Risk of all-cause mortality in subjects with varying degrees of renal impairment with or without dietary protein restriction

Abstract

Background and objectiveLow-protein diet (less than 0.8g/kg/day) has been practiced in the management of chronic kidney disease (estimated glomerular filtration rate [eGFR]<60ml/min/1.73m2 or urine albumin-to-creatinine ratios [UACR] ≥30mg/g) for decades. However, its effect on all-cause mortality is unclear. We investigated the association between a low-protein intake and all-cause mortality in subjects with varying degrees of renal impairment. Materials and methodsWe analyzed participants in the National Health and Nutrition Examination Survey (NHANES) from 2003 to 2010. They were divided into four groups according to their eGFR (≥60 or <60ml/min/1.73m2) and UACR (≥30 or <30mg/g). Daily protein intake of the NHANES participants could be assessed using information from the dietary interview questionnaires. The mortality data was retrieved by linking to the National Death Index till the end of 2011. The hazard ratios for all-cause mortality were evaluated by the weighted Cox proportional hazards regression models. ResultsA total of 8093 participants were analyzed. During a median follow-up of 4.7 years, participants with UACR≥30mg/g (with or without eGFR<60ml/min/1.73m2) had a higher risk of all-cause mortality compared with those having UACR<30mg/g and eGFR≥60ml/min/1.73m2 (reference group). The higher risk of mortality in participants with UACR≥30mg/g was consistently observed in those with or without a low-protein intake. ConclusionsA low-protein intake was not associated with a lower risk of all-cause mortality in subjects with varying degrees of renal impairment.