Background: The St. George's Respiratory Questionnaire (SGRQ) is a 50-item health status survey specific for chronic obstructive pulmonary disease (COPD) and other respiratory diseases that is available in British English but not American English. The SGRQ's symptom-reporting component requires a 1-year reporting period, which may be too long for reliable and accurate patient recall.
Objectives: The objectives of the present study were to translate the SGRQ from British to American English, modify the reporting period of the symptom-reporting component from 1 year to 1 month, and assess the reliability, validity, and sensitivity to change of this translated modified version in a sample of patients with COPD.
Methods: Based on input from American patients with COPD and health professionals, the SGRQ was translated into American English (SGRQ-A) and then translated back to British English. For SGRQ-A reliability and validity studies, patients were asked to report symptoms experienced over 1 year (reporting period in the original SGRQ) and 1 month (modification made to SGRQ-A). We evaluated 102 patients with COPD (50% female; mean age, 68 years; mean forced expiratory volume in 1 second [FEV1], 1.01 L) at an administrative session before and after completion of a pulmonary rehabilitation program. The SGRQ-A, Chronic Respiratory Disease Questionnaire (CRQ), 36-Item Short Form Health Survey (SF-36), 6-minute walk (6MW), Medical Research Council (MRC) Dyspnea scale, and pulmonary function tests (FEV1 and % predicted FEV1) were used in the assessment battery.
Results: The SGRQ-A showed good agreement with the original SGRQ when translated back to British English. Internal reliability (Cronbach alpha) was > 0.70 for all SGRQ-A components except the 1-year symptom-reporting component. Test-retest intraclass correlations were 0.795 to 0.900. Construct validity was strengthened when all SGRQ-A components (except 1-year symptoms and most 1-month symptoms) correlated (P < or = 0.01) with the MRC Dyspnea scale, 6MW, all SF-36 concept scores, and 80% of CRQ domains (r = 0.30-0.72). Discriminate validity was demonstrated when all components of the SGRQ-A with the modified 1-month symptom-reporting period were shown to discriminate better between disease-severity groups (based on patient self-reports of disease severity) than did pulmonary function tests and the 6MW. Responsiveness of the SGRQ-A to change in health status was demonstrated when scores on the Symptoms-1 month and Total-1 month components detected significant improvements in patients' health status (P = 0.02 and P = 0.04, respectively).
Conclusion: The SGRQ-A with a modified 1-month symptom-reporting period demonstrated reliability and validity in this sample of patients with COPD. Key words: chronic obstructive pulmonary disease, St. George's Respiratory Questionnaire, American translation, reliability, validity, symptom recall.