Investigation of Validity and Reliability of Persian Version of the St. George Respiratory Questionaire

Health related quality of life (HRQL) questionnaires allow clinicians to measure daily the impact of disease on a patients daily life and is valuable in clinical trial designed to assess benefits and costs of management. We describe the adaptation into Persian version of the St.George Respiratory Questionnaires (SGRQ); a recognized valid self administered questionnaire for chronic obstructive pulomnary diseases. In order to adapt the face validity, the forward and back- translation method was used. Then this questionnaire was edited by researchers and a single pulmonologist as an internist. The content of tests evaluated for feasibility and comprehension by 15 educated COPD patients. In following, the professional committee of researcher assessed the content validity. At last, 55 COPD patients with wide range of disease severity fulfilled the Persian version of the SGRQ. Internal consistency were measured by Cronbach’s alpha coefficient test. The test coefficiency for reliability was 0.74 in part I of questionnaire; "symptoms". Factor analysis indicated that if latest question of part 1 was eliminated [“If you wheeze, is it become worse in the morning?”] Cronbach’s alpha would be elevated to 0.78. Cronbach’s alpha was 0.95 in Part II (Activity & impact) and for overall scale, the result was found to be 0.93. Data from this study revealed that Persian version of SGRQ, as a research tool, is of good validity and sufficient reliablity. The present study suggest the feasibility of adapting a specific instrument of health related quality of life in patients with respiratory disease to be used in different settings from where the instrument has been originally developed.