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.

Methods and 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.

Conflict of interest statement

Conflict of Interest Disclosures: No relevant disclosures were reported. Drs Curtis and Schulman have made available online detailed listings of financial disclosures (http://www.dcri.duke.edu/research/coi.jsp).

Figures

Figure 1

Histogram of Cumulative Cardiac Rehabilitation Sessions Attended During the First 36 Weeks After the Index Date

Figure 2

Cumulative Incidence of Mortality by Number of Cardiac Rehabilitation Sessions Attended

Figure 3

Cumulative Incidence of Myocardial Infarction by Number of Cardiac Rehabilitation Sessions Attended

Figure 4

Adjusted Relationships Between the Number of Cardiac Rehabilitation Sessions Attended and Mortality, Overall and by Indication Abbreviation: CABG, coronary artery bypass graft surgery. Note: Hazard ratios and 95% confidence intervals are plotted on the y-axes. Solid lines represent the estimated hazards of mortality or myocardial infarction associated with attending 0 to 36 cardiac rehabilitation sessions vs attending 36 sessions. Dashed lines represent the 95% confidence intervals around these estimates.

Figure 4

Adjusted Relationships Between the Number of Cardiac Rehabilitation Sessions Attended and Mortality, Overall and by Indication Abbreviation: CABG, coronary artery bypass graft surgery. Note: Hazard ratios and 95% confidence intervals are plotted on the y-axes. Solid lines represent the estimated hazards of mortality or myocardial infarction associated with attending 0 to 36 cardiac rehabilitation sessions vs attending 36 sessions. Dashed lines represent the 95% confidence intervals around these estimates.

Figure 4

Adjusted Relationships Between the Number of Cardiac Rehabilitation Sessions Attended and Mortality, Overall and by Indication Abbreviation: CABG, coronary artery bypass graft surgery. Note: Hazard ratios and 95% confidence intervals are plotted on the y-axes. Solid lines represent the estimated hazards of mortality or myocardial infarction associated with attending 0 to 36 cardiac rehabilitation sessions vs attending 36 sessions. Dashed lines represent the 95% confidence intervals around these estimates.

Figure 4

Adjusted Relationships Between the Number of Cardiac Rehabilitation Sessions Attended and Mortality, Overall and by Indication Abbreviation: CABG, coronary artery bypass graft surgery. Note: Hazard ratios and 95% confidence intervals are plotted on the y-axes. Solid lines represent the estimated hazards of mortality or myocardial infarction associated with attending 0 to 36 cardiac rehabilitation sessions vs attending 36 sessions. Dashed lines represent the 95% confidence intervals around these estimates.