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Reliability of World Health Organization's Quality of Life-BREF versus Short Form 36 Health Survey questionnaires for assessment of quality of life in patients with coronary artery disease

Objective The objective of this study was to ascertain the reliability and predictive power of the World Health Organization's Quality of Life Questionnaire (WHOQOL-BREF) and Short Form 36 Health Survey questionnaire (SF-36) in coronary artery disease patients. Methods Between May and September 2006, patients with coronary artery disease hospitalized in Tehran Heart Center were divided randomly into two groups of 268 patients (for assessment of QOL with the SF-36 questionnaire) and 275 patients (for assessment of QOL with the WHOQOL-BREF questionnaire). Cronbach's α coefficient was used to test reliability of the two questionnaires and a value of 0.7 or higher was considered satisfactory. Results For the SF-36 and the WHOQOL-BREF questionnaires, Cronbach's α was 0.825 and 0.701, respectively, both of which exceeded 0.7. In SF-36 questionnaire, with the deletion of four items in the scales of mental health (1), role limitation - physical (16), and bodily pain (19), Cronbach's α was significantly increased. Also, in the BREF questionnaire, deletion of each of items 3, 4, 8, 9, 22, and/or 26 led to an increase in Cronbach's α. Conclusion Although the WHOQOL-BREF questionnaire is a reliable tool for the evaluation of QOL in coronary artery disease patients, its reliability was significantly lower than that of the SF-36 questionnaire and thus it can be less applicable than SF-36 for this purpose.