The Living Kidney Donor Safety Study: Protocol of a Prospective Cohort Study

Background

Living kidney donation is considered generally safe in healthy individuals; however, there is a need to better understand the long-term effects of donation on blood pressure and kidney function.

Objectives

To determine the risk of hypertension in healthy, normotensive adults who donate a kidney compared with healthy, normotensive non-donors with similar indicators of baseline health. We will also compare the 2 groups on the rate of decline in kidney function, the risk of albuminuria, and changes in health-related quality of life.

Design Participants and Setting

Prospective cohort study of 1042 living kidney donors recruited before surgery from 17 transplant centers (12 in Canada and 5 in Australia) between 2004 and 2014. Non-donor participants (n = 396) included relatives or friends of the donor, or donor candidates who were ineligible to donate due to blood group or cross-match incompatibility. Follow-up will continue until 2021, and the main analysis will be performed in 2022. The anticipated median (25th, 75th percentile, maximum) follow-up time after donation is 7 years (6, 8, 15).

Measurements

Donors and non-donors completed the same schedule of measurements at baseline and follow-up (non-donors were assigned a simulated nephrectomy date). Annual measurements were obtained for blood pressure, estimated glomerular filtration rate (eGFR), albuminuria, patient-reported health-related quality of life, and general health.

Outcomes

Incident hypertension (a systolic/diastolic blood pressure ≥ 140/90 mm Hg or receipt of anti-hypertensive medication) will be adjudicated by a physician blinded to the participant's donation status. We will assess the rate of change in eGFR starting from 12 months after the nephrectomy date and the proportion who develop an albumin-to-creatinine ratio ≥3 mg/mmol (≥30 mg/g) in follow-up. Health-related quality of life will be assessed using the 36-item RAND health survey and the Beck Anxiety and Depression inventories.

Limitations

Donation-attributable hypertension may not manifest until decades after donation.

Conclusion

This prospective cohort study will estimate the attributable risk of hypertension and other health outcomes after living kidney donation.

Perioperative Complications During Living Donor Nephrectomy: Results From a Multicenter Cohort Study

BACKGROUND

While living kidney donation is considered safe in healthy individuals, perioperative complications can occur due to several factors.

OBJECTIVE

We explored associations between the incidence of perioperative complications and donor characteristics, surgical technique, and surgeon's experience in a large contemporary cohort of living kidney donors.

DESIGN

Living kidney donors enrolled prospectively in a multicenter cohort study with some data collected retrospectively after enrollment was complete (eg, surgeon characteristics).

SETTING

Living kidney donor centers in Canada (n = 12) and Australia (n = 5).

PATIENTS

Living kidney donors who donated between 2004 and 2014 and the surgeons who performed the living kidney donor nephrectomies.

MEASUREMENTS

Operative and hospital discharge medical notes were collected prospectively, with data on perioperative (intraoperative and postoperative) information abstracted from notes after enrollment was complete. Complications were graded using the Clavien-Dindo system and further classified into minor and major. In 2016, surgeons who performed the nephrectomies were invited to fill an online survey on their training and experience.

METHODS

Multivariable logistic regression models with generalized estimating equations were used to compare perioperative complication rates between different groups of donors. The effect of surgeon characteristics on the complication rate was explored using a similar approach. Poisson regression was used to test rates of overall perioperative complications between high- and low-volume centers.

RESULTS

Of the 1421 living kidney donor candidates, 1042 individuals proceeded with donation, where 134 (13% [95% confidence interval (CI): 11%-15%]) experienced 142 perioperative complications (55 intraoperative; 87 postoperative). The most common intraoperative complication was organ injury and the most common postoperative complication was ileus. No donors died in the perioperative period. Most complications were minor (90% of 142 complications [95% CI: 86%-96%]); however, 12 donors (1% of 1042 [95% CI: 1%-2%]) experienced a major complication. No statistically significant differences were observed between donor groups and the rate of complications. A total of 43 of 48 eligible surgeons (90%) completed the online survey. Perioperative complication rates did not vary significantly by surgeon characteristics or by high- versus low-volume centers.

LIMITATIONS

Operative and discharge reporting is not standardized and varies among surgeons. It is possible that some complications were missed. The online survey for surgeons was completed retrospectively, was based on self-report, and has not been validated. We had adequate statistical power only to detect large effects for factors associated with a higher risk of perioperative complications.

CONCLUSIONS

This study confirms the safety of living kidney donation as evidenced by the low rate of major perioperative complications. We did not identify any donor or surgeon characteristics associated with a higher risk of perioperative complications.

TRIAL REGISTRATIONS

NCT00319579: A Prospective Study of Living Kidney Donation (https://clinicaltrials.gov/ct2/show/NCT00319579)NCT00936078: Living Kidney Donor Study (https://clinicaltrials.gov/ct2/show/NCT00936078).

Duration of Living Kidney Transplant Donor Evaluations: Findings From 2 Multicenter Cohort Studies

BACKGROUND

A prolonged living kidney donor evaluation may result in worse outcomes for transplant recipients. Better knowledge of the duration of this process may help inform future donors and identify opportunities for improvement.

STUDY DESIGN

1 prospective and 1 retrospective cohort study.

SETTING & PARTICIPANTS

At 16 Canadian and Australian transplantation centers (prospective cohort) and 5 Ontario transplantation centers (retrospective cohort), we assessed the duration of living kidney donor evaluation and explored donor, recipient, and transplantation factors associated with longer evaluation times. Data were obtained from 2 sources: donor medical records using chart abstraction and health care administrative databases.

PREDICTORS

Donor and recipient demographics, direct versus paired donation, center-level variables.

OUTCOMES

Duration of living donor evaluation.

RESULTS

The median total duration of transplantation evaluation (time from when the candidate started the evaluation until donation) was 10.3 (IQR, 6.5-16.7) months. The median duration from evaluation start until approval to donate was 7.9 (IQR, 4.6-14.1) months, and from approval until donation was 0.7 (IQR, 0.3-2.4) months, respectively. The median time between the first and last consultation among donors who completed a nephrology, surgery, and psychosocial assessment in the prospective cohort was 3.0 (IQR, 1.0-6.3) months, and between computed tomography angiography and donation was 4.8 (IQR, 2.6-9.2) months. After adjustment, the total duration of transplantation evaluation was longer if the donor participated in paired donation (6.6 [95% CI, 1.6-9.7] months) and if the recipient was referred later relative to the donor's evaluation start date (0.9 [95% CI, 0.8-1.0] months [per month of delayed referral]). Results depended on whether the recipient was receiving dialysis.

LIMITATIONS

Living donor candidates who did not donate were not included and proxy measures were used for some dates in the donor evaluation process.

CONCLUSIONS

The duration of kidney transplant donor evaluation is variable and can be lengthy. Better understanding of the reasons for a prolonged evaluation may inform quality improvement initiatives to reduce unnecessary delays.

Gestational hypertension and preeclampsia in living kidney donors

BACKGROUND

Young women wishing to become living kidney donors frequently ask whether nephrectomy will affect their future pregnancies.

METHODS

We conducted a retrospective cohort study of living kidney donors involving 85 women (131 pregnancies after cohort entry) who were matched in a 1:6 ratio with 510 healthy nondonors from the general population (788 pregnancies after cohort entry). Kidney donations occurred between 1992 and 2009 in Ontario, Canada, with follow-up through linked health care databases until March 2013. Donors and nondonors were matched with respect to age, year of cohort entry, residency (urban or rural), income, number of pregnancies before cohort entry, and the time to the first pregnancy after cohort entry. The primary outcome was a hospital diagnosis of gestational hypertension or preeclampsia. Secondary outcomes were each component of the primary outcome examined separately and other maternal and fetal outcomes.

RESULTS

Gestational hypertension or preeclampsia was more common among living kidney donors than among nondonors (occurring in 15 of 131 pregnancies [11%] vs. 38 of 788 pregnancies [5%]; odds ratio for donors, 2.4; 95% confidence interval, 1.2 to 5.0; P=0.01). Each component of the primary outcome was also more common among donors (odds ratio, 2.5 for gestational hypertension and 2.4 for preeclampsia). There were no significant differences between donors and nondonors with respect to rates of preterm birth (8% and 7%, respectively) or low birth weight (6% and 4%, respectively). There were no reports of maternal death, stillbirth, or neonatal death among the donors. Most women had uncomplicated pregnancies after donation.

CONCLUSIONS

Gestational hypertension or preeclampsia was more likely to be diagnosed in kidney donors than in matched nondonors with similar indicators of baseline health. (Funded by the Canadian Institutes of Health Research and others.).

Accuracy of portrayal by standardized patients: results from four OSCE stations conducted for high stakes examinations

BACKGROUND

The reliability in Objective Structured Clinical Exams (OSCEs) is based on variance introduced due to examiners, stations, items, standardized patients (SP), and the interaction of one or more of these items with the candidates. The impact of SPs on the reliability has not been well studied. Accordingly, the main purpose of the present study was to assess the accuracy of portrayal by standardized patients.

METHODS

Four stations from a ten station high-stakes OSCE were selected for video recording. Due to the large number of candidates to be evaluated, the OSCE was administered using four assessment tracks. Four SPs were trained for each case (n = 16). Two physician assessors were trained to assess the accuracy of SP portrayal using a station-specific instrument based on the station guidelines. For the items with disagreement a third physician was asked to review and the mode was used for analysis. Each instrument included case-specific items on verbal and physical portrayal using a 3-point rating scale ("yes", "yes, but" and "not done"). The physician assessors also scored each SP on their overall performance based on a 5-item anchored global rating scale ("very poor", "poor", "ok", "good", and "very good"). SPs at location 1 were trained by one trainer and SPs at location 2 had another trainer. All SPs were employed in a high-stakes OSCE for at least the second time.

RESULTS

The reliability of rating scores ranged from Cronbach's alpha of .40 to .74. Verbal portrayal by SPs did not significantly differ for most items; however, the facial expressions of the SPs differed significantly (p < .05). An emergency management station that depended heavily on SPs physical presentation and facial expressions differed between all four SPs trained for that station.

CONCLUSIONS

Variation of trained SP portrayal of the same station across different tracks and at different times in OSCE may contribute substantial error to OSCE assessments. The training of SPs should be strengthened and constantly monitored during the exam to ensure that the examinees' scores are a true reflection of their competency and devoid of exam errors.

Risk factors associated with patency loss of hemodialysis vascular access within 6 months

BACKGROUND AND OBJECTIVES

Clinical guidelines support vascular access surveillance to detect access dysfunction and alter the clinical course by radiologic or surgical intervention. The objective of this study was to explore the association between loss of primary functional patency within 6 months of first use and demographic and clinical characteristics of patients receiving chronic renal replacement therapy with arteriovenous fistulas.

DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS

This was a retrospective study of all chronic hemodialysis patients followed by the Southern Alberta Renal Program from January 1, 2005 to June 30, 2008. Demographic and clinical variables and initial intra-access blood flow (IABF) were compared between those with and without loss of primary functional patency. To determine the contribution of independent variables to the dependant variable of loss of primary functional patency, a multivariable analysis using logistic regression was performed.

RESULTS

The incidence of primary failure was 10% (81 of 831). Multivariable analysis found that older age (>65 years, odds ratio [OR] 3.6, P < 0.001), history of diabetes (OR 2.3, P = 0.007), history of smoking (OR 4.3, P < 0.001), presence of forearm fistulas (OR 4.0, P < 0.001), and low initial IABF (<500 ml/min, OR 29, P < 0.001) were independently associated with loss of primary patency.

CONCLUSIONS

The set of patient risk factors identified in this study, particularly initial IABF, can be used to identify patients who are most at risk for developing vascular access failure and to guide a more directed approach for a vascular access screening protocol.

Assessment of live kidney donors by magnetic resonance angiography: reliability and impact on outcomes

BACKGROUND

Kidney allograft retrieval from live donors requires accurate determination of kidney anatomy prior to surgery, particularly the arterial supply. Traditionally, conventional angiography has been used to obtain this information. Magnetic resonance angiography (MRA) offers a non-invasive, cost-effective alternative, but has been considered to be less accurate. Despite this criticism, many centers have moved to MRA screening of potential kidney donors. The objective of this study is to evaluate our experience of the reliability of MRA in determining the arterial anatomy of living kidney donors as compared to the intra-operative findings.

METHODS

We performed a retrospective review of gadolinium-enhanced, ultra-fast, three-dimensional, spoiled gradient-echo MRA in live kidney donors in the Southern Alberta Transplant Program and compared these results with the intra-operative findings during nephrectomy, as the gold standard.

RESULTS

Of the 66 patients, an accessory renal artery was found intra-operatively in eight cases; two of which were erroneously diagnosed as normal by MRA. The negative predictive value for MRA was 0.97, false-negative rate was 0.25, and sensitivity was 0.75. No patient experienced side-effects from the MRA procedure. No donor needed conversion to open nephrectomy because of an undetected accessory renal artery. One allograft with an accessory renal artery developed thrombosis of the lower pole of the kidney despite arterial reconstruction. Kidney function in the recipient of this allograft was excellent and there was no urinary leak.

CONCLUSION

In our hands, MRA determined the vascular anatomy of potential kidney donors with an acceptable negative predictive value of 97%.

Bladder vs enteric drainage in simultaneous pancreas-kidney transplantation

BACKGROUND

As a valid therapeutic option for patients with type 1 diabetes mellitus (IDDM) and secondary diabetic nephropathy, simultaneous pancreas-kidney (SPK) transplantation remains more undeveloped than other solid organ transplantations due to restrictions of surgical techniques, especially modes of exocrine pancreatic secretion. Enteric drainage (ED) has recently been increasingly popular due to the long-term complications with bladder drainage (BD). Objectives. Compare results of SPK transplants with enteric vs bladder exocrine drainage since the beginning of our experience with this type of transplantation.

METHODS

From March 1998 to October 2004, 53 SPK transplants were performed, consisting of 30 with bladder drainage (BD) and 23 with enteric drainage (ED). Induction therapy included antilymphocyte globulin (ALG) or anti-CD25 monoclonal antibody. Maintenance regimen consisted of tacrolimus (TAC)/cyclosporine (CsA), mycophenolate mofetil (MMF) and steroids.

RESULTS

Mean age of recipients was 39+/-7 in both groups. No anastomosis leakage occurred in either group. Surgical complications were not significantly different between the two groups. Incidence of acute rejection, major infections and cytomegalovirus disease were also similar. However, the BD group was characterized by a slight increase in number of urologic complications, metabolic acidosis and dehydration. The length of initial hospital stay was likewise comparable. All patients with a functional graft no longer required exogenous insulin. BD actuarial patient survival and graft three-year survival were 96 and 86%, respectively. For ED, the respective results were 97 and 91%, respectively.

CONCLUSION

Compared with BD, perioperative morbidity is not increased by ED, and ED is not associated with increased long-term pancreas graft failure. These data suggest that ED is superior to BD and should be considered as the preferred technique for simultaneous pancreas-kidney transplants.

Use of a minimally invasive donor nephrectomy program to select technique for live donor nephrectomy

BACKGROUND

Live donor nephrectomy (LDN) is a major surgical procedure with an accepted low mortality and morbidity. Minimally invasive donor nephrectomy (MIDN) has been shown to decrease the wound morbidity associated with the lumbotomy of the classic open technique. Transplant programs face the challenge of initiating their MIDN programs without jeopardizing the safety of the donor and the graft quality. We present the experience at the University of Calgary after the initiation of a MIDN program, with a preoperative selective approach using the 3 major techniques for LDN.

METHODS

From December 2001 to May 2004, 50 consecutive, accepted, live kidney donors were evaluated and chosen to undergo nephrectomy by an open, laparoscopic, or hand-assisted technique. Patients were chosen for a particular technique based on the criteria of vascular anatomy, size of abdominal cavity, previous surgery, and technical implications for the recipient.

RESULTS

A total of 15 open, 11 laparoscopic, and 24 hand-assisted nephrectomies were performed. There were no statistically significant differences in sex, age, or body mass index between the groups. There were statistically significant differences in surgical times (P < .001) and in the number of days spent in the hospital (P < .001). All kidneys had primary function. There were 2 conversions in the hand-assisted group and 1 blood transfusion in the open group. Death-censored graft survival was 100% with an observation time of 20 months (SD +/- 9 months; range = 3-32 months). One graft from the hand-assisted group was lost from patient death with functioning graft 8 months after transplant.

CONCLUSIONS

The learning curve for MIDN does not necessarily need to impact donor or recipient outcomes. The initiation of an MIDN program can be implemented safely if the cases are selected carefully and the use of the classic open technique is kept as an alternative.