The survival benefit conferred by implantable cardioverter-defibrillators (ICDs) persists with increasing patient age, but does attenuate, according to a report published online Feb.10 in Circulation: Cardiovascular Quality and Outcomes.

This indicates that “age per se should not be a contraindication to ICD placement. Rather, clinical judgment should take into account other factors, including patient preference, periprocedural risk, and comorbidity burden,” said Dr. Paul L. Hess of Duke Clinical Research Institute, Durham N.C., and his associates.

It is uncertain whether ICDs are effective at reducing sudden cardiac death in patients aged 75 years and older, largely because this age group has been underrepresented in clinical trials. Yet more than 40% of new ICDs are placed in older patients, including 10% placed in patients aged 80 years and older. Dr. Hess and his colleagues pooled data from five major clinical trials of ICDs to increase the sample size of older patients, allowing better appraisal of treatment effects in this age group. They retrospectively assessed survival outcomes in 3,530 patients who participated in the MADIT-I, MUSTT, MADIT-II, DEFINITE, and SCD-HeFT studies conducted in the United States, Canada, Italy, Germany, the Netherlands, and Israel.

The median age in this pooled sample was 62 years. There were 390 patients (11%) aged 75 years and older. Median follow-up after ICD placement was 2.6 years.

The primary outcome of interest – all-cause mortality – was 21.3% among ICD recipients, compared with 30.6% in patients who didn’t receive ICDs. “After adjusting for patient demographics, medical comorbidities, and laboratory values, point estimates indicated that the survival benefit of ICD therapy persists across the age spectrum,” the investigators said (Circ. Cardiovasc. Qual. Outcomes 2015 Feb. 10; [doi:10.1161/circoutcomes.114.001306]).

The survival benefit attenuated with increasing patient age. This may be because of an increase in competing causes of death as patients aged. However, the total number of participants aged 75 years and older was “modest” despite the pooling of data, “and this may have affected the corresponding efficacy estimates and the observed attenuation of ICD survival benefit,” Dr. Hess and his associates wrote.

The study also found no evidence that age influences the risk of rehospitalization after ICD placement.