Correlation of severity of chronic obstructive pulmonary disease with health-related quality of life and six-minute walk test in a rural hospital of central India

BACKGROUND: Chronic obstructive pulmonary disease (COPD) patients experience a progressive deterioration and disability leading to worsening of their health-related quality of life (HRQoL) and functional exercise capacity. We performed this study to identify the correlation of HRQoL assessed by St George's Respiratory Questionnaire (SGRQ) and the functional exercise capacity assessed by the six-minute walk test (6MWT) with severity of COPD defined by the Global Initiative for Chronic Obstructive Lung Disease (GOLD) criteria among spirometry-confirmed COPD patients, admitted in a tertiary care rural hospital. MATERIALS AND METHODS: The study included 129 spirometry-confirmed COPD patients defined by the GOLD criteria from a tertiary care hospital in central India. They underwent HRQoL measurement using the disease-specific (SGRQ). Functional exercise capacity was measured by 6MWT, as per the American Thoracic Society (ATS) guidelines. STATISTICAL ANALYSIS: We analyzed the various SGRQ scores and six-minute walk distance (6MWD) percentage predicted with various stages of COPD using the Student's t-test. The Pearson's correlation coefficient (r) was used to assess the relationships between various SGRQ scores and 6MWD with FEV(1) % predicted. RESULTS: We found that COPD patients with GOLD III and IV, but not GOLD II, had significantly poor HRQoL measured by SGRQ, as compared to patients with mild COPD (GOLD I). An inverse linear relation was found between 6MWD and the severity of COPD. Correlation of FEV(1) % predicted with various SGRQ scores varied from - 0.40 to - 0.53, with a maximum correlation of FEV(1) % predicted with an SGRQ symptom score (- 0.53) and SGRQ total score (- 0.50). A strong positive correlation was found between 6MWD and FEV(1) % predicted (0.57). CONCLUSIONS: Staging COPD according to the GOLD guidelines does correspond to important differences in the HRQoL of COPD patients having severe disease, but not for mild disease, whereas, the functional exercise capacity of COPD patients deteriorates in a linear fashion with the severity of disease assessed by the GOLD staging criteria.