Estimating the effects of exercise-based cardiac rehabilitation on health-related quality of life in patients with myocardial infarction in Sweden: A registry-based study using non-experimental methods

Participation in exercise-based cardiac rehabilitation (EBCR) improves long-term prognosis for patients following myocardial infarction (MI). Evaluating the effects of EBCR is challenging due to the voluntary nature of participation in the program. Using register data on 18,978 patients hospitalized for MI in 2011 to 2013 in Sweden, a non-experimental study design is employed to evaluate the effects of EBCR on the health-related quality of life (HRQoL). Conditional independence from non-random treatment assignment is considered through set of potential-outcome (PO) models to estimate the average treatment effect (ATE) and the ATE on the treated (ATET) of EBCR on HRQoL using the EQ-5D-3L instrument. Changes in the EuroQoL Visual Analogue Scale (EQ-VAS; range 0 to 100) and the EQ5D-Index (range -0.594 to 1) between 6-10 weeks and one-year post-MI are compared between two groups of participants in EBCR (complete participants [≥3 months] and non-complete participants [<3 months]) and non-participants (control group). In total, 43% of patients participated in EBCR to some extent (12% complete, 31% non-complete). Participants showed greater improvement on the EQ-VAS scale compared with non-participants. Patients who completed an EBCR program had a larger improvement (ATE of between 1.851-1.917 points; p < 0.001) compared with participants who did not complete the full program (0.974-1.017 points; p < 0.01). Full participation in the program increased the EQ5D-Index of between 0.014 and 0.017 points (p < 0.05), while no statistically significant effect was observed among non-completers. The effect of EBCR on HRQoL was more pronounced among younger patients and those reporting dyspnea and angina than older and non-symptomatic patients. Participating in EBCR may improve the health-related quality of life of patients post-MI. The clinical relevance of the observed impact of EBCR on HRQoL warrants further investigation. The effects of EBCR participation can be readily estimated using broadly applicable non-experimental approaches and commonly available register data.