Patterns of Care and Outcomes in Cardiovascular Disease After Kidney Transplantation in the United States

Abstract

Background: Cardiovascular disease (CVD) is an important driver of mortality after kidney transplantation. Its broader impact on posttransplant health care utilization in US hospitals is unknown.

Methods: We used administrative claims data from the Nationwide Inpatient Sample and the American Hospital Association Annual Survey to identify hospitalizations for kidney transplant patients with a cardiovascular diagnosis from 2005 to 2011. CVD hospitalizations were stratified by transplant hospital status to characterize patterns in inpatient health care utilization and outcomes. Based on these analyses, the domestic burden of treatment for posttransplant CVD (myocardial infarction, stroke, congestive heart failure, dysrhythmia, cardiac arrest, malignant hypertension) was estimated.

Results: The total domestic burden of post-kidney transplant hospitalization between 2005 and 2011 is estimated at 389 138 of which 26.5% of episodes were related to CVD (n = 103 118). CVD was responsible for a growing proportion of post-transplant hospitalizations over time (24.4%-30.4%, P < 0.001). Compared with nontransplant hospitals, transplant hospitals had similar length of stay (median length of stay, 3.7 days), higher median costs per hospitalization (US $10 364 vs US $8606, overall US $9324), and lower adjusted mortality (3.2% vs 3.9%, overall 3.6%; P = 0.003).

Conclusions: Inpatient CVD care is increasing over time for kidney transplant patients, accounting for 30% of all post-transplant hospitalizations. Variation exists in the inpatient care, outcomes, and costs between by hospital type. Further studies are needed to better understand the mechanisms behind these phenomena.

FIGURE 1

Hospitalizations for CVD after kidney transplantation in transplant and non-transplant hospitals, 2005 to 2011. Over the study period, there were 103118 hospitalizations in the United States that occurred after kidney transplantation. By 2011, more than 30% of these hospitalizations were attributable to CVD, totaling more than 16000 admissions (square solid line, left y-axis). Relative to all post-transplant admissions, non-transplant hospitals (triangle dash) had significantly higher proportions of CVD admissions compared to transplant hospitals (circle dash) (right y-axis). 58.3% of all post-kidney transplant CVD admissions in 2011 occurred in non-transplant facilities (17.7% of all post-transplant admissions) (not shown).

FIGURE 2

CVD Hospitalizations after Kidney Transplantation by Diagnosis, 2005-2011. This figure demonstrates diagnosis-specific trends in hospital admissions over the study period attributable to MI, stroke, CHF, Dysrhythmia, Cardiac Arrest, and malignant hypertension. Over the study period, there was a statistically significant increase in admissions for MI, accounting for 2.6% of all post-kidney transplant hospitalizations (P < 0.05). Stroke admissions declined slightly. The most significant increases were observed in more documented primary-diagnosis admissions for CHF and dysrhythmia (P = 0.01), accounting for 16% to 17% of all hospital admissions respectively. Cardiac arrest and malignant hypertension accounted for just over 1% of all post-kidney transplant hospital admissions across the study period.