Compared with other modes of renal replacement therapy, kidney transplantation offers improved survival and quality of life. However, life expectancy among kidney transplant recipients is lower than that in the general population. Cardiovascular disease is one factor that contributes to the increased rates of mortality in the transplant population; heart failure, myocardial infarction, and stroke occur frequently in the first 3 years post-transplantation. In the first and second years following kidney transplantation, heart failure is the most common primary cardiovascular diagnosis for hospitalized kidney transplant recipients. There is an association between posttransplant diagnosis of heart failure and reduced graft and patient survival.
Studies conducted among the general population have demonstrated a decrease in the incidence of heart failure during the past two decades. There are few data available in whether a similar trend exists in the kidney transplantation population. Colin R. Lenihan, MB BCh, BAO, PhD, and colleagues conducted a retrospective observational cohort study designed to examine secular trends in the incidence of de novo heart failure following kidney transplantation and the associated mortality between 1998 and 2010. Results of the study were reported in the American Journal of Kidney Diseases [2018;72(2):223-233].
Study participants were adult patients in the US Renal Data System who underwent their first kidney transplantation in the United States between 1998 and 2010. Eligible patients had at least 6 months of continuous Medicare parts A and B coverage prior to transplantation and no prior evidence for a diagnosis of heart failure prior to transplantation.
The outcomes of interest were de novo post-transplantation heart failure defined using diagnosis codes from the International Classification of Diseases, Ninth Revision, and mortality following de novo heart failure diagnosis post-transplantation. Cox proportional hazards analysis was used to examine secular trends in de novo post-kidney transplantation heart failure.
A total of 48,771 patients met eligibility criteria. Between 1998 and 2010, there were increases in age at transplantation, body mass index (BMI), and dialysis vintage in the study population. There were also increases in the prevalence of comorbid conditions at baseline, including diabetes mellitus, coronary artery disease, peripheral arterial disease, and hypertension during the study period.
Of the 48,771 patients, 7269 developed de novo heart failure within the first three years after kidney transplantation. Median time to diagnosis was 0.76 years. Following adjustment for all available demographic data, comorbid conditions, and transplantation characteristics, the risk for developing de novo heart failure in the first 3 years following kidney transplantation was 31% lower for patients who underwent the procedure in 2010 compared with those who underwent transplantation in 1998 (hazard ratio, 0.69; 95% confidence interval, 0.60-0.79).
Results were similar in sensitivity analyses that (1) treated death and graft failure as competing risks, (2) treated death and graft failure as censoring events, (3) treated death as a competing risk and excluded graft failure from the analysis, and (4) treated death as a censoring event and excluded graft failure.
In analyses limited to the subgroup of patients who were diagnosed with de novo heart failure, graft failure occurring prior to heart failure diagnosis, defined as post-transplantation return to dialysis or retransplantation, was included as an additional baseline value. There was no temporal trend in the probability of death following a diagnosis of de novo heart failure within 3 years of kidney transplantation during the study period.
When the analyses were limited to complete cases only, results were similar. In a parallel analysis that required 1 year of Medicare parts A and B coverage prior to transplantation (n=47,054), and identification of pre-existing heart failure was limited to medical claims in the year prior to the procedure, the secular trend in de novo post-transplantation heart failure was nearly identical to that of the main analysis.
The relative impact of each individual covariate was assessed using one-at-a-time analysis. The most consistent confounders across the study period for the outcome of de novo post-kidney transplantation heart failure were recipient age, recipient sex, BMI, graft failure, and dialysis vintage. For the outcome of mortality, the most consistent confounders were recipient age, recipient sex, and transplant vintage.
There were some limitations to the study cited by the authors, including the potential for residual confounding from either incorrectly ascertained or unavailable confounders, and including only Medicare beneficiaries in the study population.
“in conclusion, the adjusted incidence of de novo post-kidney transplantation heart failure has declined significantly in the kidney transplantation population in 1998 to 2010. Further studies are required to identify factors contributing to this positive trend,” the researchers said.
- Recipients of kidney transplantation have lower life expectancy than the general population, due, in part, to cardiovascular disease; a post-transplantation diagnosis of heart failure is associated with reduced graft and patient survival.
- In a retrospective observational cohort study of Medicare beneficiary kidney transplant recipients from 1998 to 2010 (n=48,771), researchers sought to examine secular trends in the incidence of de novo heart failure within 3 years of kidney transplantation, as well as associated mortality.
- Of the 48,771 patients, 7269 developed de novo heart failure within 3 years post-transplant. There was no temporal trend in mortality following a diagnosis of de novo heart failure following kidney transplantation.