Epidemiology and OutcomesAssociation between Body Mass Index and Mortality Is Similar in the Hemodialysis Population and the General Population at High Age and Equal Duration of Follow-Upde Mutsert, Rene[Combining Acute Accent]e*; Snijder, Marieke B.† , ‡; van der Sman-de Beer, Femke*; Seidell, Jacob C.†; Boeschoten, Elisabeth W.§; Krediet, Raymond T.‖; Dekker, Jacqueline M.‡; Vandenbroucke, Jan P.*; Dekker, Friedo W.* for the Netherlands Cooperative Study on the Adequacy of Dialysis-2 (NECOSAD) Study Group Author Information *Department of Clinical Epidemiology, Leiden University Medical Center, Leiden, †Institute of Health Sciences, Department of Nutrition and Health, Vry[Combining Diaeresis]e Universiteit Medical Center, ‡EMGO Institute, Vry[Combining Diaeresis]e Universiteit Medical Center, and ‖Department of Nephrology, Academic Medical Center, Amsterdam, and §Hans Mak Institute, Naarden, The Netherlands Address correspondence to: Rene[Combining Acute Accent]e de Mutsert, MSc, Leiden University Medical Center, Department of Clinical Epidemiology, PO Box 9600, 2300 RC Leiden, The Netherlands. Phone: +31-71-526-6534; Fax: +31-71-526-6994; E-mail: [email protected] Accepted December 29, 2006 Received September 25, 2006 Journal of the American Society of Nephrology 18(3):p 967-974, March 2007. | DOI: 10.1681/ASN.2006091050 Buy Metrics Abstract The association of body mass index (BMI) with mortality in hemodialysis patients has been found to be reversed in comparison with the general population. This study examined the association of BMI with mortality in the hemodialysis population and the general population when age and time of follow-up were made strictly comparable. Hemodialysis patients who were aged 50 to 75 yr at the start of follow-up were selected from the Netherlands Cooperative Study on the Adequacy of Dialysis-2 (NECOSAD), a prospective cohort study in incident dialysis patients in the Netherlands (n = 722; age 66 ± 7 yr; BMI 25.3 ± 4.5 kg/m2), and compared with adults who were aged 50 to 75 yr and included in the Hoorn Study, a population-based prospective cohort study in the same country (n = 2436; age 62 ± 7 yr; BMI 26.5 ± 3.6 kg/m2). In both populations, 2- and 7-yr standardized mortality rates were calculated for categories of BMI. Adjusted hazard ratios (HR) of BMI categories were calculated with a BMI of 22.5 to 25 kg/m2 as the reference category within each population. In 7 yr of follow-up, standardized mortality rates were approximately 10 times higher in the hemodialysis population than those in the general population. Compared with the reference category, the HR of BMI <18.5 kg/m2 was 2.0 (95% confidence interval [CI]1.2 to 3.4) in the hemodialysis population and 2.3 (95% CI 0.7 to 7.5) in the general population. Obesity (BMI ≥30 kg/m2) was associated with a HR of 1.2 (95% CI 0.8 to 1.7) in the hemodialysis population and 1.3 (95% CI 0.9 to 2.0) in the general population. In conclusion, a hemodialysis population and a general population with comparable age and equal duration of follow-up showed similar mortality risk patterns associated with BMI. This suggests that there is no reverse epidemiology of BMI and mortality in hemodialysis patients. The clinical implication of this study is that to improve survival in the hemodialysis population, more attention should be paid to patients who are underweight instead of overweight. Copyright © 2007 The Authors. Published by Wolters Kluwer Health, Inc. All rights reserved.