title: Mortality prediction by surrogates of body composition: an examination of the obesity paradox in hemodialysis patients using composite ranking score analysis.
abstract: In hemodialysis patients, lower body mass index and weight loss have been associated with higher mortality rates, a phenomenon sometimes called the obesity paradox. This apparent paradox might be explained by loss of muscle mass. The authors thus examined the relation to mortality of changes in dry weight and changes in serum creatinine levels (a muscle-mass surrogate) in a cohort of 121,762 hemodialysis patients who were followed for up to 5 years (2001-2006). In addition to conventional regression analyses, the authors conducted a ranking analysis of joint effects in which the sums and differences of the percentiles of change for the 2 measures in each patient were used as the regressors. Concordant with previous body mass index observations, lower body mass, lower muscle mass, weight loss, and serum creatinine decline were associated with higher death rates. Among patients with a discordant change, persons whose weight declined but whose serum creatinine levels increased had lower death rates than did those whose weight increased but whose serum creatinine level declined. A decline in serum creatinine appeared to be a stronger predictor of mortality than did weight loss. Assuming residual selection bias and confounding were not large, the present results suggest that a considerable proportion of the obesity paradox in dialysis patients might be explained by the amount of decline in muscle mass.
authors.affiliation: David Geffen School of Medicine and UCLA School of Public Health, Harold Simmons Center for Chronic Disease Research and Epidemiology, Los Angeles, CA 90509-2910, USA. kamkal@ucla.edu
authors.forename: Kamyar
authors.initials: K
authors.lastname: Kalantar-Zadeh
authors.forename: Elani
authors.initials: E
authors.lastname: Streja
authors.forename: Miklos Z
authors.initials: MZ
authors.lastname: Molnar
authors.forename: Lilia R
authors.initials: LR
authors.lastname: Lukowsky
authors.forename: Mahesh
authors.initials: M
authors.lastname: Krishnan
authors.forename: Csaba P
authors.initials: CP
authors.lastname: Kovesdy
authors.forename: Sander
authors.initials: S
authors.lastname: Greenland
mesh_terms: D015415:Biomarkers / Q000097:blood; D015992:Body Mass Index; D003404:Creatinine / Q000097:blood*; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D007676:Kidney Failure, Chronic / Q000097:blood / Q000150:complications / Q000401:mortality* / Q000628:therapy; D008297:Male; D008875:Middle Aged; D018482:Muscle, Skeletal; D009765:Obesity / Q000097:blood / Q000150:complications; D016016:Proportional Hazards Models; D012044:Regression Analysis; D006435:Renal Dialysis; D015430:Weight Gain; D015431:Weight Loss
chemical_list: D015415:Biomarkers; D003404:Creatinine