Geographic variation in implantable cardioverter-defibrillator use and heart failure survival

Abstract

Background: Implantable cardioverter-defibrillators and cardiac resynchronization therapy-defibrillators (ICD/CRT-Ds) are evidence-based preventative treatments for many patients with heart failure (HF), yet large numbers of eligible patients remain untreated. It is uncertain if localities with more frequent ICD/CRT-D use have had better rates of HF survival.

Objectives: To determine if US Hospital Referral Regions (HRRs) with larger increases in the rate of ICD/CRT-D utilization during 2002 to 2007 also had commensurate increases in HF survival.

Research design: Retrospective cohort.

Participants: Medicare beneficiaries age 66 to 80 nonelectively hospitalized for HF from 2002 to 2007.

Measures: Each HRR's annual ICD/CRT-D rate was estimated from the cohort's Medicare procedure claims. Survival duration was determined from Medicare mortality records. HRR-year-level panel regression models were estimated to assess whether an HRR's ICD/CRT-D rate predicted HF survival, adjusting for baseline differences in survival across HRRs and secular trends.

Results: A total of 883,002 HF patients were propensity-score matched within HRR across 2002 to 2007. Across HRRs, growth in ICD/CRT-D use among such patients varied from 1 to 12 percentage points. Regression models indicated that a 1 percentage point increase in an HRR's ICD/CRT-D utilization among hospitalized HF patients was associated with an increase in 1-year survival of 0.12% [95% confidence interval (CI), 0.03%-0.21%, P=0.009] and with a 0.26% increase in HF survival at 2 years (95% CI, 0.14%-0.37%, P<0.001).

Conclusions: Localities with greater increases in ICD/CRT-D utilization from 2002 to 2007 also had greater improvements in HF survival. Areas with persistently low ICD/CRT-D use may be good targets for programs designed to increase the evidence-based use of defibrillators.

Figure

Location of low-use hospital referral regions, 2006–2007. The dark blue areas indicate HRRs in the lowest quintile (i.e., bottom 20% of HRRs) of ICD/CRT-D utilization among study cohort heart failure patients during 2006–2007. The light blue areas indicate HRRs in the second lowest quintile of ICD/CRT-D utilization among study cohort heart failure patients during 2006–2007. Abbreviations: ICD/CRT-D—implantable cardioverter defibrillator/cardiac resynchronization therapy defibrillator; HRR—hospital referral region.