Body Mass Index and Mortality in Subjects With ARDS: Post-hoc Analysis of the OSCILLATE Trial
Tlayjeh H1, Arabi YM2, Ferguson ND3, Zhou Q4, Lamontagne F5, Arroliga A6, Danesh V7, Dominguez-Cherit G8, Jimenez E6, Mullaly A6, Staub B9, Meade MO4; Canadian Critical Care Trials Group.
1 Intensive Care Department, King Saud bin Abdulaziz University for Health Sciences, King Abdullah International Medical Research Center, Riyadh, Saudi Arabia.
2 Intensive Care Department, King Saud bin Abdulaziz University for Health Sciences, King Abdullah International Medical Research Center, Riyadh, Saudi Arabia. email@example.com.
3 Interdepartmental Division of Critical Care Medicine, Departments of Medicine and Physiology, Institute for Health Policy, Management and Evaluation, Division of Respirology, University of Toronto, Toronto, Canada.
4 Department of Health Research Methods, Evaluation and Impact, McMaster University, Hamilton, Canada.
5 Université de Sherbrooke, Sherbrooke, Canada and Centre de recherche du CHU de Sherbrooke, Sherbrooke, Canada.
6 Department of Medicine, Baylor Scott and White Health, Temple, Texas.
7 School of Nursing, University of Texas at Austin, Texas.
8 Division of Pulmonary, Anesthesia and Critical Care Medicine, The National Institute of Medical Sciences and Nutrition, Salvador Zubirán, Tlalpan, Mexico.
9 Department of Anesthesiology, University of Pittsburgh Medical Center, Pittsburgh, Pennsylvania.
Year of Publication:
Studies on the association of obesity with mortality in subjects with ARDS have yielded inconsistent results.
In a sub-analysis of the Oscillation for ARDS Treated Early (OSCILLATE) randomized controlled trial, 451 subjects were divided into 5 strata based on their body mass index (BMI) using the World Health Organization definitions: underweight < 18.5 kg/m2; normal weight 18.5-24.99 kg/m2; overweight 25-29.99 kg/m2; obese 30-39.99 kg/m2; severely obese > 40 kg/m2. The primary outcome was all-cause hospital mortality across BMI strata for all subjects and for the 2 study arms (high-frequency oscillatory ventilation [HFOV] vs conventional ventilation) separately using multivariable logistic regression adjusting for potential confounding variables.
Hospital mortality was not different across the BMI strata for all subjects (P = .86), for the HFOV arm (P = .94) or for the conventional ventilation arm (P = .59). After risk adjustment, BMI was not associated with increased risk for hospital mortality (odds ratio 1.01, 95% CI 0.97-1.04, P = .67), whereas HFOV was independently associated with increased mortality (odds ratio 1.74, 95% CI 1.11-2.72, P = .02) with no effect modification by BMI strata (for this interaction, P = .56). Although there was no difference in the use of rescue therapies or in the number of days on sedation or analgesia, higher daily doses of fentanyl and midazolam were administered as BMI increased.
There was no difference in adjusted hospital mortality across BMI strata in subjects with moderate to severe ARDS. Processes of care were not different across BMI strata except for higher daily doses of fentanyl as BMI increased. (ClinicalTrials.gov registration NCT0150640).