Contrasting effects of preexisting hyperglycemia and higher body size on hospital mortality in critically ill patients: a prospective cohort study

Abstract

BackgroundObesity 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.MethodsMedical 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.ResultsThe 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).ConclusionsOur 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.

Relationship between glycated hemoglobin, Intensive Care Unit admission blood sugar and glucose control with ICU mortality in critically ill patients

“…The weak correlation between HbA 1 c and BMI suggests an independent effect of these metabolic parameters as prognostic factors in critically ill patients. [ 31 ] Kompoti et al . showed that a cutoff of 6.5% for HA1c could predicte higher ICU mortality in patients without prior history of diabetes; but, in patients with prior history of diabetes a cutoff of 7 for HbA1c had no association with ICU mortality.…”

ESPEN guideline on clinical nutrition in the intensive care unit

“…Additional metabolic derangements such as decreased glucose tolerance, altered lipid metabolism, lack of micronutrients and decreased gut motility will need specific attention [340]. Recommendations on early EN, gastrointestinal tolerance and progressive increase in nutrition over several days apply similarly to overweight and obese patients as to all other ICU patients.…”

Nutritional therapy and outcomes in underweight critically ill patients

“…To identify malnourished patients, we used a BMI lower than 20 kg/m 2 , which has been associated with poorer survival rates in critically ill patients than higher BMIs [5]. In addition, similar definitions and cut-off points were described in other studies [29,40].…”

“…Malnutrition is robustly associated with death in critically ill patients [4]. A body mass index (BMI) lower than 20 kg/m 2 has been associated with poorer survival in critically ill patients, probably because of its role as a marker of nutritional status [5,6].…”