Comorbidity in chronic obstructive pulmonary disease (COPD): Data from the fourth Korean National Health and Nutrition Examination Survey (KNHANES IV)

Abstract

Introduction: Many comorbidities frequently coexist with chronic obstructive pulmonary disease (COPD) and they could influence on poor prognosis. We tried to determine which comorbidities frequently coexist in individuals with COPD using population based nationwide survey.

Method: We used data obtained in the first (2007) and second year (2008) of the Fourth Korean National Health and Nutrition Examination Survey (KNHANES IV) and included participants aged ≥40 years. Subjects with FEV₁/FVC<0.7 was defined as individuals with COPD. Participants with history of asthma, pulmonary tuberculosis and bronchiectasis were excluded.

Result: Baseline characteristics were not significantly different between COPD group (n=357) and control group (n=357) except spirometric findings. COPD group was associated with increased risk of low BMI (<18.5 Kg/m²) (OR 3.53, 95% CI 1.29-9.68; p=0.014) and associated with decreased risk of hypertension (OR 0.73, 95% CI 0.54-0.99; p=0.042) and hypercholesterolemia (OR 0.59, 95% CI 0.37-0.93; p=0.022). The incidence of low BMI uniquely increased with the severity of airflow obstruction (1.4% in control subjects, 3.6% in GOLD stage I, 4.5% in GOLD stage II and 30% in GOLD stage III+; p<0.0001). However, the incidence of hypertension and hypercholesterolemia did not.

Conclusion: Incidence of low BMI uniquely increased with the severity of airflow limitation. However, more study is needed to confirm whether low BMI is the cause of COPD or the result of COPD.