Figure 4.

Association between asthma and severe exacerbations in mild-to-moderate COPD patients. Diamonds and whiskers show odds ratio and 95% CI values, respectively. Model 1 was adjusted for age, sex, and BMI; Model 2 was additionally adjusted for pulmonary-related variables generally considered to be important in severe exacerbations in COPD (smoking history and severity of airflow limitation); Model 3 additionally included extrapulmonary-related variables generally considered to be important in severe exacerbations in COPD or extrapulmonary-related variables with P<0.05 in the univariate analyses with considering multicollinearity (diabetes mellitus, cardiovascular disease [stroke, myocardial infarction, and angina pectoris], and quality of life); finally, Model 4 was additionally adjusted for use of inhalers with all of the above mentioned variables.

Abbreviations: BMI, body mass index; CI, confidence interval.