The role of seasonality on evaluating health-related quality of life in patients with coronary artery disease.

Comparing data from different years and the time of year during which data are collected can affect respondents' answers or health status. This study investigated the possible association between seasonality and the self-reported health-related quality of life (HRQoL) of patients with coronary artery disease (CAD) during rehabilitation and at a 2-year follow-up. The study included 1026 respondents (79% men; mean age 56 ± 9 years). Baseline characteristics covered socio-demographic, clinical factors, and psychological assessments using the Hospital Anxiety and Depression Scale. HRQoL was evaluated using the 36-item Short Form Medical Outcome Questionnaire (SF-36) and the Minnesota Living with Heart Failure Questionnaire (MLHFQ). The MLHFQ data were collected longitudinally. The results of the multivariable linear regression confirmed a potential association between seasonality and self-reported HRQoL as assessed during cardiac rehabilitation period in patients with CAD. According to the SF-36, the summer season was associated with improved mental health outcomes, while the winter season was significantly linked to better scores in the pain domain. Based on the MLHFQ data, the winter season was associated with better overall HRQoL both during rehabilitation and at the 2-year follow-up. Similarly, the MLHFQ physical dimension showed better scores in winter at the 2-year follow-up, but not at baseline.