Association between quality of life as assessed by St. George's respiratory questionnaire (SGRQ), lung function indices and sputum inflammatory parameters in Indian COPD patients

COPD attributes significantly in quality of life. We aimed to investigate the association between quality of life as evaluated by the St. George's Respiratory Questionnaire (SGRQ), lung function and sputum inflammatory cells in smoker and non-smoker COPD (S-COPD vs NS- COPD) patients. Methods : 39 S-COPD and 47 NS-COPD patients were administered the SGRQ and underwent spirometry, bodyplethysmography, IOS and sputum induction. Using correlation matrices, we assessed the associations between total SGRQ scores and its various components with lung function indices and sputum inflammatory cell counts. Results : The total SGRQ score correlated significantly with RV [r2=0.253, p=0.02], IC /TLC [r2=-0.247, p=0.03], and FRC [r2=0.269, p=0.01], but not with any other spirometric or sputum inflammatory index. The symptoms score component of the SGRQ correlated significantly with total [r2=0.267, p=0.03] as well as sputum neutrophil [r2=0.251, p=0.04] counts. Activity limitation scores correlated with FRC [r2=0.268, p=0.01], RV [r2=0.263, p=0.02] and IC/TLC [r2=-0.294, p=0.01], while impact scores correlated with FRC [r2=0.239, p=0.03] and RV [r2=0.223, p=0.04]. None of the total as well as unit SGRQ scores correlated with any spirometric (FEV1, FVC, TLC, FEF25-75%), or IOS (R5Hz, R20Hz, R5-20Hz or AX) values. Conclusion : Quality of life scores in COPD patients correlated significantly with indices that demonstrate physiological air trapping while symptom scores correlated with sputum cellular inflammatory counts, while spirometry or IOS indices did not correlate with quality of life parameters in Indian COPD patients.