S1461 Investigating the Obesity Paradox in Hospitalized Patients With Chronic Obstructive Lung Disease Exacerbation in the United States

Abstract

Introduction: Obesity is a public health concern that is common among individuals with chronic obstructive pulmonary disease (COPD) and is associated with increased dyspnea and poor quality of life. Despite these negative associations, however, evidence suggests that obese patients with COPD have lower mortality than underweight COPD patients. This “obesity paradox” has been studied in long-term outcomes of COPD, but studies evaluating the effect of obesity on in-hospital outcomes of COPD exacerbation are few. Herein we evaluate the obesity paradox in hospitalized patients with COPD exacerbation using the National Inpatient Sample (NIS) database. Methods: A cohort study was conducted using NIS data from 2016 to 2019. Adult hospitalizations with an admitting diagnosis of COPD exacerbation and a documented body mass index (BMI) were included in the study. Patients were stratified by BMI as underweight, normal weight, overweight, class 1 obesity, class 2 obesity, and class 3 obesity. The primary outcome was in-hospital mortality. Secondary outcomes were invasive mechanical ventilation (IMV), non-invasive ventilation (NIV), and hospital length of stay (LOS). Multivariate analysis was used to adjust for outcomes. Covariates were selected using a univariate screen and literature review. Results: A total of 1,474,985 COPD exacerbation admissions were identified. In-hospital mortality was 6.1% in underweight, 5.8% in normal weight, 3.4% in overweight, and 1.9%, 1.7%, and 2.1% in class 1, class 2 and class 3 obesity groups, respectively (Table). Obesity class 1 and 2 had the lowest rates of IMV. Compared to normal weight patients, obese patients had greater rates of NIV, with class 3 obesity having the highest rate. LOS was lower in obese patients. After adjusting for potential confounders, both overweight and obesity were independently associated with higher rates of NIV and lower rates of IMV and mortality (Figure). Conclusion: This study demonstrates lower rates of mortality and IMV in obese patients admitted with COPD exacerbation. These findings support the existence of the obesity paradox in hospitalized patients with COPD exacerbation. However, several factors may confound the relation between obesity, COPD, and mortality, thus further prospective studies are needed to shed light on this complex phenomenon and its implications on healthcare.Figure 1.: Adjusted odds ratios for mortality, invasive mechanical ventilation, and non-invasive ventilation across the different ranges of BMI in reference to normal weight (BMI 20-24.9). Table 1. - In-hospital outcomes in COPD exacerbation hospitalizations across multiple BMI ranges Outcome Underweight Normal weight Overweight Obesity class1 Obesity class 2 Obesity class 3 Mortality 6.1% (5.9% - 6.3%) 5.8% (5.4% - 6.1%) 3.4% (3.2% - 3.7%) 1.9% (1.8% - 2.0%) 1.7% (1.6% - 1.9%) 2.1% (2.1% - 2.2%) Invasive ventilation 9.9% (9.7% - 10.2%) 10.7% (10.3% - 11.2%) 9.5% (9.1% - 10.0%) 7.5% (7.1% - 7.6%) 7.4% (7.1% - 7.6%) 9.8% (9.6% - 10.0%) Non-invasive ventilation 15.4% (15.0% - 15.8%) 14.8% (14.2% - 15.4%) 16.0% (15.3% - 16.6%) 16.2% (15.7% - 16.8%) 16.9% (16.4% - 17.4%) 20.8% (20.3% - 21.3%) > 5 days length of stay 44.7% (44.3% - 45.2%) 48.7% (47.9% - 49.6%) 42.5% (41.7% - 43.4%) 35.8% (35.3% - 36.7%) 35.1% (34.6% - 35.6%) 38.9% (38.6% - 39.3%) Parenthetical ranges represent 95% confidence intervals.