Effect of Advancing Age and Multiple Chronic Conditions on Mortality in Patients with End-Stage Renal Disease after Implantable Cardioverter-Defibrillator Placement

CONTEXT: There is insufficient information on the effect that advancing age and multiple chronic conditions (MCC) have on mortality after placement of an implantable cardioverter-defibrillator in patients with end-stage renal disease (ESRD) vs non-ESRD. OBJECTIVE: To assess whether a differential effect of age and MCC exists between ESRD and non-ESRD. DESIGN: Population-based, retrospective cohort study using data from the national Kaiser Permanente Cardiac Device Registry of patients who underwent placement of an implantable cardioverter-defibrillator between January 1, 2007, and December 31, 2013. MAIN OUTCOME MEASURES: All-cause mortality. RESULTS: Of 7825 patients with implantable cardioverter-defibrillator placement, ESRD-affected patients constituted 4.0% of the cohort (n = 311), were similar in age (p = 0.91), and presented with a larger comorbidity burden (3.3 ± 1.3 vs 2.4 ± 1.5, p < 0.001). The effect of advancing age (every 5 years) on mortality in the ESRD cohort (hazard ratio [HR] = 1.11, 95% confidence interval [CI] = 1.03-1.20) was less than in the non-ESRD cohort (HR = 1.28, 95% CI = 1.25-1.32). Similarly, the effect of each additional comorbidity in the ESRD cohort was less (HR = 1.04, 95% CI = 0.91-1.19) than in the non-ESRD group (HR = 1.20, 95% CI = 1.16-1.25). Lastly, ESRD was independently associated with a 3-fold greater hazard of mortality. CONCLUSIONS: Advancing age and increasing number of MCC have a differential effect on mortality risk in patients with ESRD compared with their non-ESRD counterparts. Future studies should focus on assessment of nonlinear relationships of age, MCC, and naturally occurring clusters of MCC on mortality.