Association between body mass index and in-hospital outcomes: Analysis of the nationwide inpatient database

IMPORTANCE: Over one-third of American adults (36%) are obese and more than two-thirds (69%) are overweight. The impact of obesity on hospitalization outcomes is not well understood. OBJECTIVE: To examine the association between body mass index (BMI) and overall, cancer, chronic obstructive pulmonary disease (COPD), asthma, and cardiovascular disease (CVD)-specific in-hospital mortality; postsurgical complications; and hospital length of stay (LOS). DESIGN: Cross-sectional study. SETTING: Representative sample of US hospitals included in the Health Cost and Utilization Project Nationwide Inpatient Sample database. PARTICIPANTS: We obtained data for patients admitted with a primary diagnosis of cancer, COPD, asthma, and CVD. MAIN OUTCOME: In-hospital mortality, postsurgical complications, and hospital LOS. RESULTS: A total of 800,417 patients were included in this analysis. A higher proportion of Blacks (26.8%; 12.5%) and Whites (23.3%; 8.7%) had BMI of 40 to 49.9 and ≥50, respectively, compared with Hispanics (20.4%; 7.3%). Compared with normal BMI patients, the odds of in-hospital mortality increased 3.6-fold (odds ratio [OR] 3.62, 95% confidence interval [CI]: 3.37–3.89) for preobese patients, 6.5-fold (OR: 6.52, 95% CI: 5.79–7.34) for patients with BMI: 30 to 31.9, 7.5-fold (OR: 7.57, 95% CI: 6.67–8.59) for patients with BMI: 34 to 35.9, and 1.6- fold (OR: 1.77, 95% CI: 1.56–1.79) for patients with BMI ≥ 50. Compared with normal BMI patients, preobese and overweight patients had shorter hospital stays (β preobese: −1.58, 95% CI: −1.63, −1.52); however, no clear trends were observed for postsurgical complications. CONCLUSIONS: The majority of hospitalized patients in this analysis had a BMI > 30, and higher BMI was associated with increased risk of mortality and longer hospital stay.