title: Contrasting effects of preexisting hyperglycemia and higher body size on hospital mortality in critically ill patients: a prospective cohort study.
abstract: BACKGROUND
  Obesity and diabetes mellitus are well-defined risk factors for cardiovascular mortality. The impact of antecedent hyperglycemia and body size on mortality in critical ill patients in intensive care units (ICUs) may vary across their range of values. Therefore, we prospectively analyzed the relationship between in-hospital mortality and preexisting hyperglycemia and body size in critically ill ICU patients to understand how mortality varied among normal, overweight, and obese patients and those with low, intermediate, and high glycated hemoglobin (HbA1c) levels.
  
  
  METHODS
  Medical history, weight, height, physiologic variables, and HbA1c were obtained during the first 24 h for patients who were consecutively admitted to the high complexity ICU of Hospital de Clínicas de Porto Alegre, Brazil, from April to August 2011. The relationships between mortality and obesity and antecedent hyperglycemia were prospectively analyzed by cubic spline analysis and a Cox proportional hazards model.
  
  
  RESULTS
  The study comprised 199 patients. The overall hospital mortality rate was 43.2% during a median 16 (8-28) days of follow-up. There was a progressive risk of in-hospital mortality with higher HbA1c levels, with the relationship becoming significant at HbA1c >9.3% compared with lower levels (hazard ratio 1.74; 95% confidence interval with Bonferroni correction 1.49-2.80). In contrast, mean body mass index (BMI) was higher in survivors than in nonsurvivors (27.2 kg/m2 ± 7.3 vs. 24.7 kg/m2 ± 5.0 P = 0.031, respectively). Cubic spline analysis showed that these relationships differed nonlinearly through the spectrum of BMI values. In a Cox proportional hazards model adjusted for Acute Physiology and Chronic Health Evaluation II score and HbA1c, the risk of in-hospital mortality progressively decreased with increasing BMI (BMI <20 vs. 20-23.9 kg/m2, P = 0.032; BMI <20 vs. 24-34.9 kg/m2, P = 0.010; BMI <20 vs. ≥35 kg/m2, P = 0.032).
  
  
  CONCLUSIONS
  Our findings suggest that significant hyperglycemia prior to ICU admission is a risk factor for in-hospital mortality. Conversely, increasing BMI may confer an advantageous effect against mortality in critical illness independently of previous glycemic control.
authors.affiliation: Intensive Care Unit, Division of Endocrinology, Hospital de Clínicas de Porto Alegre, Federal University of Rio Grande do Sul, Porto Alegre, Brazil. marivv@terra.com.br.
authors.forename: Marina Verçoza
authors.initials: MV
authors.lastname: Viana
authors.forename: Rafael Barberena
authors.initials: RB
authors.lastname: Moraes
authors.forename: Amanda Rodrigues
authors.initials: AR
authors.lastname: Fabbrin
authors.forename: Manoella Freitas
authors.initials: MF
authors.lastname: Santos
authors.forename: Vanessa Bielefeldt Leotti
authors.initials: VB
authors.lastname: Torman
authors.forename: Silvia Regina
authors.initials: SR
authors.lastname: Vieira
authors.forename: Jorge Luiz
authors.initials: JL
authors.lastname: Gross
authors.forename: Luis Henrique
authors.initials: LH
authors.lastname: Canani
authors.forename: Fernando
authors.initials: F
authors.lastname: Gerchman
mesh_terms: D001786:Blood Glucose / Q000032:analysis; D015992:Body Mass Index; D049628:Body Size; D001938:Brazil; D016638:Critical Illness / Q000401:mortality*; D005260:Female; D005500:Follow-Up Studies; D017052:Hospital Mortality / Q000639:trends*; D006760:Hospitalization / Q000706:statistics & numerical data*; D006801:Humans; D006943:Hyperglycemia / Q000503:physiopathology*; D007362:Intensive Care Units; D008297:Male; D008875:Middle Aged; D009765:Obesity / Q000503:physiopathology*; D011379:Prognosis; D011446:Prospective Studies; D012307:Risk Factors
chemical_list: D001786:Blood Glucose