Diet, indicators of kidney disease, and later mortality among older persons in the NHANES I Epidemiologic Follow-Up Study.

Abstract

The purpose of this study was to determine whether diet adversely affected survival among 2572 older persons with indicators of kidney disease in a population-based cohort. Average follow-up time for survivors, of whom 1453 (57%) had died at analysis, was 14.5 years. Kidney disease indicators were a "yes" response to "Has a doctor ever told you that you have kidney disease or renal stones?" and/or trace or greater amounts of protein in urine. Dietary protein intakes were calculated from 24-hour recalls. Cox proportional hazards models were used, stratified by sex, with age, body mass index, blood pressure, education, smoking status, total caloric intake, and diabetes mellitus as covariates. Relative risk of total mortality with an additional 15 g of protein per day was 1.25 (95% confidence interval [CI] = 1.09, 1.42) among White men with kidney disease indicators, vs 1.00 (95% CI = 0.95, 1.06) among those without them; relative risks of renal-related mortality were 1.32 (95% CI = 0.97, 1.79) and 0.95 (95% CI = 0.81, 1.11), respectively. No significant differences were found for White women. Once chronic renal disease is present, diet may be associated with earlier mortality in White males.