Systematic review of statistical methods used to analyze Seattle Angina Questionnaire scores.
BACKGROUND
The Seattle Angina Questionnaire (SAQ) is being used with increasing frequency in clinical research to address the health-related quality of life (HRQOL) outcomes of patients with coronary artery disease. The reliability and validity of the SAQ as a disease-specific HRQOL questionnaire has been established. The purpose of this paper was to systematically identify all studies analyzing SAQ scores, and to review the suitability of the statistical methods used.


METHODS
The literature search included all years from the development of the SAQ (1994) to December 2001. Electronic databases were searched using 'Seattle angina questionnaire' as a key word, text word or medical subject heading, as well as combinations of Seattle, angina and questionnaire. The Scientific Citation Index was searched to identify any manuscripts that cited the developmental articles of the SAQ. Relevant manuscripts were identified as studies that used the SAQ as a measurement tool for HRQOL outcome data.


RESULTS
Of the 62 studies identified, 14 articles used the SAQ as an outcome measurement tool. The statistical validity of all but one of the 14 studies was doubtful because assumptions required for the use of parametric tests were not addressed and there was no mention of the distributions of the SAQ scores. Based on the designs of the studies, unsuitable analysis methods were used.


CONCLUSIONS
Our results demonstrate that investigators may need to increase their attention to the distributional characteristics of their HRQOL data and the design of the study before applying statistical tests to appropriately analyze SAQ HRQOL data.
Norris
Colleen M
CM
Faculty of Nursing, University of Alberta, Edmonton, Canada.
Ghali
William A
WA
Saunders
L Duncan
LD
Brant
Rollin
R
Galbraith
P Diane
PD
D000787:Angina Pectoris / Q000453:epidemiology*; D003324:Coronary Artery Disease / Q000453:epidemiology; D003627:Data Interpretation, Statistical; D006801:Humans; D017063:Outcome Assessment, Health Care / Q000706:statistics & numerical data; D011788:Quality of Life; D015203:Reproducibility of Results; D018434:Sickness Impact Profile; D011795:Surveys and Questionnaires