Aims: To compare the psychometric properties of the World Health Organization Quality of Life-BREF (WHOQOL-BREF) instrument and the St. George's Respiratory Questionnaire (SGRQ), and to examine the association between pulmonary function and domains and items of these questionnaires in patients with chronic obstructive pulmonary disease (COPD).
Methods: The WHOQOL-BREF and the SGRQ were administered to 211 patients. The reliability and validity of, and correlations among, the domain scores were examined. Multiple regression analyses were performed to identify which items were independently associated with subjects' lung functions.
Results: Both questionnaires showed good internal consistency (alpha > 0.8), except the SGRQ symptoms domain (alpha = 0.66), minimal ceiling and floor effects, and good item convergent and item discriminant validity. There were moderate correlations between physical domain of the WHOQOL-BREF and activity, impacts and total domains of the SGRQ, and between psychological domain of the WHOQOL-BREF and impacts and total domains of the SGRQ. Eighteen items were significantly associated with lung function, particularly those items relating to mobility/walking and activities of daily living (ADL).
Conclusion: Both the WHOQOL-BREF and the SGRQ showed comparable reliability and validity. Items related to mobility/walking and ADL may be useful in clinical screening for lung function impairment.