ORGINAL ARTICLEIncreased length of hospital stay in underweight and overweight patients at hospital admission: a controlled population study
Introduction
Some degree of malnutrition has been reported in 30–50% of hospitalized patients.1 Malnutrition is associated with increased morbidity2 and complications, and leads to increased length of hospital stay (LOS), therapeutic hospital and rehabilitation cost.3
Assessment tools for the evaluation of nutritional status vary in their ability to predict LOS and morbidity. For example, increased risk of complications4 and a significant association between LOS and severely depleted nutritional status by Subjective Global Assessment (SGA) questionnaire have been previously determined.5 However, SGA does not determine the body compartments, i.e. fat-free mass and body fat mass, especially in overweight and obese subjects.
In epidemiological studies both low and high body mass index (BMI) have been associated with increased morbidity.6, 7, 8, 9 BMI has been used to estimate an excess or deficit in body weight, but is an imprecise measurement of fatness.10, 11 The differences in fat-free mass or fat mass in older compared to younger subjects may be due to shorter height of older subjects or due to changes in body composition. The use of fat-free mass index (FFMI) and fat mass index (FMI), similar to BMI (weight/height2 or kg/m2) permits comparison of subjects with different height.12
Body composition varies with age and disease and may affect patient outcome. We previously found that patients admitted to hospital had higher prevalence of falling below the 10th percentile for fat-free mass or above the 90th percentile for fat mass.13 Fat-free mass was also lower and % fat mass was higher in acute and chronically ill patients than in healthy controls.14 We further found that patients classified as severely depleted by Subjective Global Assessment were fat-free mass depleted.15
Schols et al.16 found that depletion of muscle mass, reflected by fat-free mass, could occur in patients who maintained their weight, and that fat-free mass depletion contributed to impaired functional status. Thus low fat-free mass may be an independent risk factor that impacts patient outcome. Indeed, Pichard et al.17 recently found a significant association between low FFMI and LOS at hospital admission. No association was found between high FMI and LOS in these patients with BMI in the normal range (mean 23.4±4.2 kg/m2). The current study extends our previous findings by evaluating patients in two European countries and by determining FMI in these populations. The study also compares patients at hospital admission to age- and height-matched healthy volunteers to determine if fat-free mass and body fat differences exist between patients and healthy volunteers.
Although low fat-free mass and high fat mass have been associated with increased morbidity and mortality, no previous studies have shown that high fat is associated with increased LOS. The purpose of this controlled population study (1707 patients, 1707 volunteers) was to evaluate the association between low FFMI and high FMI and LOS in patients at hospital admission.
Section snippets
Patients
In Geneva, all adult patients admitted to the hospital admission center for medical or surgical reasons and subsequently hospitalized were eligible for inclusion. Every 10th patient who met entry criteria was included in the study during a 3 months period. In Berlin, data were collected in the University Hospital Charité (Departments of Internal Medicine, Urology and General Surgery) and in the Community Hospital Krankenhaus Zehlendorf (Departments of Internal Medicine and General Surgery).
Results
The anthropometric characteristics of the volunteers and Geneva and Berlin patients are shown in Table 1. Table 2 shows the percentage of patients admitted to the different speciality services (i.e. gastroenterology, endocrinology, etc.) by LOS category. Only 0.5% of patients were hospitalized longer than 60 days and 2.2% 30–60 days.
The body composition parameters are shown by LOS category in Table 3. FFMI (Table 3) was significantly lower in male and female patients (except women hospitalized
Discussion
Although previous studies8, 26 have shown an association between obesity and mortality in the ICU and high BMI and LOS,9 this study, for the first time, demonstrates a clear association between high body fat and increased LOS in the general hospital population. Our study also confirms that longer LOS is associated with reduced lean tissue (low FFMI). The current study shows that both depletion of lean tissue and excess of fat mass negatively affect the LOS. Finally, we found that excess fat
Conclusion
Higher fat mass (FMI) and lower lean mass (FFMI) were found in patients at hospital admission than in sex- and age-matched healthy volunteers. For the first time, high FMI is also shown to be associated with increased LOS. Thus, the current study shows that depletion of both lean tissue and an excess of fat mass negatively affect the LOS. Finally, we found that excess fat mass reduces the sensitivity of BMI to detect nutritional depletion.
Acknowledgements
We thank the Foundation Nutrition 2000Plus for financial support. M. Pirlich was supported by the Else Kröner-Fresenius-Stiftung.
We are indebted to the staff involved in the patient admission procedure for their collaboration during data collection. We thank Heinrich J. Luebke, Martin Kemps, Niklas Luhmann, and Natalie Minko for data collection in Berlin. We thank P. Guerini for retrieving the LOS data of Geneva patients. We thank Alfred Morabia for statistical advice and critical discussion of
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