Study objectives: To verify whether and to what extent the body mass index, airflow obstruction, dyspnea, and exercise capacity (BODE) index correlates with a disease-specific index of health status in patients with COPD.
Design: Cross-sectional study.
Setting: University-affiliated hospital.
Patients: One hundred patients with stable COPD recruited from the outpatient clinic of a single institution.
Measurements: The BODE index was calculated for each patient using variables obtained within 2 weeks of enrollment. At enrollment, all patients completed the St George's Respiratory Questionnaire (SGRQ). The Kruskal-Wallis test was used to compare health status scores with clinical and functional categories of COPD. The Spearman correlation coefficient (r) was calculated to assess the association between health status scores and clinical or functional variables.
Results: Categorizing the BODE scores into 4 quartiles, we found that higher BODE quartiles were associated with higher (worse) SGRQ scores. The differences among the BODE quartiles in health status indexes were significant for total SGRQ as well as all 3 of the SGRQ subscales. In all sections of the SGRQ, scores were moderately to strongly associated with the BODE quartiles (r = 0.27-0.46). In contrast, the association between the SGRQ total, impacts, activity and Global Initiative for Chronic Obstructive Lung Disease (GOLD) stages were weaker (r = 0.27-0.28). There was no significant association between SGRQ symptoms and GOLD stages.
Conclusions: The BODE scoring system corresponds to important differences in health status of patients with COPD. This grading system is better correlated to the health status indexes of the SGRQ than the GOLD staging criteria.