The effect of low body mass index on the development of chronic obstructive pulmonary disease and mortality

Background Sarcopenia may worsen disease progression and lead to poor outcomes in chronic obstructive pulmonary disease (COPD). Objectives We aimed to determine the effect of BMI on the development of COPD and mortality. Methods We enrolled 437 584 participants with COPD registered in the physical health check-up cohort database of the Korean National Health Interview Survey from 2002 to 2003, based on the ICD-10 code and prescribed medication. BMI (kg m(-2)) classified them to five groups (low BMI < 18.5, normal BMI 18.5-23, overweight 23-25, obesity 25-30, severe obesity >= 30) at baseline. Results Participants in the low BMI group had a significantly higher rate of COPD development for 13 years (7.6%) than those in other groups (3.4-4.1%, P < 0.0001). Amongst never or light smokers, COPD development in the low BMI group (5.6-6.7%) was significantly higher than that in other groups (2.8-4.7%). Similarly, amongst participants with a smoking history of >= 30 years, COPD development in the low BMI group (20.1%) was higher than those in other groups (8.4-12.4%). On multivariable analysis, normal or higher than normal body weight was significantly protective against the development of COPD (hazard ratio [HR], 0.609-0.739,) compared to low BMI. COPD-free-survival (HR, 0.491-0.622) and overall survival (HR, 0.440-0.585) were also better in them compared to those with low BMI (all P < 0.0001). Conclusions Low BMI is an important risk factor for COPD development and mortality. Maintaining adequate body weight may reduce the risk for COPD development and mortality.