The Impact Of Body Mass Index On Inpatient- Versus Outpatient-Treated Chronic Obstructive Pulmonary Disease Exacerbations

BACKGROUND: Increased body weight has been associated with worse prognoses for many chronic diseases; however, this relationship is less clear in patients with chronic obstructive pulmonary disease (COPD), with underweight patients experiencing higher morbidity than normal or overweight patients.OBJECTIVE: To assess the impact of body mass index (BMI) on the risk for COPD exacerbations.METHODS: The present study included 115 patients with stable COPD (53% women; mean [± SD] age 67±8 years). Height and weight were measured to calculate BMI. Patients were followed for a mean of 1.8±0.8 years to assess the prospective risk of inpatient-treated exacerbations and outpatient-treated exacerbations, all of which were verified by chart review.RESULTS: Cox regression models revealed that underweight patients were at greater risk for inhospital-treated exacerbations (RR 2.93 [95% CI 1.27 to 6.76) relative to normal weight patients. However, overweight (RR 0.59 [95% CI 0.33 to 1.57) and obese (RR 0.99 [95% CI 0.53 to 1.86]) patients did not differ from normal weight patients. All analyses were adjusted for age, sex, length of diagnosis, smoking pack-years, forced expiratory volume in 1 s, and time between recruitment and last exacerbation. BMI did not influence the risk of out-of-hospital exacerbations.CONCLUSIONS: The present study showed that underweight patients were at greater risk for inhospital exacerbations. However, BMI did not appear to be a risk factor for out-of-hospital exacerbations. This suggests that the BMI-exacerbation link may differ according to the nature of the exacerbation, the mechanisms for which are not yet known.