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Trends in the Medical Complexity and Outcomes of Medicare-insured Patients Undergoing Kidney Transplant in the Years 1998–2014

Lenihan, Colin R. MB, BCh, PhD1; Liu, Sai MPH1; Montez-Rath, Maria E. PhD1; Winkelmayer, Wolfgang C. MD, ScD2

doi: 10.1097/TP.0000000000002670
Original Clinical Science–General

Background. Graft and patient survival following kidney transplant are improving. However, the drivers of this trend are unclear. To gain further insight, we set out to examine concurrent changes in pretransplant patient complexity, posttransplant survival, and cause-specific hospitalization.

Methods. We identified 101 332 Medicare-insured patients who underwent their first kidney transplant in the United States between the years 1998 and 2014. We analyzed secular trends in (1) posttransplant patient and graft survival and (2) posttransplant hospitalization for cardiovascular disease, infection, and cancer using Cox models with year of kidney transplant as the primary exposure of interest.

Results. Age, dialysis vintage, body mass index, and the prevalence of a number of baseline medical comorbidities increased during the study period. Despite these adverse changes in case mix, patient survival improved: the unadjusted and multivariable-adjusted hazard ratios (HRs) for death in 2014 (versus 1998) were 0.61 (confidence interval [CI], 0.52-0.73) and 0.46 (CI, 0.39-0.55), respectively. For graft failure excluding death with a functioning graft, the unadjusted and multivariable adjusted subdistribution HRs in 2014 versus 1998 were 0.4 (CI, 0.25-0.55) and 0.45 (CI, 0.3-0.6), respectively. There was a marked decrease in hospitalizations for cardiovascular disease following transplant between 1998 and 2011, subdistribution HR 0.51 (CI, 0.43-0.6). Hospitalization for infection remained unchanged, while cancer hospitalization increased modestly.

Conclusions. Medicare-insured patients undergoing kidney transplant became increasingly medically complex between 1998 and 2014. Despite this, both patient and graft survival improved during this period. A marked decrease in serious cardiovascular events likely contributed to this positive trend.

1 Division of Nephrology, Department of Medicine, Stanford School of Medicine, Palo Alto, CA.

2 Selzman Institute for Kidney Health, Section of Nephrology, Department of Medicine, Baylor College of Medicine, Houston, TX.

Received 18 September 2018. Revision received 15 January 2019.

Accepted 1 February 2019.

The authors declare no conflicts of interest.

C.R.L. was involved in conception and design of the work, design and interpretation of data for the analysis, and drafting the first version of the manuscript and revising it critically for important intellectual content. S.L. and M.E.M.-R. were involved in design and interpretation of data for the analysis and revising the manuscript critically for important intellectual content. W.C.W. was involved in conception and design of the work, acquisition and interpretation of the data for the manuscript, and revising the manuscript critically for important intellectual content. All authors give final approval of the submitted manuscript.

C.R.L. was supported by a Mentored Clinical and Population Research Program Grant from the American Heart Association Western States Affiliate. W.C.W. received grant R01DK095024 from the National Institute of Diabetes, Digestive, and Kidney Diseases and received salary and research support from the endowed Gordon A. Cain Chair in Nephrology at Baylor College of Medicine. The funders of this study had no role in study design, collection, analysis, interpretation of data, writing, or the decision to submit the report for publication.

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Correspondence: Colin R. Lenihan, MB, BCh, PhD, Division of Nephrology, Department of Medicine, Stanford University School of Medicine, 777 Welch Road Suite DE, Palo Alto, CA 94304. (

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