title: Body mass index, age and in-hospital mortality: The NutritionDay multinational survey.
abstract: Several large and long-term prospective studies have assessed the association of body-mass index (BMI) next to age with the risk of death in the general population, but few have examined the association with in-hospital mortality. We investigated the association between BMI, age and in-hospital mortality.
  
  
  
  We used data collected during 9 consecutive one-day/year surveys (NutritionDay in hospital 2006-2014) conducted in non-critically ill adult patients from 2,183 hospitals across 51 nations from 4 continents. We examined the association of BMI and age with the risk of in-hospital (30-day) death using logistic regression analysis adjusted for multiple confounders.
  
  
  
  Crude mortality rates were 3.6% (95%CI, 3.5-3.7) and 2.1% (95%CI, 2.0-2.3) in the overall cohort (N = 97,344) and in those assessed within 72 hours since admission (N = 32,363), respectively. BMI and age were independently associated with the risk of death (no interaction observed), which decreased with BMI and increased with age. In the overall cohort, compared to normal weight status (BMI 18.5-24.9 kg/m2), death odds ratios for underweight (BMI < 18.5), overweight (BMI 25.0-29.9) and obesity (BMI ≥30) were 1.35 (95%CI, 1.20-1.53), 0.87 (95%CI, 0.77-0.97) and 0.73 (95%CI, 0.62-0.86), respectively. In patients assessed within 72 hours since admission, the associations were comparable: for underweight, 1.48 (95%CI, 1.11-1.96); for overweight, 0.80 (95%CI, 0.65-0.97); for obesity, 0.75 (95%CI, 0.58-0.96).
  
  
  
  In adult hospitalized patients BMI and age are independent predictors of in-hospital mortality. Low body weight is confirmed being a risk factor for death as in the general population, while overweight and obesity appear protective conditions. In the hospital setting, the use of normal weight status as reference low-risk category could also be challenged.
authors.affiliation: Nutrition and Dietetics Service, Fondazione IRCCS Policlinico San Matteo, Pavia, Italy. Electronic address: e.cereda@smatteo.pv.it.
authors.forename: Emanuele
authors.initials: E
authors.lastname: Cereda
authors.affiliation: Biometry and Statistics Service, Fondazione IRCCS Policlinico San Matteo, Pavia, Italy.
authors.forename: Catherine
authors.initials: C
authors.lastname: Klersy
authors.affiliation: Division Cardiac-, Thoracic-, Vascular Anaesthesia and Intensive Care, Medical University Vienna, Vienna, Austria.
authors.forename: Michael
authors.initials: M
authors.lastname: Hiesmayr
authors.affiliation: Division of Endocrinology and Metabolism, Department of Internal Medicine III, Medical University Vienna, Vienna, Austria.
authors.forename: Karin
authors.initials: K
authors.lastname: Schindler
authors.affiliation: Department of General Intensive Care and Institute for Nutrition Research, Rabin Medical Center, Beilinson Hospital, Sackler School of Medicine, Tel Aviv University, Petah Tikva, Israel.
authors.forename: Pierre
authors.initials: P
authors.lastname: Singer
authors.affiliation: Department of Clinical Medicine, "La Sapienza" University, Rome, Italy.
authors.forename: Alessandro
authors.initials: A
authors.lastname: Laviano
authors.affiliation: Nutrition and Dietetics Service, Fondazione IRCCS Policlinico San Matteo, Pavia, Italy.
authors.forename: Riccardo
authors.initials: R
authors.lastname: Caccialanza
mesh_terms: D000367:Age Factors; D000368:Aged; D015992:Body Mass Index; D016638:Critical Illness / Q000628:therapy; D005260:Female; D005500:Follow-Up Studies; D017052:Hospital Mortality; D006760:Hospitalization; D006801:Humans; D007391:International Cooperation; D016015:Logistic Models; D008297:Male; D008875:Middle Aged; D009749:Nutrition Surveys; D009752:Nutritional Status; D009765:Obesity; D050177:Overweight; D011446:Prospective Studies; D012307:Risk Factors; D013851:Thinness
keywords: Age; Body mass index; Hospital; Malnutrition; Mortality