The impact of body mass index (BMI) and body weight on hospitalization rates in haemodialysis patients is unknown. This study hypothesizes that being either underweight or obese is associated with a higher hospitalization rate. Observational study of 6296 European haemodialysis patients with prospective data collection and follow-up every six months for three years (COSMOS study). The risk of being hospitalized was estimated by a time-dependent Cox regression model and the annual risk (incidence rate ratios, IRR) by Poisson regression. We considered weight loss, weight gain and stable weight. Weight change analyses were also performed after patient stratification according to their baseline BMI. A total of 3096 patients were hospitalized at least once with 9731 hospitalizations in total. The hospitalization incidence (fully adjusted IRR 1.28, 95% CI [1.18-1.39]) was higher among underweight patients (BMI <20kg/m2) than patients of normal weight (BMI 20-25kg/m2), while the incidence of overweight (0.88 [0.83-0.93]) and obese patients (≥30kg/m2, 0.85 [0.79-0.92]) was lower. Weight gain was associated with a reduced risk of hospitalization. Conversely, weight loss was associated with a higher hospitalization rate, particularly in underweight patients (IRR 2.85 [2.33-3.47]). Underweight haemodialysis patients were at increased risk of hospitalization, while overweight and obese patients were less likely to be hospitalized. Short-term weight loss in underweight individuals was associated with a strikingly high hospitalization rate.

• MeSH
• Renal Dialysis * MeSH
• Risk Assessment MeSH
• Hospitalization statistics & numerical data   MeSH
• Thinness epidemiology   MeSH
• Body Mass Index * MeSH
• Middle Aged MeSH
• Humans MeSH
• Obesity epidemiology   MeSH
• Prospective Studies MeSH
• Aged MeSH
• Body Weight * MeSH
• Check Tag
• Middle Aged MeSH
• Humans MeSH
• Male MeSH
• Aged MeSH
• Female MeSH
• Publication type
• Journal Article MeSH
• Observational Study MeSH
• Research Support, Non-U.S. Gov't MeSH