Exploring the impact of number and type of comorbidities on the risk of severe COPD exacerbations in Korean Population: a Nationwide Cohort Study.

BACKGROUND It is difficult to assess the impact of multiple comorbidities on clinical outcomes in chronic obstructive pulmonary disease (COPD). In this study, we aimed to investigate exacerbation-associated comorbidities, determine whether the number of comorbidities is an independent risk factor for exacerbation, and identify other exacerbation-associated factors in a Korean COPD population using a nationwide population-based cohort. This study focused on severe exacerbations that required hospitalisation or emergency room visits. METHODS The National Health Insurance Service-National Sample Cohort, version 2.0, data sampled between 2002 and 2015 were analysed. Data from two years after the diagnosis of COPD were analysed for each participant (N = 12,554, entire cohort). Moreover, 42% of the participants underwent additional health examinations (N = 5306, health-screening cohort). Fifteen comorbidities that were previously reported as risk factors for exacerbations were examined. A logistic regression model was used to analyse association with exacerbations. RESULTS Asthma (1.57 [1.39-1.76] and 1.24 [1.06-1.44]), lung cancer (1.84 [1.30-2.59] and 2.28 [1.54-3.37]), and heart failure (1.39 [1.16-1.67] and 1.52 [1.18-1.97]) were associated with exacerbation in both cohorts (odds ratio [95% confidence interval] in the entire cohort and health-screening cohort, respectively). The number of comorbidities was an independent risk factor, and old age, male sex, low body mass index, and current smoking were also independent risk factors. High cholesterol levels and body mass index exerted protective effects against exacerbation. CONCLUSIONS The number of comorbidities, certain comorbidities such as asthma, lung cancer and heart failure, and low BMI were associated with an increased risk of severe exacerbation in COPD patients.