Title:
The association between body mass index and all-cause mortality in Dutch incident hemodialysis patients.

R. de Mutsert¹ ;R. de Mutsert¹ ;R. de Mutsert¹ ;R. de Mutsert² ;R. de Mutsert³ ;R. de Mutsert¹

The Netherlands' ne '' The Netherlands' ne '' The Netherlands' ne ''

E-mail address corresponding author:
r.de_mutsert@lumc.nl

Background:
Obesity is associated with increased mortality in the general population. However, the reverse association has been found in US prevalent hemodialysis (HD) patients. The objective of this study was to investigate the association between body mass index (BMI) and all-cause mortality in a cohort of Dutch incident HD patients and to compare the results with the Dutch general population.

Methods:
NECOSAD is a prospective multi-centre cohort study in 38 out of 50 Dutch dialysis centres. All incident dialysis patients of 18 years or older have been included in this cohort between 1997 and 2004. Demographic and clinical data were collected at baseline, 3 and 6 months after the start of dialysis and subsequently every 6 months of follow-up. Patients were followed until date of death or censored at the date of transplantation, withdrawal or at the end of the study (01-01-2005). The HD patients were categorised based on their BMI at the start of dialysis. Hazard ratios (HR) for 7-years mortality were calculated using Cox regression with a BMI of 22.5-25 kg/m2 as the reference category. Analyses were performed separately for men and women, and adjusted for age and comorbidity. Results were compared to data from the Dutch general population [Seidell, Arch Intern Med, 1996].

Results:
In total 1216 HD patients were included with a mean age of 64 ± 14 years and a mean BMI of 25.2 ± 4.7 kg/m2, 713 men and 503 women. The 2-years mortality was 17%, the 7-years mortality was 53%. There was no association between BMI and mortality in female HD patients, which is also observed in Dutch women from the general population. Compared to the reference category, male HD patients with a BMI <20 kg/m2 had an increased mortality risk (HR: 2.43, 95%-CI: 1.59-3.73). Compared to the Dutch general population, male HD patients showed a similar mortality risk pattern for all BMI categories <30 kg/m2. In contrast to an increased mortality risk for obese men in the general population, the mortality risk for male HD patients with a BMI ≥30 kg/m2 did not differ from the reference category (HR: 1.04, 95%-CI: 0.62-1.74).

Conclusion:
No survival advantage was found in obese HD patients. Hence, the association between BMI and all-cause mortality in Dutch incident HD patients showed no reverse epidemiology.

Subject:
Hemodialysis

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