Prognostic assessment in COPD: health related quality of life and the BODE index

Abstract

Rationale: COPD is a debilitating disease with increasing mortality worldwide. The BODE index evaluates disease severity and the St George's Respiratory Questionnaire (SGRQ) measures health status.

Objective: To identify the relationship between BODE index and the SGRQ and to test the predictive value of both tools against survival.

Methods: Open cohort study of 1398 COPD patients (85% male) followed for up to 10 years.

Measurements and main results: At the time of the inclusion, clinical data, forced spirometry and 6 min walking distance were determined and BODE index and SGRQ were calculated. Vital status and cause of death were documented at the end of follow-up.

Results: The cohort's mean of FEV1% predicted was 46 ± 18%, BODE index was 3.6 ± 2.5, and SGRQ% total score was 49 ± 20. The SGRQ scores increased progressively as severity of COPD increased by BODE quartiles. The correlation between SGRQ and BODE index was good (r = 0.58, p < 0.0001). Both tests correlated with COPD survival (BODE = -0.4 vs. SGRQ = -0.20, p < 0.0001). The area under the curve (AUC) for the BODE index was 0.77 vs. 0.66 for the SGRQ % total score (p < 0.001).

Conclusions: Health status as measured by SGRQ worsens with disease severity evaluated by the BODE index. Both tools predict mortality and provide complimentary information in the evaluation of patients with COPD.