Psychometric Properties of the Seattle Angina Questionnaire (SAQ): Scale for Assessing Health-Related Quality of Life in Patients with Coronary Artery Disease

Aim and Seattle Angina Questionnaire (SAQ) has been designed to measur health-related quality of life (HRQOL) in patients with coronary artery disease (CAD). The psychometric properties of the questionnaire were evaluated in different countries as it was used widely in CAD patient’s quality of life research. The aim of this research was to investigate normalization, reliability and validity of this questionnaire in Iran.
Methods and Materials: Two hundred seventy nine patients with CAD were selected by convinience sampling method from Tehran Heart Center and asked to answer SAQ.
Findings: Using exploratory factor analysis by principal components analysis and Varimax rotation, six factors were extracted, including physical limitations caused by light activity, physical limitations caused by heavy activity, treatment satisfaction, quality of life, the problem of angina and chest tightness, and obligation in taking medication. These factors explained 66.16% of items variance. In confirmatory factor analysis, the six-factor model of this questionnaire in Iranian population was more desirable than the five-factor model of the original scale. Cronbach’s alpha of this questionnaire was 0.77 showing an acceptable internal consistency. According to score distribution and T score, mean HRQOL score was about 61 in CAD patients with the cut off point of 82.
SAQ is a valid and reliable instrument for assessing health related quality of life of patients with CAD, therefore it can be used in research and clinical settings in Iran.