Body mass index among patient with chronic obstructive pulmonary diseases.

Body mass index (BMI) is one of the important parameter to assess functional status of patients with Chronic Obstructive Pulmonary Disease (COPD). The aim of present study was to assess the prevalence of underweight among clinically stable COPD patients and relationship of BMI with increasing severity of COPD. COPD was defined as a subject who had post-bronchodilator FEV1/FVC < lower limit of normal, age more than 40 years and either current or ex smoker. Spirometry data of 7412 subjects were retrospectively analyzed and 1269 COPD patients and 1202 bronchial asthma patients were identified. The severity of airflow obstruction was classified as per GOLD guideline. The BMI of each patient was calculated from weight and height. The BMI of COPD patients were compared with bronchial asthma. The average BMI of COPD patients and bronchial asthma patients were 20.2 +/- 4.3 kg/m2 and 23.2 +/- 5.4 kg/m2 respectively. Overall, 38% COPD patients were underweight (BMI < 18.5 kg/m2) and irrespective of severity of the disease, proportion of underweight COPD patient was significantly more as compared to bronchial asthma patients (P < 0.001). The mean BMI also reduces significantly with progression of COPD severity.