Interpretation of the Seattle Angina Questionnaire as an Outcome Measure in Clinical Trials and Clinical Care

Importance: Patient-reported outcomes are increasingly used as end points in clinical trials, assessments in clinical care, and tools for population health, with an increasing role in quality assessment. For patients with coronary artery disease, the Seattle Angina Questionnaire (SAQ) has emerged as the most commonly used measure of disease-specific health status to quantify patients' symptoms of angina and the extent to which their angina affects their functioning and quality of life. This review explains how to interpret the SAQ and describes the construction and face validity of the SAQ, focusing on aligning scores and changes in scores with clinical constructs. Observations: The SAQ asks questions similar to those an experienced clinician would ask of a patient with stable ischemic heart disease. Therefore, SAQ scores can be aligned with clinical constructs (eg, scores on the SAQ angina frequency scale of 0-30 points indicate daily angina, 31-60 points indicate weekly angina, 61-99 points indicate monthly angina, and 100 points indicate no angina), and changes in scores can be described by aligning them with changes in question responses. After clinical thresholds are defined, it is important for clinical trials to not simply report mean differences between treatment arms but to also report the distributions of patients who have had clinically important benefits so that a number needed to treat can be generated. Conclusions and Relevance: The widespread use of the SAQ is a consequence of its well-established validity, reproducibility, prognostic importance, and sensitivity to clinical change. Nevertheless, interpreting the SAQ can be challenging because of lack of familiarity with the clinical importance of its domains, either cross-sectionally or longitudinally. This review provides an overview of the interpretability of the SAQ as a foundation for its use as an end point in clinical trials, a tool to support more patient-centered care, and a means of facilitating population health strategies to provide a better foundation for the integration of patient experiences with clinical care.