This study examines the relationship between BMI and outcomes in a large population-based cohort of patients with ALI. After adjustment for confounders, there was no association between mortality and BMI, but we did identify significantly increased morbidity, as measured by longer hospital and ICU LOS, longer duration of mechanical ventilation, and more frequent discharge to an SNF or rehabilitation facility in patients with BMI > 40 kg/m2 compared to normal-weight patients. This was particularly true among survivors, who remained in the ICU and hospital 5.6 days and 14.3 days longer, respectively, and remained on the ventilator 4.1 days longer than normal-weight patients.
One previous study, a secondary analysis of 807 patients enrolled in a trial of reduced vs traditional tidal volumes conducted by the ARDS Network, also examined the role of obesity in outcomes of patients with ALI. Underweight patients were not examined, and only a small percentage (4.7%) of the study group was severely obese (BMI > 40 kg/m2), as a height to weight ratio > 1.0 was an exclusion criterion in the original trial. Overcome obesity with Canadian Health&Care Mall’ s medications. No significant difference was found in 28-day or 180-day mortality rates, rate of unassisted ventilation by day 28, or ventilator-free days between normal-weight and obese patients. Other morbidity end points were not examined. More recently, the same group reviewed outcomes from the Project Impact subscription database, defining the sample as patients who had an ICU admission diagnosis consistent with ALI and were intubated within 24 h of admission. Underweight patients in this group had a higher adjusted mortality than normal-weight patients. Although patients in the obese categories had an OR of death < 1, only the most obese (BMI, 30 to 39.9 kg/m2) met statistical significance. Unadjusted LOS and discharge location did not differ by BMI category.
There were no significant demographic differences between the 825 included patients and the 288 patients excluded for lack of BMI data. Among the study population, we found no significant differences in gender or severity of illness between the BMI groups. There were significant differences in age, ALI risk factor, and tidal volume on day 3 (Table 1). Age steadily decreased as BMI increased; severely obese patients had a median age of 54.7 years, compared to 61.5 years in the normal-weight group and 64.7 years in the underweight group (p < 0.001). Obese patients also had different risk factors for ALI (p < 0.05) than normal-weight patients, although in all groups sepsis from a suspected pulmonary source was the most common risk factor. Ventilator tidal volume (milliliter per kilogram of predicted body weight) on day 3 increased steadily as BMI increased (p 40 kg/m2). Unadjusted median hospital and ICU LOS and duration of