Impact of BMI on exacerbation and medical care expenses in subjects with mild to moderate airflow obstruction

Abstract

Background and objective

The rate of obesity is increasing in Asia, but the clinical impact of body mass index (BMI) on the outcome of chronic obstructive pulmonary disease (COPD) remains unknown. We aimed to assess this impact while focusing on the risk of exacerbation, health-care utilization, and medical costs.

Methods

We examined 43,864 subjects registered in the Korean National Health and Nutrition Examination Survey (KNHANES) database from 2007 to 2012, and linked the data of COPD patients who had mild to moderate airflow obstruction (n = 1,320) to National Health Insurance (NHI) data. COPD was confirmed by spirometry. BMI was used to stratify patients into four categories: underweight (BMI <18.5 kg/m²), normal range (18.5–22.9 kg/m²), overweight (23–24.9 kg/m²), and obese (≥25 kg/m²).

Results

Of the 1,320 patients with COPD with mild to moderate airflow obstruction, 27.8% had a BMI ≥25 kg/m². Compared with normal-weight patients, obese patients tended to experience fewer exacerbations (incidence rate ratio [IRR] 0.88; 95% CI 0.77–0.99; P = 0.04), although this association was not significant in a multivariable analysis. COPD-related health-care utilization and medical expenses were higher among underweight patients than the other groups. After adjustment, the risk of COPD-related hospitalization was highest among underweight and higher among overweight patients vs normal-weight patients (adjusted IRRs: 7.12, 1.00, 1.26, and 1.02 for underweight, normal, overweight, and obese groups, respectively; P = 0.01).

Conclusion

Decreased weight tends to negatively influence prognosis of COPD with mild to moderate airflow obstruction, whereas higher BMI was not significantly related to worse outcomes.

Keywords:

• COPD
• obesity
• exacerbation
• health-care utilization
• medical expenses

Supplementary materials

Figure S1 Cumulative chronic obstructive pulmonary disease (COPD)-related medical costs per person-year stratified by body mass index (BMI).

Note: Medical costs are presented in US dollars (USD) with an exchange rate of 1 USD equal to 1,140 Korean won (exchange rate on May, 2017).

Table S1 Subgroup analysis of the risk of exacerbation according to the severity of airflow limitation

Table S2 Subgroup analysis of the risk of chronic obstructive pulmonary disease (COPD)-related health-care utilization during a 5-year period according to the forced expiratory volume in 1 s (FEV₁)

Disclosure

The authors report no conflicts of interest in this work.