title: Relationship between cardiac rehabilitation and long-term risks of death and myocardial infarction among elderly Medicare beneficiaries.
abstract: BACKGROUND
  For patients with coronary heart disease, exercise-based cardiac rehabilitation improves survival rate and has beneficial effects on risk factors for coronary artery disease. The relationship between the number of sessions attended and long-term outcomes is unknown.
  
  
  RESULTS
  In a national 5% sample of Medicare beneficiaries, we identified 30 161 elderly patients who attended at least 1 cardiac rehabilitation session between January 1, 2000, and December 31, 2005. We used a Cox proportional hazards model to estimate the relationship between the number of sessions attended and death and myocardial infarction (MI) at 4 years. The cumulative number of sessions was a time-dependent covariate. After adjustment for demographic characteristics, comorbid conditions, and subsequent hospitalization, patients who attended 36 sessions had a 14% lower risk of death (hazard ratio [HR], 0.86; 95% confidence interval [CI], 0.77 to 0.97) and a 12% lower risk of MI (HR, 0.88; 95% CI, 0.83 to 0.93) than those who attended 24 sessions; a 22% lower risk of death (HR, 0.78; 95% CI, 0.71 to 0.87) and a 23% lower risk of MI (HR, 0.77; 95% CI, 0.69 to 0.87) than those who attended 12 sessions; and a 47% lower risk of death (HR, 0.53; 95% CI, 0.48 to 0.59) and a 31% lower risk of MI (HR, 0.69; 95% CI, 0.58 to 0.81) than those who attended 1 session.
  
  
  CONCLUSIONS
  Among Medicare beneficiaries, a strong dose-response relationship existed between the number of cardiac rehabilitation sessions and long-term outcomes. Attending all 36 sessions reimbursed by Medicare was associated with lower risks of death and MI at 4 years compared with attending fewer sessions.
authors.affiliation: Center for Clinical and Genetic Economics, Duke Clinical Research Institute, PO Box 17969, Durham, NC 27715, USA. brad.hammill@duke.edu
authors.forename: Bradley G
authors.initials: BG
authors.lastname: Hammill
authors.forename: Lesley H
authors.initials: LH
authors.lastname: Curtis
authors.forename: Kevin A
authors.initials: KA
authors.lastname: Schulman
authors.forename: David J
authors.initials: DJ
authors.lastname: Whellan
mesh_terms: D000368:Aged; D001071:Appointments and Schedules; D015897:Comorbidity; D003324:Coronary Artery Disease / Q000401:mortality / Q000534:rehabilitation; D005081:Exercise Therapy / Q000706:statistics & numerical data*; D005260:Female; D006331:Heart Diseases / Q000401:mortality* / Q000534:rehabilitation*; D006333:Heart Failure / Q000401:mortality / Q000534:rehabilitation; D006760:Hospitalization / Q000706:statistics & numerical data; D006801:Humans; D008297:Male; D006278:Medicare / Q000706:statistics & numerical data*; D009203:Myocardial Infarction / Q000401:mortality / Q000534:rehabilitation; D017063:Outcome Assessment, Health Care; D011237:Predictive Value of Tests; D016016:Proportional Hazards Models; D012307:Risk Factors; D016896:Treatment Outcome; D014481:United States / Q000453:epidemiology