Background-The benefit of a primary prevention implantable cardioverter defibrillator (ICD) among patients with chronic kidney disease (CKD) is uncertain.

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Background The impact of patient age on the risks of death or rehospitalization after primary prevention implantable cardioverter-defibrillator (ICD) placement is uncertain. Methods and Results Data from 5 major ICD trials were merged: MADIT-I, MUSTT, MADIT-II, DEFINITE, and SCD-HeFT . Median age at enrollment was 62 (interquartile range 53-70) years. Compared with their younger counterparts, older patients had a greater burden of comorbid illness. In unadjusted exploratory analyses, ICD recipients were less likely to die than non-recipients in all age groups: hazard ratio (HR) 0.48, 95% posterior credible interval (PCI) 0.33-0.69 among patients <55 years; HR 0.69, 95%PCI 0.53-0.90 among patients 55-64 years; HR 0.67, 95%PCI 0.53-0.85 among patients 65-74 years; and HR 0.54, 95%PCI 0.37-0.78 among patients > 75 years. Sample sizes were limited among patients > 75 years. In adjusted Bayesian Weibull modeling, point estimates indicate ICD efficacy persists but is attenuated with increasing age. There was evidence of an interaction between age and ICD treatment on survival (two-sided posterior tail probability of no interaction < 0.01). Using an adjusted Bayesian logistic regression model, there was no evidence of an interaction between age and ICD treatment on rehospitalization (two-sided posterior tail probability of no interaction 0.44). Conclusions In this analysis, the survival benefit of the ICD exists but is attenuated with increasing age. The latter finding may be due to the higher burden of comorbid illness, competing causes of death, or limited sample size of older patients. There was no evidence that age modifies the association between ICD treatment and rehospitalization.