C.W.OEI1, H.L.HTUN1, A.L.LI2, J.A.ABISHEGANADEN1, H.XU1, W.Y.LIM1
Tan Tock Seng Hospital1, MOH Holdings Pte Ltd (MOHH)2
Obesity is associated with mortality in the general population. However, some studies have found a lower risk of mortality in overweight/obese patients with chronic medical conditions (the “obesity paradox”). In this study, we investigate the relationship between body weight and mortality among patients with Chronic Obstructive Pulmonary Disease (COPD) admitted to an acute care tertiary hospital in Singapore.
We conducted a retrospective hospital-based cohort study between 2011-2018 among COPD patients identified through (i) primary discharge diagnosis, and (ii) lung function assessment by spirometry (pre- or post-bronchodilator FEV1/FVC<0.7 was defined as COPD). Body weight was determined by body mass index (BMI) measured within 6-months from admission. Mortality was ascertained from data collected by the Registry of Births and Deaths. Cox proportional hazard regression was used to estimate hazard ratio (HR) and 95% confidence interval (CI).
There were 1,577 COPD patients in this cohort, of whom 963 were confirmed by spirometry. At the end of follow-up, there were 669 deaths. Compared to patients with a BMI of 23.0-27.5kg/m2, <18.5kg/m2 and 18.5-22.9kg/m2 were associated with a significantly increased risk of all-cause (adjusted HR:2.71, 95%CI:2.18-3.38, HR:1.53, 95%CI:1.24-1.89, respectively) and respiratory-related mortality (HR:3.61, 95%CI:2.37-5.49, HR:1.84, 95%CI:1.22-2.79, respectively). No significant association was found in overweight (27.5-32.4kg/m2) and obese (≥32.5kg/m2) patients. Similar results were observed when we restricted the study to COPD patients confirmed by spirometry.
This study underlines a higher risk of mortality in underweight COPD patients. Improving nutritional status in such patients could be explored as a possible intervention.