The Seattle Angina Questionnaire (SAQ)
The Seattle Angina Questionnaire is the most sensitive, specific, and responsive health-related quality of life instrument for coronary artery disease.
The SAQ is a self-administered, disease-specific measure for patients with CAD that is valid, reproducible, and sensitive to clinical change. This instrument was developed and validated by John Spertus, Director of Cardiovascular Education and Outcomes Research at the Mid America Heart Institute and Professor of Medicine at the University of Missouri – Kansas City.
The SAQ quantifies patients’ physical limitations caused by angina, the frequency of and recent changes in their symptoms, their satisfaction with treatment, and the degree to which they perceive their disease to affect their quality of life. Each scale is transformed to a score of 0 to 100, where higher scores indicate better function (eg, less physical limitation, less angina, and better quality of life).
Validity refers to the degree to which an instrument measures what it is supposed to measure. During development, each SAQ scale was evaluated against appropriate standard clinical measures:
Physical Limitation Scale
Patients with coronary artery disease (CAD) underwent treadmill testing. The age-adjusted correlation between exercise duration and the Physical Limitation Scale exceeded that of comparison measures (DASI score, SF-36 physical score, SAS score, and CCSC score): r = 0.42 (p=0.001).
Anginal Stability Scale
Among a cohort of patients with initially stable angina, there was a significant correlation between the Anginal Stability Scale and patients’ perception of global change after 3 months: r = 0.70 (p<0.0001).
Anginal Frequency Scale
Patients with initially stable coronary artery disease demonstrated a correlation between Anginal Frequency Scale sores and 1-year nitroglycerin refills: r = 0.31 (p=0.0006).
Treatment Satisfaction Scale
Treatment Satisfactory Scale scores of patients with CAD were highly correlated with the American Board of Internal Medicine’s Patient Satisfaction Questionnaire: r = 0.67 (p<0.0001).
Disease Perception Scale
Disease Perception Scale scores of patients with stable angina and patients undergoing angioplasty were highly correlated with the general health perceptions scale of the SF-36: r = 0.67 (p<0.0001).
Reliability and Responsiveness
In the validation studies, all scales decreased in the group that reported worsening, remained unchanged in the patients with initially stable CAD, and increased among patients who reported an improvement:
The minimal clinically-significant change in each scale is a change of 10 points.
The SAQ’s ability to document improvement is particularly apparent, as seen in the dramatic increase in scale scores after successful angioplasty:
Created: April 28, 2004 20:41
Last updated: December 16, 2015 16:40