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Socioeconomic Status and Kidney Transplant Outcomes in a Universal Healthcare System

A Population-based Cohort Study

Naylor, Kyla L., PhD1,2; Knoll, Gregory A., MD, MSc3; Shariff, Salimah Z., PhD1; McArthur, Eric, MSc1; Garg, Amit X., MD, PhD1,4,5; Van Walraven, Carl, MD, MSc1,6,7; Austin, Peter C., PhD1,2; McCallum, Megan K., MPH1; Quinn, Robert R., MD, PhD8; Tan, Vivian S., BMSc5; Kim, Joseph S., MD, PhD9

doi: 10.1097/TP.0000000000002383
Original Clinical Science—General: PDF Only

Background Conflicting evidence exists regarding the relationship between socioeconomic status (SES) and outcomes following kidney transplantation.

Methods We conducted a population-based cohort study in a publicly funded healthcare system using linked administrative healthcare databases from Ontario, Canada to assess the relationship between SES and total graft failure (ie, return to chronic dialysis, preemptive retransplantation, or death) in individuals who received their first kidney transplant between 2004 and 2014. Secondary outcomes included death-censored graft failure, death with a functioning graft, all-cause mortality and all-cause hospitalization (post hoc outcome).

Results 4414 kidney transplant recipients were included (median age, 53 years; 36.5% female) and the median (25th, 75th percentile) follow-up was 4.3 (2.1, 7.1) years. In an unadjusted Cox proportional hazards model, each $10 000 increase in neighborhood median income was associated with an 8% decline in the rate of total graft failure (hazard ratio 0.92 [95% confidence interval [CI]: 0.87, 0.97]). After adjusting for recipient, donor and transplant characteristics, SES was not significantly associated with total or death-censored graft failure. However, each $10 000 increase in neighborhood median income remained associated with a decline in the rate of death with a functioning graft (aHR 0.91, 95% CI: 0.83, 0.98), all-cause mortality (aHR 0.92, 95% CI: 0.86, 0.99) and all-cause hospitalization (aHR 0.95, 95% CI: 0.92, 0.98).

Conclusions In conclusion, in a universal healthcare system, SES may not adversely influence graft health but SES gradients may negatively impact other kidney transplant outcomes and could be used to identify patients at increased risk of death or hospitalization.

1Institute for Clinical Evaluative Sciences (ICES), Ontario, Canada

2Institute of Health Policy, Management, and Evaluation, University of Toronto, Toronto, Ontario, Canada

3Division of Nephrology, Kidney Research Centre, Ottawa Hospital Research Institute, University of Ottawa, Ottawa, Ontario, Canada

4Department of Epidemiology & Biostatistics, Western University, London, Ontario, Canada

5Division of Nephrology, Western University, London, Ontario, Canada

6Clinical Epidemiology Program, Ottawa Hospital Research Institute, Ontario, Canada

7Department of Medicine, University of Ottawa, Ontario, Canada.

8Departments of Medicine and Community Health Sciences, University of Calgary, Calgary, Ontario, Canada

9Division of Nephrology, University Health Network, University of Toronto, Toronto, Ontario, Canada

These authors contributed equally to this work. Kyla L. Naylor PhD, Gregory A. Knoll MD, MSc.

Correspondence: S. Joseph Kim, MD, PhD, MHS, FRCPC, Toronto General Hospital, 585 University Avenue, 11-PMB-129, Toronto, Ontario, Canada, M5G 2N2, Phone: 416-340-3228, Fax: 416-340-4701, Email: joseph.kim@uhn.ca

Author Contributions: S.J.K conceived of the study. S.Z.S and E.M provided analytic and statistical support. K.L.N drafted the manuscript. All authors read and approved the final manuscript.

Disclosures: Drs. Kim and Knoll have received investigator-initiated research grants from Canadian Institutes of Health Research and Astellas Canada. Dr. Garg received an investigator-initiated grant from Astellas for a Canadian Institutes of Health Research study in living kidney donors. Dr. Amit Garg was supported by the Dr. Adam Linton Chair in Kidney Health Analytics, and a Clinician Investigator Award from the Canadian Institutes of Health Research. Others: None to declare.

Funding: Kidney Foundation of Canada (KFOC110009)

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