Validation of the Seattle Angina Questionnaire in patients with myocardial infarction

The short version of the Seattle Angina Questionnaire-7 (SAQ-7) is widely used in patients with coronary artery disease, but its use in patients post myocardial infarction (MI) is limited. This study aimed to validate the SAQ-7 in patients post-MI. A longitudinal cohort study was conducted with 258 stable participants with MI recruited from different outpatient cardiology clinics. Participants with cardiologist-confirmed MI, stable ≥4 weeks were included in the study, while participants with ejection fraction <40%, neurological or musculoskeletal disorders were excluded. Participants completed the SAQ-7, European quality of life-five dimensions-five levels (EQ-5D-5L), and Short Form 12 (SF-12) at baseline. Questionnaires were self-administered, and assistance was given when required. A subset of 117 participants returned 3 to 10 days later for a follow up to assess test-retest reliability. Participants completed the SAQ-7 alongside with a global rating of change scale (GRC). Cronbach alpha and intraclass correlation coefficient (ICC2,1) were used to examine internal consistency and test-retest reliability, respectively. Construct validity was determined via correlations with EQ-5D-5L and SF-12 scores. The SAQ-7 demonstrated excellent internal consistency (Cronbach alpha = 0.97) and test-retest reliability (ICC2,1 = 0.94; 95% CI: 0.92-0.96, P <.001). The SAQ-7's measurement error was 1.76, with a minimum detectable change at 95% confidence of 4.87 points. The Bland and Altman analysis showed a mean difference of 0.75 with narrow limits of agreement. The SAQ-7 correlated strongly with EQ-5D-5L (r = -0.86, P <.001) and moderately with the SF-12 Physical (R = 0.74, P <.001) and Mental (R = 0.57, P <.001) components scores. No floor or ceiling effects were observed. The SAQ-7 demonstrated excellent psychometric properties in post-MI, supporting its use for health related quality of life assessment. However, these findings should be interpreted in the context of the study population and design.