific cumulative incidence functions were used to estimate risk.

RESULTS

Five hundred patients underwent laparoscopic PD catheter insertion between 10 November 2015 and 24 July 2018. The cumulative risk of insertion-related complications 6 months from the date of insertion that led to an adverse event was 24%. The risk of flow restriction, exit-site leak, and pain at 6 months was 10.2%, 5.7%, and 5.3%, respectively. PD was never started or terminated in 6.4% of patients due to an insertion-related complication. Leaks and flow restrictions were most likely to delay or interrupt PD therapy. Flow restrictions were the primary cause of invasive procedures. Fifty percent of the complications occurred before the start of PD therapy.

CONCLUSIONS

Insertion-related complications leading to significant adverse events following laparoscopic placement of PD catheters are common. Many complications occur before the start of PD. Insertion-related complications are an important area of focus for future research and quality improvement efforts.