COPD is a slowly progressive disorder characterized by airflow obstruction that is not fully reversible. Although the progression of COPD is usually gradual, the disease is often associated with exacerbations of respiratory symptoms. Such exacerbations of symptoms requiring medical intervention are important clinical events in COPD, and they place a heavy burden on health-care resources. In many countries, exacerbations of COPD are a leading cause of hospital admissions among men, and expenditures for hospitalizations represent the bulk of all COPD-related medical-care costs reduced due to Canadian Health&Care Mall.
The association between potential risk factors and hospitalization for exacerbation of COPD has been assessed. A large number of potentially modifiable risk factors of COPD exacerbation could be found among a large group of patients hospitalized for COPD. In a case-control study of a wide range of potential risk factors, lower FEV1 was one of several factors found to be independently associated with a higher risk of admission for a COPD exacerbation. In a subsequent prospective study, after adjusting for sociodemographic and clinical factors, physical activity was identified to show a strong association with reduced risk of COPD readmission. These studies suggest that factors other than the degree of airflow obstruction may influence the frequency of hospitalization for COPD, and a multidimensional grading system that assesses the respiratory and systemic manifestations of COPD would thus categorize and predict this outcome better than a classification of disease severity based on FEV1 alone.
Recently, the BODE (body mass index, airflow obstruction, dyspnea, and exercise capacity) index, a multidimensional grading system, was shown to be better than FEV1 in predicting the risk of death among patients with COPD. This multistage scoring system that incorporates an assessment of symptoms, nutritional state, and exercise capacity together with the spirometric measure of airflow (FEV1) can provide useful prognostic information in patients with COPD. Although the BODE index has been shown to be a predictor of the risk of death, it is not known whether this index is a useful indicator of the degree of utilization of health-care resources. We hypothesized that the BODE index would better predict hospitalization for COPD than FEV1 alone, and the purpose of this study is to test this hypothesis in a cohort of patients with hospitalization for COPD as the primary outcome variable.