The case-mix-adjusted analysis included the following variables: age, sex, race, ethnicity, blood pressure, body mass index, standardized mortality rate, vascular access, history of diabetes, and congestive heart failure. The multivariable-adjusted analysis included the case-mix variables plus phosphate, calcium, log parathyroid hormone, albumin, creatinine, and ferritin. Quartile 1 is the reference group in all models (Quartile 1, < 1090 RU/ml; Quartile 2, 1090–1750 RU/ml; Quartile 3, 1751–4010 RU/ml; Quartile 4, > 4010 RU/ml). Vertical lines represent 95% confidence intervals. This figure is reproduced from Gutiérrez et al [24], with permission from the Massachusetts Medical Society. Copyright c [2008] Massachusetts Medical Society. All rights reserved.