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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., MD1; Shariff, Salimah Z., PhD1; McArthur, Eric, MSc1; Garg, Amit X., MD, PhD1,4,5; Van Walraven, Carl, MD1,6,7; Austin, Peter C., PhD1,2; McCallum, Megan K., MPH1; Quinn, Robert R., MD, PhD8; Tan, Vivian S., BMSc5; Kim, S. Joseph, MD, PhD, FRCPC9

doi: 10.1097/TP.0000000000002383
Original Clinical Science—General
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Background. Conflicting evidence exists regarding the relationship between socioeconomic status (SES) and outcomes after 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. Four thousand four hundred-fourteen 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 CAD $10000 increase in neighborhood median income was associated with an 8% decline in the rate of total graft failure (hazard ratio [HR], 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 CAD $10000 increase in neighborhood median income remained associated with a decline in the rate of death with a functioning graft (adjusted (a)HR, 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.

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

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

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

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

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

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

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

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

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

Received 7 March 2018. Revision received 28 June 2018.

Accepted 18 July 2018.

K.L.N. and G.A.K. contributed equally to this work.

S.J.K. and G.A.K. have received investigator-initiated research grants from Canadian Institutes of Health Research and Astellas Canada. A.X.G. received an investigator-initiated grant from Astellas for a Canadian Institutes of Health Research study in living kidney donors. A.X.G. 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.

Kidney Foundation of Canada (KFOC110009).

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

Supplemental digital content (SDC) is available for this article. Direct URL citations appear in the printed text, and links to the digital files are provided in the HTML text of this article on the journal’s Web site (www.transplantjournal.com).

Correspondence: S. Joseph Kim, MD, PhD, FRCPC, Toronto General Hospital, 585 University Ave, 11-PMB-129, Toronto, Ontario, Canada M5G 2N2. (joseph.kim@uhn.ca).

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