Decreased Risk of COPD Exacerbations in Obese Patients

Survival in chronic obstructive pulmonary disease (COPD) is enhanced in obese patients, which is called the obesity paradox. Despite some theories, the precise mechanism remains unclear. Since COPD exacerbations play a major role in COPD survival, this study aimed to stratify patients into BMI classes and investigate exacerbation frequency, time to readmission and survival in patients hospitalized with a COPD exacerbation. Therefore, patients hospitalized with an exacerbation of COPD were categorized into BMI groups using cut-offs <18.5, 25, 30 and ≥35 kg/m² for underweight, normal, overweight, moderately obese and severely obese groups and followed for five years. A total of 604 COPD patients was included. In comparison to normal weight patients, the 5-year exacerbation frequency was significantly decreased by 34-40% in obese patients depending on the BMI group (1.83 ± 1.60 per year in the normal weight group; overweight 1.60 ± 1.41; moderately obese 1.20 ± 1.18; severely obese 1.09 ± 1.13 per year; and 1.59 ± 1.30 in the underweight group). The time to readmission was up to 1.7 times longer for moderately obese patients compared to normal weight patients (954 ± 734 versus 564 ± 660 days). The data were supported by enhanced survival in obese patients and a regression analysis showing that both time to readmission and survival were associated with BMI independent of other possible confounders. In conclusion, this study shows a 'dose dependent' reduced exacerbation frequency and an increased time to readmission in obese patients admitted to the hospital with an exacerbation of COPD.