Trends in emergency department visits during cold weather seasons among patients experiencing homelessness in Ontario, Canada: a retrospective population-based cohort study

PURPOSE

Recent anecdotal reports suggest increasing numbers of people experiencing homelessness are visiting emergency departments (EDs) during cold weather seasons due to inadequate shelter availability. We examined monthly ED visits among patients experiencing homelessness to determine whether there has been a significant increase in such visits in 2022/2023 compared to prior years.

METHODS

We used linked health administrative data to identify cohorts experiencing homelessness in Ontario between October and March of the 2018/2019 to 2022/2023 years. We analyzed the monthly rate of non-urgent ED visits as a proxy measure of visits plausibly attributable to avoidance of cold exposure, examining rates among patients experiencing homelessness compared to housed patients. We excluded visits for overdose or COVID-19. We assessed level and significance of change in the 2022/2023 year as compared to previous cold weather seasons using Poisson regression.

RESULTS

We identified a total of 21,588 non-urgent ED visits across the observation period among patients experiencing homelessness in Ontario. Non-urgent ED visits increased 27% (RR 1.24 [95% CI 1.14-1.34]) in 2022/2023 compared to previous cold weather seasons. In Toronto, such visits increased by 70% (RR 1.68 [95% CI 1.57-1.80]). Among housed patients, non-urgent ED visits did not change significantly during this time period.

CONCLUSION

Rates of ED visits plausibly attributable to avoidance of cold exposure by individuals experiencing homelessness increased significantly in Ontario in 2022/2023, most notably in Toronto. This increase in ED visits may be related to inadequate access to emergency shelter beds and warming services in the community.

The safety of seasonal influenza vaccination among adults prescribed immune checkpoint inhibitors: A self-controlled case series study using administrative data

BACKGROUND

Immune checkpoint inhibitor (ICI) therapy for patients undergoing cancer treatment carries a risk of severe immune-related adverse events (IRAEs). Questions remain about whether seasonal influenza vaccination might increase the risk of developing IRAEs among these patients given that vaccines are immunomodulatory. Previous vaccine safety studies on patients with cancer prescribed ICI therapy have demonstrated conflicting results.

METHODS

Using health administrative data from Ontario, Canada among adults diagnosed with cancer who had been prescribed ICI therapy and who had received an influenza vaccine from 2012 to 2019, we conducted a self-controlled case series study. The pre-vaccination control period started 42-days post-ICI initiation until 14-days prior to vaccination, the risk period was 1-42 days post-vaccination, and the post-vaccination control period was after the risk period until ICI discontinuation or a maximum period of two years. Emergency department (ED) visit(s) and/or hospitalization for any cause after ICI initiation was used to identify severe IRAEs. We fitted a fixed-effects Poisson regression model accounting for seasonality and calendar time to estimate relative incidence of IRAEs between risk and control periods.

RESULTS

We identified 1133 records of cancer patients who received influenza vaccination while prescribed ICI therapy. Most were aged ≥ 66 years (73 %), were male (63 %), had lung cancer (54 %), and had received ICI therapy with a programmed cell death protein 1(PD-1) inhibitor (91 %). A quarter (26 %) experienced an ED visit and/or hospitalization during the observation period. Rates of ED visits and/or hospitalizations in the risk vs. control periods were similar, with an incidence rate ratio of 1.04 (95 % CI: 0.75-1.45). Subgroup and sensitivity analyses yielded similar results.

CONCLUSION

Seasonal influenza vaccination was not associated with an increased incidence of ED visit or hospitalization among adults with cancer treated with ICI therapy and our results support further evidence of vaccine safety.

Treatment and Mortality Following Cancer Diagnosis Among People With Non-affective Psychotic Disorders in Ontario, Canada: A Retrospective Cohort Study

BACKGROUND AND HYPOTHESIS

People with psychotic disorders have a higher risk of mortality following cancer diagnosis, compared to people without psychosis. The extent to which this disparity is influenced by differences in cancer-related treatment is currently unknown. We hypothesized that, following a cancer diagnosis, people with psychotic disorders were less likely to receive treatment and were at higher risk of death than those without psychosis.

STUDY DESIGN

We constructed a retrospective cohort of cases of non-affective psychotic disorder (NAPD) and a general population comparison group, using Ontario Health (OH) administrative data. We identified cases of all cancers diagnosed between 1995 and 2019 and obtained information on cancer-related treatment and mortality. Cox proportional hazards models were used to compare the probability of having a consultation with an oncologist and receiving cancer-related treatment, adjusting for tumor site and stage. We also compared the rate of all-cause and cancer-related mortality between the two groups, adjusting for tumor site.

STUDY RESULTS

Our analytic sample included 24 944 people diagnosed with any cancer. People with NAPD were less likely to receive treatment than people without psychosis (HR = 0.87, 95% CI = 0.82, 0.91). In addition, people with NAPD had a greater risk of death from any cause (HR = 1.68, 95% CI = 1.60, 1.76), compared to people without NAPD.

CONCLUSIONS

The lower likelihood of receiving cancer treatment reflects disparities in accessing cancer care for people with psychotic disorders, which may partially explain the higher mortality risk following cancer diagnosis. Future research should explore mediating factors in this relationship to identify targets for reducing health disparities.

Enhancing detection of SARS-CoV-2 re-infections using longitudinal sero-monitoring: demonstration of a methodology in a cohort of people experiencing homelessness in Toronto, Canada

BACKGROUND

Accurate estimation of SARS-CoV-2 re-infection is crucial to understanding the connection between infection burden and adverse outcomes. However, relying solely on PCR testing results in underreporting. We present a novel approach that includes longitudinal serologic data, and compared it against testing alone among people experiencing homelessness.

METHODS

We recruited 736 individuals experiencing homelessness in Toronto, Canada, between June and September 2021. Participants completed surveys and provided saliva and blood serology samples every three months over 12 months of follow-up. Re-infections were defined as: positive PCR or rapid antigen test (RAT) results > 90 days after initial infection; new serologic evidence of infection among individuals with previous infection who sero-reverted; or increases in anti-nucleocapsid in seropositive individuals whose levels had begun to decrease.

RESULTS

Among 381 participants at risk, we detected 37 re-infections through PCR/RAT and 98 re-infections through longitudinal serology. The comprehensive method identified 37.4 re-infection events per 100 person-years, more than four-fold more than the rate detected through PCR/RAT alone (9.0 events/100 person-years). Almost all test-confirmed re-infections (85%) were also detectable by longitudinal serology.

CONCLUSIONS

Longitudinal serology significantly enhances the detection of SARS-CoV-2 re-infections. Our findings underscore the importance and value of combining data sources for effective research and public health surveillance.

Self-reported tick exposure as an indicator of Lyme disease risk in an endemic region of Quebec, Canada

BACKGROUND

Lyme disease (LD) and other tick-borne diseases are emerging across Canada. Spatial and temporal LD risk is typically estimated using acarological surveillance and reported human cases, the former not considering human behavior leading to tick exposure and the latter occurring after infection.

OBJECTIVES

The primary objective was to explore, at the census subdivision level (CSD), the associations of self-reported tick exposure, alternative risk indicators (predicted tick density, eTick submissions, public health risk level), and ecological variables (Ixodes scapularis habitat suitability index and cumulative degree days > 0 °C) with incidence proportion of LD. A secondary objective was to explore which of these predictor variables were associated with self-reported tick exposure at the CSD level.

METHODS

Self-reported tick exposure was measured in a cross-sectional populational health survey conducted in 2018, among 10,790 respondents living in 116 CSDs of the Estrie region, Quebec, Canada. The number of reported LD cases per CSD in 2018 was obtained from the public health department. Generalized linear mixed-effets models accounting for spatial autocorrelation were built to fulfill the objectives.

RESULTS

Self-reported tick exposure ranged from 0.0 % to 61.5 % (median 8.9 %) and reported LD incidence rates ranged from 0 to 324 cases per 100,000 person-years, per CSD. A positive association was found between self-reported tick exposure and LD incidence proportion (ß = 0.08, CI = 0.04,0.11, p < 0.0001). The best-fit model included public health risk level (AIC: 144.2), followed by predicted tick density, ecological variables, self-reported tick exposure and eTick submissions (AIC: 158.4, 158.4, 160.4 and 170.1 respectively). Predicted tick density was the only significant predictor of self-reported tick exposure (ß = 0.83, CI = 0.16,1.50, p = 0.02).

DISCUSSION

This proof-of-concept study explores self-reported tick exposure as a potential indicator of LD risk using populational survey data. This approach may offer a low-cost and simple tool for evaluating LD risk and deserves further evaluation.

A registry-based population study of the HLA in Québec, Canada

As part of the worldwide effort to better characterize HLA diversity in populations, we have studied the population of Québec in Canada. This province has been defined by a complex history with multiple founder effects and migration patterns. We analyzed the typing data of 3806 individuals registered in Héma-Québec's Registry, which covered most administrative regions in Québec. Typing information was resolved at the second field level of resolution by next-generation sequencing (NGS) or by Sanger sequencing. We used the HLA-net.eu GENE[RATE] tools to estimate allele and two-locus haplotype frequencies for HLA-A, -B, -C, -DRB1, -DQB1, and -DPB1, as well as Hardy-Weinberg equilibrium (HWE), selective neutrality, and linkage disequilibrium. The chord genetic distance was also calculated between administrative regions and was visualized using non-metric multidimensional scaling (NMDS) analysis. While most individual regions were in HWE, HWE was rejected for the province considered as a whole. Some regions exhibited signatures of selection, mostly toward an excess of heterozygotes. Allele and haplotype frequencies revealed outlier regions that strongly differed from the other regions. NMDS plots also showed differences between regions. The administrative regions of the province of Québec displayed heterogeneity in their HLA profiles. This heterogeneity was attributable to differing allele and haplotype specificities by region. In particular, regions 02-Saguenay-Lac-Saint-Jean and 01-Bas-St-Laurent diverged from the rest of the regions. The urban regions 06-Montréal and 13-Laval were very diversified in their HLA profiles. Together, these results will help optimize donor recruitment strategies in Québec.

Trends in hospital coding for people experiencing homelessness in Canada, 2015-2020: a descriptive study

BACKGROUND

In 2018, hospitals were mandated to record homelessness using International Statistical Classification of Diseases and Related Health Problems, 10th Revision, Canada (ICD-10-CA code Z59.0). We sought to answer whether the coding mandate affected the volume of patients identified as experiencing homelessness in acute inpatient hospitalizations and if there was any geographic variation.

METHODS

We conducted a serial cross-sectional study describing 6 fiscal years (2015/16 to 2020/21) of hospital administrative data from the Hospital Morbidity Database. We reported frequencies and percentages of hospitalizations with a Z59.0 diagnostic code and disaggregated by several types of Canadian geographies. Controlling for fiscal quarter (coded Q1 to Q4) and province or territory, adjusted logistic regression models quantified the odds of Z59.0 being coded during hospital stays.

RESULTS

The frequency and percentage of people experiencing homelessness in hospitalization records across Canada increased from 6934 (0.12%) in 2015/16 to 21 529 (0.41%) in 2020/21. Trends varied by province and territory. Recording of the Z59.0 code increased following the mandate (adjusted odds ratio 2.29, 95% confidence interval 2.25-2.32), relative to the pre-mandate period.

INTERPRETATION

The 2018 coding mandate coincided with an increase in the use of the Z59.0 code to document homelessness in health care administrative data; however, trends varied by jurisdiction. The ICD-10-CA code Z59.0 presents a promising opportunity for standardized and routinely collected data to identify people experiencing homelessness in hospital administrative data.

The burden of psychiatric disorders associated with orofacial cleft pathology among children in Ontario, Canada

BACKGROUND

Individuals with orofacial cleft (OFC) may be at a higher risk of developing psychiatric disorders (PD) than the general population. We determined the risk of psychiatric diagnoses in children with OFC in Canada.

METHODS

This population-based retrospective cohort study used health administrative data from the province of Ontario, Canada. Children with OFC who were born between April 1, 1994, and March 31, 2017, in Ontario were matched to five non-OFC children based on sex, date of birth, and mother's age. We determined the rate of events and time-to-event for first diagnosis of PD in children aged ≥ 3 years (y), and for intellectual developmental delay (IDD) from birth. Risk factors for PD and IDD were assessed using 1-way ANOVA for means, Kruskal-Wallis for medians, and the χ2 test for categorical variables.

OUTCOMES

There were 3051 children with OFC (matched to 15,255 controls), of whom 2515 patients with OFC (12,575 controls) had a complete follow-up to the third birthday. Children with OFC were more likely to have PD than controls (54.90 vs. 43.28 per 1000 patient-years, P < .001), with a mean age to first diagnosis of 8.6 ± 4.2 y. The cleft palate group had the highest risk (HR 1.33, 95% CI 1.18-1.49). Children with OFC also had a higher risk of IDD than non-OFC children (27.78 vs. 3.46 per 1000 patient-years, p < .001).

INTERPRETATION

Children born with OFC in Ontario had a higher risk of psychiatric diagnosis and IDD compared to controls. Further research is also required to better understand the predictors of variation in risk, including geographic location and the presence of congenital abnormalities, and identify potential areas for intervention.

EVIDENCE RATING SCALE FOR PROGNOSTIC/RISK STUDIES

Level II.

Professional characteristics, attitudes, and practices associated with stress and quality of life among Canadian animal health workers

Objective

To describe the knowledge, attitudes, and practices (KAP) towards COVID-19 of Canadian companion animal health workers (AHW); to measure their perceived stress and quality of life (QoL); and to explore professional risk factors associated with stress and QoL.

Sample

We sampled 436 companion animal veterinarians and technicians.

Procedure

The study had cross-sectional and cohort components. It was conducted online in August to December 2020, and repeated in May to July 2021, using a questionnaire assessing the respondents' professional characteristics, COVID-19 KAP, perceived stress, and QoL.

Results

Overall, AHW had sufficient knowledge of COVID-19 transmission, and reported having adopted good preventive practices. Since the beginning of the pandemic, participants reported increases in new clients (76%), in refusal of new clients (53%), and in pet euthanasia (24%). Increased client refusal and pet euthanasia were associated with greater stress and poorer professional QoL, whereas perceived susceptibility to and adoption of measures against COVID-19 were associated with lower stress and better QoL.

Conclusion and clinical relevance

For AHW, professional characteristics were associated with stress and professional QoL. This information is important for developing strategies to cope with the ongoing shortage of AHW and with future public health crises.

Epilepsy Surgery in Adult Stroke Survivors with New-Onset Drug-Resistant Epilepsy

BACKGROUND

Despite its effectiveness, surgery for drug-resistant epilepsy is underutilized. However, whether epilepsy surgery is also underutilized among patients with stroke-related drug-resistant epilepsy is unclear. Therefore, our objectives were to estimate the rates of epilepsy surgery assessment and receipt among patients with stroke-related drug-resistant epilepsy and to identify factors associated with these outcomes.

METHODS

We used linked health administrative databases to conduct a population-based retrospective cohort study of adult Ontario, Canada residents discharged from an Ontario acute care institution following the treatment of a stroke between January 1, 1997, and December 31, 2020, without prior evidence of seizures. We excluded patients who did not subsequently develop drug-resistant epilepsy and those with other epilepsy risk factors. We estimated the rates of epilepsy surgery assessment and receipt by March 31, 2021. We planned to use Fine-Gray subdistribution hazard models to identify covariates independently associated with our outcomes, controlling for the competing risk of death.

RESULTS

We identified 265,081 patients who survived until discharge following inpatient stroke treatment, 1,902 (0.7%) of whom subsequently developed drug-resistant epilepsy (805 women; mean age: 67.0 ± 13.1 years). Fewer than six (≤0.3%) of these patients were assessed for or received epilepsy surgery before the end of follow-up (≤55.5 per 100,000 person-years). Given that few outcomes were identified, we could not proceed with the multivariable analyses.

CONCLUSIONS

Patients with stroke-related drug-resistant epilepsy are infrequently considered for epilepsy surgery that could reduce morbidity and mortality.

Early mortality in patients with cancer treated with immune checkpoint inhibitors in routine practice

BACKGROUND

We sought to estimate the proportion of patients with cancer treated with immune checkpoint inhibitors (ICI) who die soon after starting ICI in the real world and examine factors associated with early mortality (EM).

METHODS

We conducted a retrospective cohort study using linked health administrative data from Ontario, Canada. EM was defined as death from any cause within 60 days of ICI initiation. Patients with melanoma, lung, bladder, head and neck, or kidney cancer treated with ICI between 2012 and 2020 were included.

RESULTS

A total of 7126 patients treated with ICI were evaluated. Fifteen percent (1075 of 7126) died within 60 days of initiating ICI. The highest mortality was observed in patients with bladder and head and neck tumors (approximately 21% each). In multivariable analysis, previous hospital admission or emergency department visit, prior chemotherapy or radiation therapy, stage 4 disease at diagnosis, lower hemoglobin, higher white blood cell count, and higher symptom burden were associated with higher risk of EM. Conversely, patients with lung and kidney cancer (compared with melanoma), lower neutrophil to lymphocytes ratio, and with higher body mass index were less likely to die within 60 days post ICI initiation. In a sensitivity analysis, 30-day and 90-day mortality were 7% (519 of 7126) and 22% (1582 of 7126), respectively, with comparable clinical factors associated with EM identified.

CONCLUSIONS

EM is common among patients treated with ICI in the real-world setting and is associated with several patient and tumor characteristics. Development of a validated tool to predict EM may facilitate better patient selection for treatment with ICI in routine practice.

Cold-related injuries among patients experiencing homelessness in Toronto: a descriptive analysis of emergency department visits

PURPOSE

Homelessness increases the risk of cold-related injuries. We examined emergency department visits for cold-related injuries in Toronto over a 4-year period, comparing visits for patients identified as homeless to visits for patients not identified as homeless.

METHODS

This descriptive analysis of visits to emergency departments in Toronto between July 2018 and June 2022 used linked health administrative data. We measured emergency department visits with cold-related injury diagnoses among patients experiencing homelessness and those not identified as homeless. Rates were expressed as a number of visits for cold-related injury per 100,000 visits overall. Rate ratios were used to compare rates between homeless vs. not homeless groups.

RESULTS

We identified 333 visits for cold-related injuries among patients experiencing homelessness and 1126 visits among non-homeless patients. In each of the 4 years of observation, rate ratios ranged between 13.6 and 17.6 for cold-related injuries overall, 13.7 and 17.8 for hypothermia, and 10.3 and 18.3 for frostbite. Rates per 100,000 visits in the fourth year (July 2021 to June 2022) were significantly higher than in the pre-pandemic period. Male patients had higher rates, regardless of homelessness status; female patients experiencing homelessness had higher rate ratios than male patients experiencing homelessness.

CONCLUSION

Patients experiencing homelessness visiting the emergency department are much more likely to be seen for cold-related injuries than non-homeless patients. Additional efforts are needed to prevent cold-related exposure and consequent injury among people experiencing homelessness.

A Cross-Sectional Study of Community-Level Physician Retention and Diabetes Management in Rural Ontario

OBJECTIVE

To examine the impact of community-level physician retention on the quality of diabetes care in rural Ontario.

METHODS

Using administrative data, we compared diabetes quality of care. We defined retention as the proportion of physicians in a community from one year to the next. We grouped retention level by tertile and added a category for communities with no physician.

RESULTS

Residents of high retention communities were more likely to have HbA1C (1.10;95%CI:1.06-1.14) and LDL testing (1.17;95%CI:1.13-1.22), but less likely to have UACR testing (0.86;95%CI:0.83-0.89) or receive ACE/ARBs (0.91;95%CI:0.86-0.95) or statins (0.91;95%CI:0.87-0.96) than low retention communities. Communities with no residing physician had care that was equivalent to or better than high-retention communities.

DISCUSSION

Community-level physician retention, based on a two-year time frame, was significantly related.

Incidence of SARS-CoV-2 Infection Among People Experiencing Homelessness in Toronto, Canada

IMPORTANCE

People experiencing homelessness are at high risk of SARS-CoV-2 infection. Incident infection rates have yet to be established in these communities and are needed to inform infection prevention guidance and related interventions.

OBJECTIVE

To quantify the SARS-CoV-2 incident infection rate among people experiencing homelessness in Toronto, Canada, in 2021 and 2022 and to assess factors associated with incident infection.

DESIGN, SETTING, AND PARTICIPANTS

This prospective cohort study was conducted among individuals aged 16 years and older who were randomly selected between June and September 2021 from 61 homeless shelters, temporary distancing hotels, and encampments in Toronto, Canada.

EXPOSURES

Self-reported housing characteristics, such as number sharing living space.

MAIN OUTCOMES AND MEASURES

Prevalence of prior SARS-CoV-2 infection in summer 2021, defined as self-reported or polymerase chain reaction (PCR)- or serology-confirmed evidence of infection at or before the baseline interview, and SARS-CoV-2 incident infection, defined as self-reported or PCR- or serology-confirmed infection among participants without history of infection at baseline. Factors associated with infection were assessed using modified Poisson regression with generalized estimating equations.

RESULTS

The 736 participants (415 of whom did not have SARS-CoV-2 infection at baseline and were included in the primary analysis) had a mean (SD) age of 46.1 (14.6) years; 486 (66.0%) self-identified as male. Of these, 224 (30.4% [95% CI, 27.4%-34.0%]) had a history of SARS-CoV-2 infection by summer 2021. Of the remaining 415 participants with follow-up, 124 experienced infection within 6 months, representing an incident infection rate of 29.9% (95% CI, 25.7%-34.4%), or 5.8% (95% CI, 4.8%-6.8%) per person-month. Report after onset of the SARS-CoV-2 Omicron variant was associated with incident infection, with an adjusted rate ratio (aRR) of 6.28 (95% CI, 3.94-9.99). Other factors associated with incident infection included recent immigration to Canada (aRR, 2.74 [95% CI, 1.64-4.58]) and alcohol consumption over the past interval (aRR, 1.67 [95% CI, 1.12-2.48]). Self-reported housing characteristics were not significantly associated with incident infection.

CONCLUSIONS AND RELEVANCE

In this longitudinal study of people experiencing homelessness in Toronto, SARS-CoV-2 incident infection rates were high in 2021 and 2022, particularly once the Omicron variant became dominant in the region. Increased focus on homelessness prevention is needed to more effectively and equitably protect these communities.

HLA and red blood cell antigen genotyping in SARS-CoV-2 convalescent plasma donors

Aim: More data is required regarding the association between HLA allele and red blood cell (RBC) antigen expression in regard to SARS-CoV-2 infection and COVID-19 susceptibility. Methods: ABO, RhD, 37 other RBC antigens and HLA-A, B, C, DRB1, DQB1 and DPB1 were determined using high throughput platforms in 90 Caucasian convalescent plasma donors. Results: The AB group was significantly increased (1.5×, p = 0.018) and some HLA alleles were found to be significantly overrepresented (HLA-B*44:02, C*05:01, DPB1*04:01, DRB1*04:01 and DRB1*07:01) or underrepresented (A*01:01, B51:01 and DPB1*04:02) in convalescent individuals compared with the local bone marrow registry population. Conclusion: Our study of infection-susceptible but non-hospitalized Caucasian COVID-19 patients contributes to the global understanding of host genetic factors associated with SARS-CoV-2 infection and severity.

Navigator programme for hospitalised adults experiencing homelessness: protocol for a pragmatic randomised controlled trial

INTRODUCTION

People experiencing homelessness suffer from poor outcomes after hospitalisation due to systemic barriers to care, suboptimal transitions of care, and intersecting health and social burdens. Case management programmes have been shown to improve housing stability, but their effects on broad posthospital outcomes in this population have not been rigorously evaluated. The Navigator Programme is a Critical Time Intervention case management programme that was developed to help homeless patients with their postdischarge needs and to link them with community-based health and social services. This randomised controlled trial examines the impact of the Navigator Programme on posthospital outcomes among adults experiencing homelessness.

METHODS AND ANALYSIS

This is a pragmatic randomised controlled trial testing the effectiveness of the Navigator Programme at an urban academic teaching hospital and an urban community teaching hospital in Toronto, Canada. Six hundred and forty adults experiencing homelessness who are admitted to the hospital will be randomised to receive support from a Homeless Outreach Counsellor for 90 days after hospital discharge or to usual care. The primary outcome is follow-up with a primary care provider (physician or nurse practitioner) within 14 days of hospital discharge. Secondary outcomes include postdischarge mortality or readmission, number of days in hospital, number of emergency department visits, self-reported care transition quality, and difficulties meeting subsistence needs. Quantitative outcomes are being collected over a 180-day period through linked patient-reported and administrative health data. A parallel mixed-methods process evaluation will be conducted to explore intervention context, implementation and mechanisms of impact.

ETHICS AND DISSEMINATION

Ethics approval was obtained from the Unity Health Toronto Research Ethics Board. Participants will be required to provide written informed consent. Results of the main trial and process evaluation will be reported in peer-reviewed journals and shared with hospital leadership, community partners and policy makers.

TRIAL REGISTRATION NUMBER

NCT04961762.

Virtual family physician care during COVID-19: a mixed methods study using health administrative data and qualitative interviews

BACKGROUND

The onset of the COVID-19 pandemic necessitated a rapid shift in primary health care from predominantly in-person to high volumes of virtual care. The pandemic afforded the opportunity to conduct a deep regional examination of virtual care by family physicians in London and Middlesex County, Ontario, Canada that would inform the foundation for virtual care in our region post-pandemic.

OBJECTIVES

(1) to determine volumes of in-person and virtual family physicians visits and characteristics of the family physicians and patients using them during the early COVID-19 pandemic; (2) to determine how virtual visit volumes changed over the pandemic, compared to in-person; and (3) to explore family physicians' experience in virtual visit adoption and implementation.

METHODS

We conducted a concurrent mixed-methods study of family physicians from March to October 2020. The quantitative component examined mean weekly number of total, in-person and virtual visits using health administrative data. Differences in outcomes according to physician and practice characteristics for pandemic periods were compared to pre-pandemic. The qualitative study employed Constructivist Grounded Theory, conducting semi-structured family physicians interviews; analyzing data iteratively using constant comparative analysis. We mapped themes from the qualitative analysis to quantitative findings.

RESULTS

Initial volumes of patients decreased, driven by fewer in-person visits. Virtual visit volumes increased dramatically; family physicians described using telephone almost entirely. Rural family physicians reported video connectivity issues. By early second wave, total family physician visit volume returned to pre-pandemic volumes. In-person visits increased substantially; family physicians reported this happened because previously scarce personal protective equipment became available. Patients seen during the pandemic were older, sicker, and more materially deprived.

CONCLUSION

These results can inform the future of virtual family physician care including the importance of continued virtual care compensation, the need for equitable family physician payment models, and the need to attend to equity for vulnerable patients. Given the move to virtual care was primarily a move to telephone care, the modality of care delivery that is acceptable to both family physicians and their patients must be considered.

Dissecting the impact of molecular T-cell HLA mismatches in kidney transplant failure: A retrospective cohort study

Introduction

Kidney transplantation is the optimal treatment in end-stage kidney disease, but de-novo donor specific antibody development continues to negatively impact patients undergoing kidney transplantation. One of the recent advances in solid organ transplantation has been the definition of molecular mismatching between donors and recipients' Human Leukocyte Antigens (HLA). While not fully integrated in standard clinical care, cumulative molecular mismatch at the level of eplets (EMM) as well as the PIRCHE-II score have shown promise in predicting transplant outcomes. In this manuscript, we sought to study whether certain T-cell molecular mismatches (TcEMM) were highly predictive of death-censored graft failure (DCGF).

Methods

We studied a retrospective cohort of kidney donor:recipient pairs from the Scientific Registry of Transplant Recipients (2000-2015). Allele level HLA-A, B, C, DRB1 and DQB1 types were imputed from serologic types using the NMDP algorithm. TcEMMs were then estimated using the PIRCHE-II algorithm. Multivariable Accelerated Failure Time (AFT) models assessed the association between each TcEMM and DCGF. To discriminate between TcEMMs most predictive of DCGF, we fit multivariable Lasso penalized regression models. We identified co-expressed TcEMMs using weighted correlation network analysis (WGCNA). Finally, we conducted sensitivity analyses to address PIRCHE and IMGT/HLA version updates.

Results

A total of 118,309 donor:recipient pairs meeting the eligibility criteria were studied. When applying the PIRCHE-II algorithm, we identified 1,935 distinct TcEMMs at the population level. A total of 218 of the observed TcEMM were independently associated with DCGF by AFT models. The Lasso penalized regression model with post selection inference identified a smaller subset of 86 TcEMMs (56 and 30 TcEMM derived from HLA Class I and II, respectively) to be highly predictive of DCGF. Of the observed TcEMM, 38.14% appeared as profiles of highly co-expressed TcEMMs. In addition, sensitivity analyses identified that the selected TcEMM were congruent across IMGT/HLA versions.

Conclusion

In this study, we identified subsets of TcEMMs highly predictive of DCGF and profiles of co-expressed mismatches. Experimental verification of these TcEMMs determining immune responses and how they may interact with EMM as predictors of transplant outcomes would justify their consideration in organ allocation schemes and for modifying immunosuppression regimens.

Epilepsy Risk Following Bariatric Surgery for Weight Loss

BACKGROUND AND OBJECTIVES

A previous study reported finding that epilepsy risk is elevated following bariatric surgery for weight loss; however, this association has not been adequately explored. Our objectives were to (1) estimate the risk of epilepsy following bariatric surgery for weight loss relative to a non-surgical cohort of patients with an obesity diagnosis, and (2) identify epilepsy risk factors among bariatric surgery recipients.

METHODS

We conducted a population-based retrospective cohort study using linked health administrative databases in Ontario, Canada. Participants were accrued between July 1, 2010, and December 31, 2016, and followed until December 31, 2019. All Ontario residents 18 years of age and older who had bariatric surgery during the accrual period were eligible for inclusion in our exposed cohort. Patients hospitalized with a diagnosis of obesity and who did not have bariatric surgery during the accrual period were eligible for inclusion in our unexposed cohort. We excluded patients with a history of seizures, epilepsy, various seizure or epilepsy risk factors, psychiatric disorders, or drug or alcohol abuse/dependence. In our primary analysis, we used inverse probability of treatment weighting to control for confounding. A marginal Cox proportional hazards model was then used to estimate the risk of epilepsy associated with bariatric surgery. A Cox model was also used to identify epilepsy risk factors among exposed participants.

RESULTS

The final sample included 16,958 exposed participants and 622,514 unexposed participants. Following inverse probability of treatment weighting, the estimated rates of epilepsy were 50.1 and 34.1 per 100,000 person-years among those who did and did not have bariatric surgery, respectively. The hazard ratio for developing epilepsy after bariatric surgery was 1.45 (95% CI=1.35, 1.56). Among participants who received bariatric surgery, stroke during follow-up increased epilepsy risk (HR=14.03, 95% CI=4.26, 46.25).

DISCUSSION

In this study, we found that patients with a history of bariatric surgery were at increased risk of developing epilepsy. These findings suggest that epilepsy is a long-term risk associated with bariatric surgery for weight loss.

Abstract 28 Comparative Analysis of the Cord Blood Bank in Quebec

Introduction

In the context of the regional diversity observed in the population of Quebec, the Héma-Québec Cord Blood Bank (HQ CBB) representation differs from that of the Héma-Québec Stem Cell Registry (HQ Registry). The Bank encourages registrants of non-European descent to promote diversity, and only collects from health centers around Montreal and Quebec cities because of proximity concerns.

Objective

In this study, we aimed to analyze allele frequencies in the HQ CBB to assess similarities and differences in reference to the HQ Registry.

Methods

The HQ Registry was previously typed using high-resolution genotyping. For the HQ CBB, ambiguous two-field HLA-A, -B, -C, and -DRB1 typing data were obtained from cord blood units. Statistical analyses were performed using the GENE[RATE] population analysis tools to estimate allele and haplotype frequencies by administrative region determined by registered postal codes. Hardy-Weinberg equilibrium was verified by the nested likelihood procedure. Finally, genetic distance was compared between the HQ Registry and the HQ CBB by region using Non-metric Multi-dimensional Scaling (NMDS).

Results

Because of the small sample size in certain regions, HLA frequency was analyzed for 7 of the 17 regions within the HQ CBB with typings from 11,472 cord blood units. The HLA allele frequencies were previously assessed for the Registry, with 3,806 donors originating from 14 administrative regions. The Hardy-Weinberg equilibrium was rejected at least in relation to one locus in 3 regions (Capitale-Nationale, Montreal, and Laval), which differs from the results obtained from the Registry, in which the equilibrium was rejected only for Montreal. As in the Registry, allele frequencies in the HQ CBB varied by region but had limited overlap with the HQ Registry. Two regions (Chaudière-Appalaches and Laval) demonstrated significant differences in allele frequencies as represented in the HQ Registry versus the HQ CBB.

Discussion

We observed differences in the Quebec population representation between the HQ CBB and the HQ Registry. This probably represents selection bias related to recruitment strategies and inclusion criteria. Importantly, the complementarity of these two stem cell sources could allow for a more diverse donor pool, and this understanding could also guide the recruitment strategies.

Abstract 25 ECTmatch: Optimizing Small-Scale Cord Blood Banking Through HLA Analysis

Introduction

Cord blood (CB) banks have had to rely on large inventories of CB units to try to serve the largest possible proportion of the population, all the while prioritizing collection of non-Caucasian ethnic groups. However, due to the high linkage disequilibrium of HLA genes and the high frequency of several HLA alleles in the population, CB banks contain hundreds of CB units that could be matched to the same patients, making the inventory somewhat redundant from a clinical standpoint.

Objective

ExCellThera developed ECTmatch, an algorithm dedicated to optimizing the selection of CB units based on in-depth HLA analysis in order to maximize the efficiency of the bank to suitably match the largest proportion of subjects within a small pool of donors.

Methods

The performance of ECTmatch was evaluated in a simulation aiming to select 100 CB units from the Héma-Québec CB bank that satisfied an arbitrary minimal cell content criteria of 120 × 10⁷ TNC and 6 × 10⁶ CD34+ cells (n = 2,987). Selection was performed to optimize matching for the Quebec population, with a minimal HLA-match of 5/8 for HLA-A, -B, -C, and -DRB1.

Results

ECTmatch provides a suitably matched donor for 71.5% of the Quebec population, compared with only 45.0% (±2.4%) with random selection. Because patients who require a CB transplant tend to have rarer HLAs, the performance of ECTmatch was evaluated for this specific subset of patients (n = 62). Again, ECTmatch outperformed random selection, by providing a donor for 54.8% of patients, compared with only 29.9% with random selection. Finally, while ECTmatch was developed to optimize CB selection specifically for the Quebec population, it still outperformed random selection for subjects from the other Canadian provinces or the USA.

Discussion

By selecting CB units based on HLA profiles, ECTmatch allows the creation of a highly useful inventory with a very low number of CB units. This approach to small-scale CB banking can be adapted to different population subsets and could be used to select a subset of CB units for pre-release for immediate clinical availability or for the creation of a pre-expanded CB inventory with maximal population coverage.

COVID-19 vaccine coverage and factors associated with vaccine uptake among individuals with a recent experience of homelessness: a population-based analysis from Ontario, Canada

ObjectivesTo describe COVID-19 vaccine coverage (i.e., the estimated percentage of people who have received a vaccine) and determinants of vaccine receipt among individuals with a recent experience of homelessness in Ontario, Canada. ApproachWe conducted a retrospective, population-based cohort study of 23,247 individuals (≥18 years) with a recent experience of homelessness as recorded in routinely collected healthcare databases. Participants were followed from December 14, 2020 to September 30, 2021 for the receipt of a COVID-19 vaccine. Using modified Poisson regression, we identified sociodemographic, healthcare usage, and clinical factors associated with the receipt of one or more doses of a COVID-19 vaccine. ResultsBy September 30, 14,271 (61.4%) of participants with a recent experience of homelessness had received a first dose of a COVID-19 vaccine and 11,082 (47.7%) had received two doses. Over the same period, 86.6% and 81.6% of the total adult population of Ontario had received a first dose and second dose, respectively. In multivariable analysis, factors associated with increased COVID-19 uptake included ≥1 visit to a general practitioner (adjusted Risk Ratio [aRR]:1.37[95% CI 1.31-1.42]), older age (vs. 18-29 years: 50-59 years, aRR:1.18[1.14-1.22]; 60+ years, aRR:1.27[1.22-1.31]), receipt of an influenza vaccine (aRR:1.25[1.23-1.28]), receipt of  ≥1 SARS-CoV-2 test (aRR:1.23[1.20-1.26]) and the presence of chronic health conditions (vs. 0 conditions: 1 condition, aRR:1.05[1.03, 1.08]; 2+ conditions, aRR:1.11[1.08-1.14]). In contrast, living in a smaller metropolitan region (aRR:0.92[0.90-0.94]) or rural location (aRR:0.93[0.90-0.97]) compared to a large metropolitan region was associated with lower uptake. ConclusionsAs of September 30, 2021, COVID-19 vaccine coverage among individuals with a recent experience of homelessness in Ontario was substantially lower than the general adult population of Ontario for a first and second dose. Findings underscore the importance of leveraging organizations that are accessed and trusted by people who experience homelessness for targeted vaccine delivery.

Exploring COVID-19 vaccine uptake, confidence and hesitancy among people experiencing homelessness in Toronto, Canada: protocol for the Ku-gaa-gii pimitizi-win qualitative study

INTRODUCTION

People experiencing homelessness are at high risk for COVID-19 and poor outcomes if infected. Vaccination offers protection against serious illness, and people experiencing homelessness have been prioritised in the vaccine roll-out in Toronto, Canada. Yet, current COVID-19 vaccination rates among people experiencing homelessness are lower than the general population. This study aims to characterise reasons for COVID-19 vaccine uptake and hesitancy among people experiencing homelessness, to identify strategies to overcome hesitancy and provide public health decision-makers with information to improve vaccine confidence and uptake in this priority population.

METHODS AND ANALYSIS

The Ku-gaa-gii pimitizi-win qualitative study (formerly the COVENANT study) will recruit up to 40 participants in Toronto who are identified as experiencing homelessness at the time of recruitment. Semistructured interviews with participants will explore general experiences during the COVID-19 pandemic (eg, loss of housing, social connectedness), perceptions of the COVID-19 vaccine, factors shaping vaccine uptake and strategies for supporting enablers, addressing challenges and building vaccine confidence.

ETHICS AND DISSEMINATION

Approval for this study was granted by Unity Health Toronto Research Ethics Board. Findings will be communicated to groups organising vaccination efforts in shelters, community groups and the City of Toronto to construct more targeted interventions that address reasons for vaccine hesitancy among people experiencing homelessness. Key outputs will include a community report, academic publications, presentations at conferences and a Town Hall that will bring together people with lived expertise of homelessness, shelter staff, leading scholars, community experts and public health partners.

Cancer incidence and stage at diagnosis among people with recent-onset psychotic disorders: A retrospective cohort study using health administrative data from Ontario, Canada

OBJECTIVE

Prior evidence on the relative risk of cancer among people with psychotic disorders is equivocal. The objective of this study was to compare incidence and stage at diagnosis of cancer for people with psychotic disorders relative to the general population.

METHOD

We constructed a retrospective cohort of people with a first diagnosis of non-affective psychotic disorder and a comparison group from the general population using linked health administrative databases in Ontario, Canada. The cohort was followed for incident diagnoses of cancer over a 25-year period. We used Poisson and logistic regression models to compare cancer incidence and stage at diagnosis between people with psychotic disorders and the comparison group, adjusting for confounding factors.

RESULTS

People with psychotic disorders had an 8.6% higher incidence (IRR=1.09, 95%CI=1.05,1.12) of cancer overall relative to the comparison group, with effect modification by sex and substantial variation across cancer sites. People with psychotic disorders also had 23% greater odds (OR=1.23, 95%CI=1.13,1.34) of being diagnosed with more advanced stage cancer relative to the comparison group.

CONCLUSIONS

We found evidence of elevated cancer incidence in people with non-affective psychotic disorders relative to the general population. The higher odds of more advanced stage cancer diagnoses in people with psychotic disorders represents an opportunity to improve patient participation in recommended cancer screening, as well as timely access to services for cancer diagnosis and treatment. Future research should examine confounding effects of lifestyle factors and antipsychotic medications on the risk of developing cancer among people with psychotic disorders. This article is protected by copyright. All rights reserved.

Drug Overdoses During the COVID-19 Pandemic Among Recently Homeless Individuals

AIMS

To examine how weekly rates of emergency department (ED) visits for drug overdoses changed among individuals with a recent history of homelessness (IRHH) and their housed counterparts during the pre-pandemic, peak, and re-opening periods of the first wave of the COVID-19 pandemic, using corresponding weeks in 2019 as a historical control.

DESIGN

Population-based retrospective cohort study conducted between September 30, 2018 and September 26, 2020.

SETTING

Ontario, Canada.

PARTICIPANTS

A total of 38 617 IRHH, 15 022 369 housed individuals, and 186 858 low-income housed individuals matched on age, sex, rurality, and comorbidity burden.

MEASUREMENTS

ED visits for drug overdoses of accidental and undetermined intent.

FINDINGS

Average rates of ED visits for drug overdoses between January and September 2020 were higher among IRHH compared with housed individuals (rate ratio [RR], 148.0; 95% CI, 142.7-153.5) and matched housed individuals (RR, 22.3; 95% CI, 20.7-24.0). ED visits for drug overdoses decreased across all groups by ~20% during the peak period (March 17 to June 16, 2020) compared with corresponding weeks in 2019. During the re-opening period (June 17 to September 26, 2020), rates of ED visits for drug overdoses were significantly higher among IRHH (RR, 1.56; 95% CI, 1.44-1.69), matched housed individuals (RR, 1.25; 95% CI, 1.08-1.46), and housed individuals relative to equivalent weeks in 2019 (RR, 1.07; 95% CI, 1.02-1.11). The relative increase in drug overdose ED visits among IRHH was larger compared with both matched housed individuals (P = 0.01 for interaction between group and year) and housed individuals (P < 0.001) during this period.

CONCLUSIONS

Recently homeless individuals in Ontario, Canada experienced disproportionate increases in ED visits for drug overdoses during the re-opening period of the COVID-19 pandemic compared with housed people.

Factors associated with acute kidney injury among patients with cancer treated with immune checkpoint inhibitor therapy: A population-based study

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Background: Cancer immune checkpoint inhibitor (ICI) therapy may be associated with kidney immune-related adverse events (IRAEs) and other causes of acute kidney injury (AKI). In clinical trials, the frequency of AKI events was uncommon, however, further real-world study is warranted. Methods: We evaluated the proportion of AKI events among patients with advanced cancer (bladder, head and neck, lung, kidney and malignant melanoma) treated with ICI therapy in Ontario, Canada from 2012 - 2018. AKI was defined by a rise in the concentration of serum creatinine as per Kidney Disease: Improving Global Outcomes (KDIGO) criteria. A multivariable regression model was used to identify predictors of AKI while accounting for the competing risk of death. Results: A total of 4,380 patients received ICI therapy. In follow-up, 1,283 (29%) had recorded AKI event (any stage AKI) and 289 (7%) had a severe AKI event (≥ stage 2). Median time to AKI was 6 months (Interquartile Range 2-16 months) and ≤ 1 % of patients received dialysis therapy. Within 30 days of any observed AKI event, 853 (58%) discontinued ICI therapy, 372 (29%) were hospitalized and 266 (21%) died. Mortality was significantly higher among patients who experiencing a severe AKI event (≥ stage 2) as compared to patients with a less severe AKI event (stage 1) or no observed AKI event. Among patients alive at 30 days following an AKI event, 14% received an outpatient corticosteroid or immunosuppressive therapy prescription, 7% had a visit with a nephrologist. Characteristics associated with a higher risk of AKI included female sex, bladder or kidney cancer (reference malignant melanoma), history of hypertension or diabetes, higher Charlson comorbidity score, a baseline estimated glomerular filtration rate less than 30 mL/min/1.73 m2, or outpatient prescription for either a proton pump inhibitor or non-steroidal anti-inflammatory drug. Among patients with an AKI event and treatment discontinuation, re-challenge of ICI therapy was infrequent (16%) with a significant risk of a recurrent AKI event (57%). Conclusions: In a population-based study among patients with cancer receiving ICI therapy, the rate of AKI was common (29%) but severe AKI was less frequent (7%). Rates of ICI discontinuation, hospitalization and death are substantial following an AKI event. Kidney function should be monitored carefully among patients undergoing ICI therapy who have common risk factors for developing renal disease. Nephrology consultation may be optimized among patients who develop a severe AKI event, especially among individuals who are considered for ICI therapy re-challenge.

Hospitalizations During the COVID-19 Pandemic Among Recently Homeless Individuals: a Retrospective Population-Based Matched Cohort Study

BACKGROUND

Hospitalizations fell precipitously among the general population during the COVID-19 pandemic. It remains unclear whether individuals experiencing homelessness experienced similar reductions.

OBJECTIVE

To examine how overall and cause-specific hospitalizations changed among individuals with a recent history of homelessness (IRHH) and their housed counterparts during the first wave of the COVID-19 pandemic, using corresponding weeks in 2019 as a historical control.

DESIGN

Population-based cohort study conducted in Ontario, Canada, between September 30, 2018, and September 26, 2020.

PARTICIPANTS

In total, 38,617 IRHH, 15,022,368 housed individuals, and 186,858 low-income housed individuals matched on age, sex, rurality, and comorbidity burden.

MAIN MEASURES

Primary outcomes included medical-surgical, non-elective (overall and cause-specific), elective surgical, and psychiatric hospital admissions.

KEY RESULTS

Average rates of medical-surgical (rate ratio: 3.8, 95% CI: 3.7-3.8), non-elective (10.3, 95% CI: 10.1-10.4), and psychiatric admissions (128.1, 95% CI: 126.1-130.1) between January and September 2020 were substantially higher among IRHH compared to housed individuals. During the peak period (March 17 to June 16, 2020), rates of medical-surgical (0.47, 95% CI: 0.47-0.47), non-elective (0.80, 95% CI: 0.79-0.80), and psychiatric admissions (0.86, 95% CI: 0.84-0.88) were significantly lower among housed individuals relative to equivalent weeks in 2019. No significant changes were observed among IRHH. During the re-opening period (June 17-September 26, 2020), rates of non-elective hospitalizations for liver disease (1.41, 95% CI: 1.23-1.69), kidney disease (1.29, 95% CI: 1.14-1.47), and trauma (1.19, 95% CI: 1.07-1.32) increased substantially among IRHH but not housed individuals. Distinct hospitalization patterns were observed among IRHH even in comparison with more medically and socially vulnerable matched housed individuals.

CONCLUSIONS

Persistence in overall hospital admissions and increases in non-elective hospitalizations for liver disease, kidney disease, and trauma indicate that the COVID-19 pandemic presented unique challenges for recently homeless individuals. Health systems must better address the needs of this population during public health crises.

Family physician virtual care during COVID-19 in London-Middlesex, Ontario, Canada: a mixed methods exploration

Context: On March 14, 2020, the Ontario, Canada health insurance plan approved COVID-19 physician virtual billing codes; family physicians (FPs) rapidly adopted a new model of care. Virtual care may remain post-pandemic; however, its future should be informed by evidence that considers access and continuity. Objective: 1) to determine FP virtual visit volumes and patient characteristics and 2) to explore FPs' perspectives on virtual visit adoption and implementation. Study Design: Mixed methods: Secondary analysis of health administrative (HA) data and semi-structured qualitative interviews with FPs. Setting or Dataset: London and Middlesex County, Ontario, Canada. HA data through ICES, Ontario entity holding data. Population studied: FPs and their patients. Outcome Measures: Volumes of FP in-person and virtual visits during early pandemic; characteristics of patients receiving care; FPs' perspectives on adopting and delivering virtual care. Results: Overall visit volume dropped by 36% during first wave, recovered to pre-pandemic levels by October 2020. Sharp in-person visit drop of 73% and virtual visit uptake from 0.08% of total visits to 57% within two weeks of March 2020. FPs described this initial drop in volume as patients not seeking care and practices lacking PPE. The move to virtual care was largely to telephone visits. Patient characteristics compared to pre-pandemic, the proportion seeking care were older (46 vs 50 years), more vulnerable (38% vs 41%), and more multimorbidity (33% vs 41%). This was consistent with FP reports that healthier patients stayed away, routine care deferred, sicker patients needed to be seen. FPs believed most vulnerable patients had access to care but cautioned highly vulnerable such as those homeless did not have cell phone access or a safe place to receive calls. Rural FPs reported access issues because of lack of high-speed internet. FPs attributed success of virtual care to the continuity in relationships they had with patients that were established in person pre-pandemic. Conclusions: FPs moved rapidly to virtual care. FP offices remained open despite PPE concerns but overall volumes dropped initially. Vulnerable and sicker patients received care but FPs expressed concern for highly vulnerable and rural residents. FPs believed they could offer patient-centred care over the phone but indicated the importance of maintaining in-person care to build relationships.

COVID-19 vaccine coverage and factors associated with vaccine uptake among 23 247 adults with a recent history of homelessness in Ontario, Canada: a population-based cohort study

BACKGROUND

People experiencing homelessness face a high risk of SARS-CoV-2 infection and transmission, as well as health complications and death due to COVID-19. Despite being prioritised for receiving the COVID-19 vaccine in many regions, little data are available on vaccine uptake in this vulnerable population. Using population-based health-care administrative data from Ontario, Canada-a region with a universal, publicly funded health system-we aimed to describe COVID-19 vaccine coverage (ie, the estimated percentage of people who have received a vaccine) and determinants of vaccine receipt among individuals with a recent history of homelessness.

METHODS

We conducted a retrospective, population-based cohort study of adults (aged ≥18 years) with a recent experience of homelessness, inadequate housing, or shelter use as recorded in routinely collected health-care databases between June 14, 2020, and June 14, 2021 (a period within 6 months of Dec 14, 2020, when COVID-19 vaccine administration was initiated in Ontario). Participants were followed up from Dec 14, 2020, to Sept 30, 2021, for the receipt of one or two doses of a COVID-19 vaccine using the province's real-time centralised vaccine information system. We described COVID-19 vaccine coverage overall and within predefined subgroups. Using modified Poisson regression, we further identified sociodemographic factors, health-care usage, and clinical factors associated with receipt of at least one dose of a COVID-19 vaccine.

FINDINGS

23 247 individuals with a recent history of homelessness were included in this study. Participants were predominantly male (14 752 [63·5%] of 23 247); nearly half were younger than 40 years (11 521 [49·6%]) and lived in large metropolitan regions (12 123 [52·2%]); and the majority (18 226 [78·4%]) visited a general practitioner for an in-person consultation during the observation period. By Sept 30, 2021, 14 271 (61·4%; 95% CI 60·8-62·0) individuals with a recent history of homelessness had received at least one dose of a COVID-19 vaccine and 11 082 (47·7%; 47·0-48·3) had received two doses; in comparison, over the same period, 86·6% of adults in the total Ontario population had received a first dose and 81·6% had received a second dose. In multivariable analysis, factors positively associated with COVID-19 uptake were one or more outpatient visits to a general practitioner (adjusted risk ratio [aRR] 1·37 [95% CI 1·31-1·42]), older age (50-59 years vs 18-29 years: 1·18 [1·14-1·22], ≥60 years vs 18-29 years: 1·27 [1·22-1·31]), receipt of an influenza vaccine in either of the two previous influenza seasons (1·25 [1·23-1·28]), being identified as homeless via a visit to a community health centre versus exclusively a hospital-based encounter (1·13 [1·10-1·15]), receipt of one or more SARS-CoV-2 tests between March 1, 2020, and Sept 30, 2021 (1·23 [1·20-1·26]), and the presence of chronic health conditions (one condition: 1·05 [1·03-1·08]; two or more conditions: 1·11 [1·08-1·14]). By contrast, living in a smaller metropolitan region (aRR 0·92 [95% CI 0·90-0·94]) or rural location (0·93 [0·90-0·97]) versus large metropolitan regions were associated with lower uptake.

INTERPRETATION

In Ontario, COVID-19 vaccine coverage among adults with a recent history of homelessness has lagged and, as of Sept 30, 2021, was 25 percentage points lower than that of the general adult population in Ontario for a first dose and 34 percentage points lower for a second dose. With high usage of outpatient health services among individuals with a recent history of homelessness, better utilisation of outpatient primary care structures might offer an opportunity to increase vaccine coverage in this population. Our findings underscore the importance of leveraging existing health and service organisations that are accessed and trusted by people who experience homelessness for targeted vaccine delivery.

FUNDING

The Public Health Agency of Canada.

TRANSLATION

For the French translation of the abstract see Supplementary Materials section.

Association between Pet Ownership and Mental Health and Well-Being of Canadians Assessed in a Cross-Sectional Study during the COVID-19 Pandemic

The objective of this cross-sectional study was to assess the association between pet ownership and quality of life (QoL), loneliness, anxiety, stress, overall health, and mental health of Canadians during the COVID-19 pandemic using a One Health perspective. An online bilingual survey was completed by 1500 Canadians in April-May 2021. Socio-demographics, health, QoL, stress and anxiety, loneliness, social support, pet ownership, and attitude towards pets data were collected. Crude and adjusted associations between pet ownership and mental health and well-being indicators were estimated. The 1500 participants were from all provinces and territories, half were women; half of the participants were pet owners by design. The crude association estimates showed that pet owners had poorer QoL, overall health, and mental health than non-pet owners, and were lonelier, more stressed, and more anxious than non-pet owners. Adjusted estimates showed that these associations disappeared with the inclusion of the confounders (socio-economic, demographic, health, and pet-related variables). Our results suggest that there was no association between pet ownership and the mental health and well-being indicators measured in the present study.

Healthcare professionals' longitudinal perceptions of group phenomena as determinants of self-assessed learning in organizational communities of practice

BACKGROUND

Given the importance of continuous learning as a response to the increasing complexity of health care practice, there is a need to better understand what makes communities of practice in health effective at fostering learning. Despite the conceptual stance that communities of practice facilitate individual learning, the scientific literature does not offer much evidence for this. Known factors associated with the effectiveness of communities of practice - such as collaboration, psychological safety within the community, and commitment to the community - have been studied in cross-sectional qualitative designs. However, no studies to date have used a quantitative predictive design. The objective of this study is to assess how members of a community of practice perceive interactions among themselves and determine the extent to which these interactions predict self-assessed learning over time.

METHODS

Data was collected using validated questionnaires from six communities of practice (N = 83) in four waves of measures over the course of 36 months and was analysed by means of General Estimating Equations. This allowed to build a longitudinal model of the associations between perceptions of collaboration, psychological safety within the community, commitment to the community and self-assessed learning over time.

RESULTS

Perception of collaboration in the community of practice, a personal sense of psychological safety and a commitment to the community of practice are predictors longitudinally associated with self-assessed learning.

CONCLUSIONS

In terms of theory, conceptual links can be made between intensity of collaboration and learning over time in the context of a community of practice. Recent work on psychological safety suggests that it is still unclear whether psychological safety acts as a direct enhancer of learning or as a remover of barriers to learning. This study's longitudinal results suggest that psychological safety may enhance how and to what extent professionals feel they learn over time. Commitment towards the community of practice is a strong predictor of learning over time, which hints at differential effects of affective, normative and continuance commitment. Communities of practice can therefore apply these findings by making collaboration, psychological safety, commitment and learning regular reflexive topics of discussion.

Utility, Limitations and Opportunities for Using Linked Health Administrative Data to Study Homelessness in Ontario

Homelessness is a significant social issue within Canada but is difficult to quantify at the population level. In this paper, we discuss the development and use of a case ascertainment algorithm that identifies people experiencing homelessness through health administrative data. We highlight the appropriateness of various uses of this method given its key strengths and limitations. Finally, we discuss plans to improve this methodology and broaden its use through the addition of linkable administrative data from non-health sectors, such as emergency shelters and social services organizations.

Fracture profiles of a 4-year cohort of 266,324 first incident upper extremity fractures from population health data in Ontario

Background

Understanding the profiles of different upper extremity fractures, particularly those presenting as a 1st incident can inform prevention and management strategies. The purpose of this population-level study was to describe first incident fractures of the upper extremity in terms of fracture characteristics and demographics.

Methods

Cases with a first adult upper extremity (UE) fracture from the years 2013 to 2017 were extracted from administrative data in Ontario. Fracture locations (ICD-10 codes) and associated characteristics (open/closed, associated hospitalization within 1-day, associated nerve, or tendon injury) were described by fracture type, age category and sex. Standardized mean differences of at least 10% (clinical significance) and statistical significance (p < 0.01) in ANOVA were used to identify group differences (age/sex).

Results

We identified 266,324 first incident UE fractures occurring over 4 years. The most commonly affected regions were the hand (93 K), wrist/forearm(80 K), shoulder (48 K) or elbow (35 K). The highest number of specific fractures were: distal radius (DRF, 47.4 K), metacarpal (30.4 K), phalangeal (29.9 K), distal phalangeal (24.4 K), proximal humerus (PHF, 21.7 K), clavicle (15.1 K), radial head (13.9 K), and scaphoid fractures (13.2 K). The most prevalent multiple fractures included: multiple radius and ulna fractures (11.8 K), fractures occurring in multiple regions of the upper extremity (8.7 K), or multiple regions in the forearm (8.4 K). Tendon (0.6% overall; 8.2% in multiple finger fractures) or nerve injuries were rarely reported (0.3% overall, 1.5% in distal humerus). Fractures were reported as being open in 4.7% of cases, most commonly for distal phalanx (23%). A similar proportion of females (51.5%) and males were present in this fracture cohort, but there were highly variant age-sex profiles across fracture subtypes. Fractures most common in 18–40-year-old males included metacarpal and finger fractures. Fractures common in older females were: DRF, PHF and radial head, which exhibited a dramatic increase in the over-50 age group.

Conclusions

UE fracture profiles vary widely by fracture type. Fracture specific prevention and management should consider fracture profiles that are highly variable according to age and sex.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12891-021-04849-7.

Does COVID-19 infection change the need for future surgical interventions? An exploratory analysis

Background: It is unknown whether recovery from coronavirus disease 2019 (COVID-19) infection leads to an increased need for common surgical procedures. Our objective was to conduct an exploratory analysis of surgical procedures performed after a documented COVID-19 infection.  Methods: We conducted a retrospective cohort study using routinely collected data from the province of Ontario, Canada. We identified individuals with a positive COVID-19 test between February 1 2020 and May 31 2020, and matched them 1:2 with individuals who had a negative COVID-19 test during the same period. We used physician billing codes to identify the ten most frequent surgical procedures in the COVID-19 cohort. An at-risk period 30 days after the first positive COVID-19 swab (or matched index date in the control group) until November 30 2020 was used. Cox proportional hazard models (adjusted for important baseline differences) are reported with hazard ratios (HR) and 95% confidence intervals.   Results: After exclusions and matching, we had 19,143 people in the COVID-19 cohort, and 38,286 people in the control cohort. The top ten surgical procedures were hand/wrist fracture fixation, cesarean-section, ureteral stent placement, cholecystectomy, treatment of an upper tract urinary stone, hysterectomy, femur fracture repair, hip replacement, transurethral prostatectomy, and appendectomy. There was a significantly reduced hazard of requiring upper tract renal stone surgery (adjusted hazard ratio [aHR] 0.50, 95% confidence interval [CI] 0.29-0.87) or ureteral stent placement (aHR 0.54, 95%CI 0.36-0.82), or undergoing a cholecystectomy (aHR 0.43, 95%CI 0.26-0.71) among those with a prior positive COVID-19 test.   Conclusions: After a COVID-19 infection there is not an increased risk of needing several common surgical procedures. There appears to be a reduced risk of renal stone disease treatment and ureteral stent placement, and a reduced risk of cholecystectomy, however understanding the reasons for this will require further study.

Survival and development of health conditions after iron depletion therapy in C282Y-linked hemochromatosis patients

BACKGROUND

We report long-term survival and development of selected health conditions in Ontario-based referred and screened C282Y homozygotes for hemochromatosis treated by phlebotomy compared with an untreated control group known to be without HFE mutations.

METHODS

Patient characteristics and outcomes (all-cause mortality, liver cancer, diabetes, cirrhosis, hip or knee joint replacement, and osteoarthritis) were ascertained using a linked health administrative database held at ICES. Outcomes were assessed between groups without the outcome at baseline using Cox proportional hazards regression adjusted for age and sex. All C282Y homozygotes with elevated serum ferritin were treated by phlebotomy to reach serum ferritin of 50 µg/L. Our cohort included 527 C282Y homozygotes (311 men, 216 women, mean age 48 years) and 12,879 control participants (5,667 men and 7,212 women).

RESULTS

C282Y homozygotes had an increased risk of all-cause mortality (aHR 1.44 [1.19-1.75], p <0.001); hepatocellular carcinoma (aHR 8.30 [3.97-17.34], p <0.001); hip or knee joint replacement (aHR 3.06 [2.46-3.81], p <0.001); osteoarthritis (aHR 1.72 [1.47-2.01], p <0.001); and cirrhosis (aHR 3.87 [3.05-4.92], p <0.001). C282Y homozygotes did not have an increased risk for diagnosis of diabetes) (aHR 0.84 [0.67-1.07], p = 0.16) during follow-up (median 17.7 y).

CONCLUSIONS

C282Y homozygotes experience higher death and complication rates than individuals without HFE mutations, despite treatment by phlebotomy. Diabetes did not increase after phlebotomy therapy.

The association between endocrine therapy use and osteoporotic fracture among post-menopausal women treated for early-stage breast cancer in Ontario, Canada

Background

The use of endocrine therapy for early-stage breast cancer, particularly aromatase inhibitor therapy has been associated with an increased risk of osteoporosis and fracture in clinical trials. We sought to validate this observation in real-world practice.

Methods

We used health administrative data collected from post-menopausal women (aged ≥66 years) who were diagnosed with breast cancer and started on adjuvant endocrine therapy from 2005 to 2012. Patients were classified by use of either an aromatase inhibitor or tamoxifen and followed until 2017 for a new diagnosis of an osteoporotic fracture. A multivariable analysis using a Cox proportional hazards model was adjusting for age, medical co-morbidities, medication use and duration of endocrine therapy.

Results

We identified 12,077 patients of whom 73% were treated with an aromatase inhibitor as compared to 27% with tamoxifen. Our multivariable analysis did not demonstrate any significant difference in the rate of osteoporotic fracture between patients treated with an aromatase inhibitor when compared with tamoxifen [Hazard ratio (HR) = 1.09; 95% confidence interval (CI) = 0.96–1.23, p-value = 0.18]. The 5-year rate of osteoporotic fracture for patients treated with either an aromatase inhibitor or tamoxifen was 7.5% and 6.9%, respectively. A completed sensitivity analysis did observe a decreased risk of fracture associated with tamoxifen usage over time.

Conclusion

We could not detect a significant difference in the rate of osteoporotic fracture among patients treated with an aromatase inhibitor versus tamoxifen. Nonetheless, the risk with tamoxifen was numerically lower and significantly decreased when accounting for total duration of endocrine therapy.

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Our real-world study investigated the osteoporotic fracture risk among early-stage post-menopausal breast cancer patients.

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No significant difference in fracture rates was observed among patients treated with aromatase inhibitors versus tamoxifen.

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The risk of osteoporotic fracture decreased with tamoxifen usage over time.

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Bone health should be carefully monitored and optimized among breast cancer patients recieving endocrine therapy.

Neighbourhood material deprivation and severe maternal morbidity: a population-based cohort study in Ontario, Canada

OBJECTIVES

Rates of age-associated severe maternal morbidity (SMM) have increased in Canada, and an association with neighbourhood income is well established. Our aim was to examine SMM trends according to neighbourhood material deprivation quintile, and to assess whether neighbourhood deprivation effects are moderated by maternal age.

DESIGN, SETTING AND PARTICIPANTS

A population-based retrospective cohort study using linked administrative databases in Ontario, Canada. We included primiparous women with a live birth or stillbirth at ≥20 weeks' gestational age.

PRIMARY OUTCOME

SMM from pregnancy onset to 42 days postpartum. We calculated SMM rate differences (RD) and rate ratios (RR) by neighbourhood material deprivation quintile for each of four 4-year cohorts from 1 April 2002 to 31 March 2018. Log-binomial multivariable regression adjusted for maternal age, demographic and pregnancy-related variables.

RESULTS

There were 1 048 845 primiparous births during the study period. The overall rate of SMM was 18.0 per 1000 births. SMM rates were elevated for women living in areas with high material deprivation. In the final 4-year cohort, the RD between women living in high vs low deprivation neighbourhoods was 3.91 SMM cases per 1000 births (95% CI: 2.12 to 5.70). This was higher than the difference observed during the first 4-year cohort (RD 2.09, 95% CI: 0.62 to 3.56). SMM remained associated with neighbourhood material deprivation following multivariable adjustment in the pooled sample (RR 1.16, 95% CI: 1.11 to 1.21). There was no evidence of interaction with maternal age.

CONCLUSION

SMM rate increases were more pronounced for primiparous women living in neighbourhoods with high material deprivation compared with those living in low deprivation areas. This raises concerns of a widening social gap in maternal health disparities and highlights an opportunity to focus risk reduction efforts toward disadvantaged women during pregnancy and postpartum.

Microglia-neuron interaction at nodes of Ranvier depends on neuronal activity through potassium release and contributes to remyelination

Microglia, the resident immune cells of the central nervous system, are key players in healthy brain homeostasis and plasticity. In neurological diseases, such as Multiple Sclerosis, activated microglia either promote tissue damage or favor neuroprotection and myelin regeneration. The mechanisms for microglia-neuron communication remain largely unkown. Here, we identify nodes of Ranvier as a direct site of interaction between microglia and axons, in both mouse and human tissues. Using dynamic imaging, we highlight the preferential interaction of microglial processes with nodes of Ranvier along myelinated fibers. We show that microglia-node interaction is modulated by neuronal activity and associated potassium release, with THIK-1 ensuring their microglial read-out. Altered axonal K⁺ flux following demyelination impairs the switch towards a pro-regenerative microglia phenotype and decreases remyelination rate. Taken together, these findings identify the node of Ranvier as a major site for microglia-neuron interaction, that may participate in microglia-neuron communication mediating pro-remyelinating effect of microglia after myelin injury.

Microglia are important for brain homeostasis and plasticity. The mechanisms underlying microglia-neuron interactions are still unclear. Here, the authors show that microglia preferentially interact with the nodes of Ranvier along axons. This interaction is modulated by neuronal activity and contributes to remyelination in mice.

Uptake of immunotherapy in patients with advanced cancer: A population-based study using health administrative data from Ontario, Canada

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Background: The introduction of immunotherapy (IO) in the treatment of patients with cancer has significantly improved clinical outcomes. Herein we report on IO uptake in Ontario, Canada, a publicly funded healthcare system. Methods: We conducted a retrospective cohort study using provincial health administrative data to: 1) assess IO uptake in adult patients with advanced melanoma, bladder, lung, head and neck (HN) and kidney cancers; and 2) identify predictors of IO usage between 2011 (pre-IO funding) and 2019. The datasets were linked using unique encoded identifiers and analyzed at ICES. IO uptake was captured between cancer diagnosis and last follow up and reported as a proportion of the entire cohort and by tumor site and drug type. A competing risk Fine and Gray regression model with death as competing risk was used to identify factors associated with IO use. Results: Among 59,510 patients with one of the five advanced cancers of interest, 7,660 (12.9%) received IO. Details of IO uptake are summarized in Table. IO uptake increased yearly from 2011 (2.7%) to 2019 (34.0%). Uptake was highest in melanoma (48.2%) and lowest in HN cancer (5.8%). The most commonly used drugs used were pembrolizumab (41.1%) and nivolumab (40.5%). In adjusted analysis, predictors of lower IO uptake included older age (hazard ratio (HR) 0.953, 95%CI 0.934-0.972 with every additional 10 years), female sex (HR 0.859, 95%CI 0.819-0.9), lower income quintile (HR 0.893, 95%CI 0.83-0.96), history of hospital admission (HR 0.768, 95%CI 0.734-0.805), female oncologist (HR 0.942, 95%CI 0.892-0.995), and de novo stage 4 cancer (HR 0.918, 95%CI 0.873-0.966). Predictors of higher IO uptake were low Charlson score (HR 1.118, 95%CI 1.01-1.236) and previous radiation therapy (HR 1.438, 95%CI 1.367-1.512). IO uptake was heterogeneous across cancer centres levels (1 to 4) and regions. Conclusions: While the use of IO for advanced cancer has steadily increased over time, uptake is associated with patient and physician characteristics, as well as system level factors. This variation suggests potential inequity in access to these potentially life-prolonging drugs and should be further investigated and addressed.[Table: see text]

Is coronavirus disease 2019 associated with indicators of long-term bladder dysfunction?

Objective

Early reports have suggested that coronavirus disease 2019 (COVID‐19) can present with significant urinary frequency and nocturia, and that these symptoms correlate with markers of inflammation in the urine. We evaluated surrogate markers of chronic urinary symptoms to determine if they were more frequent after COVID‐19 infection.

Methods

Routinely collected data from the province of Ontario was used to conduct a matched, retrospective cohort study. We identified patients 66 years of age or older who had a positive COVID‐19 test between February and May 2020 and survived at least 2 months after their diagnosis. We matched them to two similar patients who did not have a positive COVID‐19 test during the same time period. We measured the frequency of urology consultation, cystoscopy, and new prescriptions for overactive bladder medications during a subsequent 3‐month period. Proportional hazard models were adjusted for any baseline differences between the groups.

Results

We matched 5617 patients with COVID‐19 to 11,225 people who did not have COVID‐19. The groups were similar, aside from a higher proportion of patients having hypertension and diabetes in the CoVID‐19 cohort. There was no significantly increased hazard of new receipt of overactive bladder medication (hazards ratio [HR]: 1.04, p = 0.88), urology consultation (HR: 1.40, p = 0.10), or cystoscopy (HR: 1.14, p = 0.50) among patients who had COVID‐19, compared to the matched cohort.

Conclusion

Surrogate markers of potential bladder dysfunction were not significantly increased in the 2–5 months after COVID‐19 infection.

The requirement for surgery and subsequent 30-day mortality in patients with COVID-19

The ongoing COVID-19 pandemic has had profound effects on the provision of surgical care. The potential perioperative mortality associated with surgical procedures in patients with COVID-19 has been estimated at 20%, but the data come from jurisdictions that experienced very high surges of COVID-19 patients. A rapid assessment of the types of surgical care for patients with COVID-19 in Ontario was carried out using administrative data, and we found that during the initial wave in the spring of 2020, surgical interventions were required in 0.6% of patients with COVID-19, and mortality was higher (20%) in patients who underwent surgery in the 2 weeks before or after a positive nasopharygeal swab than in those who had surgery more than 2 weeks after COVID-19 was diagnosed.

Were Snowbirds Disproportionally Impacted by COVID-19? An Ontario Analysis

Early in the first wave of the COVID-19 pandemic, many older adult Canadians who routinely spend the winter months in warmer regions (colloquially known as "snowbirds") returned to Canada. While numerous infections were attributed to travel-related exposure at that time, little is known about the impact of COVID-19 on returning snowbirds. This population-based analysis from Ontario suggests that snowbirds were not disproportionately impacted by the pandemic. However, as older adults, they remain at high risk of complications once infected. These findings underscore the need for continued caution in this older adult population.

Testing, infection and complication rates of COVID-19 among people with a recent history of homelessness in Ontario, Canada: a retrospective cohort study

BACKGROUND

People with a recent history of homelessness are believed to be at high risk of infection with severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) and, when infected, complications of coronavirus disease 2019 (COVID-19). We describe and compare testing for SARS-CoV-2, test positivity and hospital admission, receipt of intensive care and mortality rates related to COVID-19 for people with a recent history of homelessness versus community-dwelling people as of July 31, 2020.

METHODS

We conducted a population-based retrospective cohort study in Ontario, Canada, between Jan. 23 and July 31, 2020, using linked health administrative data among people who either had a recent history of homelessness or were dwelling in the community. People were included if they were eligible for provincial health care coverage and not living in an institutionalized facility on Jan. 23, 2020. We examined testing for SARS-CoV-2, test positivity and complication outcomes of COVID-19 (hospital admission, admission to intensive care and death) within 21 days of a positive test result. Extended multivariable Cox proportional hazard models were used to estimate adjusted hazard ratios (HRs) in 3 time periods: preshutdown (Jan. 23-Mar. 13), peak (Mar. 14-June 16) and reopening (June 17-July 31).

RESULTS

People with a recent history of homelessness (n = 29 407) were more likely to be tested for SARS-CoV-2 in all 3 periods compared with community-dwelling people (n = 14 494 301) (preshutdown adjusted HR 1.61, 95% confidence interval [CI] 1.22-2.11; peak adjusted HR 2.95, 95% CI 2.88-3.03; reopening adjusted HR 1.45, 95% CI 1.39-1.51). They were also more likely to have a positive test result (peak adjusted HR 3.66, 95% CI 3.22-4.16; reopening adjusted HR 1.76, 95% CI 1.15-2.71). In the peak period, people with a recent history of homelessness were over 20 times more likely to be admitted to hospital for COVID-19 (adjusted HR 20.35, 95% CI 16.23-25.53), over 10 times more likely to require intensive care for COVID-19 (adjusted HR 10.20, 95% CI 5.81-17.93) and over 5 times more likely to die within 21 days of their first positive test result (adjusted HR 5.73, 95% CI 3.01-10.91).

INTERPRETATION

In Ontario, people with a recent history of homelessness were significantly more likely to be tested for SARS-CoV-2, to have a positive test result, to be admitted to hospital for COVID-19, to receive intensive care for COVID-19 and to die of COVID-19 compared with community-dwelling people. People with a recent history of homelessness should continue to be considered particularly vulnerable to SARS-CoV-2 infection and its complications.

Epilepsy risk among survivors of intensive care unit hospitalization for sepsis

OBJECTIVE

To determine whether survivors of intensive care unit (ICU) hospitalizations with sepsis experience higher epilepsy risk than survivors of ICU hospitalizations without sepsis, and to identify sepsis survivors at highest risk.

METHODS

We used linked, administrative health care databases to conduct a population-based, retrospective matched cohort study of adult Ontario residents discharged from an ICU between January 1, 2010, and December 31, 2015, identified using the Discharge Abstract Database. We used propensity scores to match patients who experienced sepsis during their index ICU hospitalization with up to 4 patients who did not experience sepsis. We applied marginal Cox proportional hazards regression to estimate the risk of epilepsy within 2 years following the index ICU hospitalization. Among sepsis survivors, Cox proportional hazards regression was used to identify factors associated with epilepsy.

RESULTS

A total of 143,892 patients were included, 32,252 (22.4%) of whom were exposed. Sepsis survivors were at significantly higher epilepsy risk (hazard ratio [HR] 1.44, 95% confidence interval [CI] 1.15-1.80). The risk of epilepsy marginally decreased with increasing age (HR 0.97, 95% CI 0.96-0.99); patients with chronic kidney disease (HR 2.25, 95% CI 1.48-3.43) were at highest risk.

CONCLUSIONS

In this real-world analysis, sepsis survivors, particularly those who are younger and have chronic kidney disease, are at significantly higher epilepsy risk. These findings indicate that sepsis may be an unrecognized epilepsy risk factor.