Patients are referred to exercise-based cardiac rehabilitation (ECR) to increase exercise capacity and health-related quality of life (HRQOL) and thereby reduce risk of morbidity and mortality. The purpose of this study was to examine the correlation between exercise capacity and HRQOL. Furthermore, this study examined whether improvements in HRQOL were directly related to improvements in exercise capacity.
The study included 277 patients participating in ECR. HRQOL was assessed using the Medical Outcomes Study 36-item Short Form Health Survey (SF-36), and exercise capacity was measured as peak oxygen uptake (VO2peak) and oxygen uptake (VO2) at the ventilatory threshold (VTh). Patients were examined before and after completion of an 8-wk ECR program.
Analyses at baseline showed a significant correlation between VO2peak and VTh and physical functioning (PF), role limitations because of physical problems (RP), general health perceptions (GH), vitality (VT), and physical component summary (PCS) on the SF-36; PF was the only dimension showing a moderate correlation (>0.40 Spearman ρ) with VO2peak. The follow-up analyses demonstrated a significant correlation between changes in VO2peak and changes in PF, RP, VT, and MH. Changes in VO2 peak explained 4% of the changes in the PF and VT scores.
The correlations between exercise capacity and HRQOL were weak and varied considerably among patients. The ECR program improved both exercise capacity and HRQOL, but it was not necessarily the same patients who improved both parameters. Therefore, it is recommended to use separate objective measures and patient-reported outcomes when evaluating the effect of ECR.