Spontaneously Low Protein Intake in Elderly CKD Patients: Myth or Reality? Analysis of Baseline Protein Intake in a Large Cohort of Patients with Advanced CKD

Abstract

The recent guidelines on nutritional management of chronic kidney disease (CKD) advise a reduction in protein intake as early as CKD stage 3, regardless of age, to slow kidney function impairment. However, since elderly patients are usually considered as having a spontaneously reduced protein intake, nutritional interventions to reduce protein intake are often considered futile. This study aimed to assess the baseline protein intake of elderly CKD patients referred for nephrology care, and explore the need for dietary evaluations, focusing on the current recommendations for protein restriction in CKD. This is an observational study of CKD patients followed in the unit dedicated to advanced CKD patients in Le Mans, France. Patients with stages 3 to 5 not on dialysis were included. All patients were evaluated by an expert dietician to assess their baseline protein intake, whenever possible on the basis of a 7-days diet journal; when this was not available, dietary recall or analysis of delivered meals was employed. Demographic characteristics, underlying kidney disease, Charlson Comorbidity Index (CCI), Malnutrition-Inflammation Score (MIS), Subjective Global Assessment (SGA) and clinical and laboratory data were recorded. Between 15 November 2017 and 31 December 2020, 436 patients were evaluated in the unit. Their age distribution was as follows: “young”: <60 (n = 62), “young-old”: 60–69 (n = 74), “old”: 70–79 (n = 108), “old-old”: 80–89 (n = 140) and “oldest-old”: ≥90 (n = 54). The prevalence of vascular nephropathies was higher in patients older than 70 years compared to younger ones, as did CCI and MIS (p < 0.001). Moderate nutritional impairment (SGA: B) was higher in elderly patients, reaching 53.7% at ≥90, while less than 3% of patients in the overall cohort were classified as SGA C (p < 0.001). The median protein intake was higher than the recommended one of 0.8 g/kg/day in all age groups; it was 1.2 g/kg/day in younger patients and 1.0 thereafter (p < 0.001). Patient survival depended significantly on age (p < 0.001) but not on baseline protein intake (p = 0.63), and younger patients were more likely to start dialysis during follow-up (p < 0.001). Over half of the patients, including the old-old and oldest-old, were still on follow-up two years after referral and it was found that survival was only significantly associated with age and comorbidity and was not affected by baseline protein intake. Our study shows that most elderly patients, including old-old and extremely old CKD patients, are spontaneously on diets whose protein content is higher than recommended, and indicates there is a need for nutritional care for this population.

Protein Intake and Mortality in Older Adults With Chronic Kidney Disease

“…Results of this multicohort study are in line with those of observational studies [10][11][12] that have found neutral or inverse associations between protein intake and mortality among older persons with CKD stages 3 to 5 not receiving dialysis. First, in 3892 middle aged and older Korean adults, higher total protein intake showed a null association with 11-year all-cause mortality.…”

“…10 Second, among 356 French patients with CKD over 60 years, higher total protein intake was not associated with increased mortality after 3 years. 12 Third, in 259 Japanese adults with CKD and older than 65 years, higher total protein intake was associated with lower risk of all-cause death over 4 years, although participants had been advised to limit protein intake depending on their CKD stage. 11 The latest Cochrane systematic reviews 13,14 of randomized clinical trials found that among adults of all ages without diabetes and with CKD, protein intake of either 0.30 to 0.40 or 0.50 to 0.60 g/kg/d probably does not influence the risk of death when compared with 0.80 g/kg/d or greater, while in adults with diabetic kidney disease, protein intake of 0.60 to 0.80 g/kg/d may make little difference in the risk of mortality when compared with 1.00 g/kg/d or greater.…”

“…[4][5][6] The latest guidelines leave the door open for higher protein intake targets in those with underlying conditions, such as frailty and sarcopenia, but more data are needed to make specific recommendations. 5 Observational studies on mortality in older persons with CKD are often small to moderate in size, are conducted in a single setting, and use point-in-time estimates of protein intake, [10][11][12] while randomized clinical trials commonly include participants with CKD of all ages and lack power to analyze protein intake modification in those who are older. 13,14 The role of protein sources in older adults with CKD is also of interest.…”

The Role of Protein Restriction in the Progression of Chronic Kidney Disease

“…A recent study in France referred that even in elderly CKD patients the protein content is higher than recommended, they are mostly spontaneous in diet and indicates there is a need for nutritional care for this population [54].…”

Plant-based diets for CKD patients: fascinating, trendy, but feasible? A green nephrology perspective

“…Based on some large population studies, it is commonly held that, since protein intake decreases with age and is overall lower in advanced CKD, reducing protein intake in the elderly CKD population is a sterile and useless exercise [ 121 , 122 ]. While this may be true in those cases that are already stabilized with a spontaneous reduction in protein intake, data from our group in Central France suggest that protein intake exceeds 1.2 g/kg/day in about 20% of CKD patients (Stages 3–5 not on dialysis) aged 90 years or above, and is over the 0.6 target in about 60% of CKD patients aged over 80 years [ 123 ].…”