Nutritional status, body composition and diet in older adults with chronic kidney disease

Abstract

Kidney disease is a public health problem worldwide. The prevalence of chronic kidney disease (CKD) in Sweden is 6% whereas in people above 75 years of age the prevalence is 28%. Diabetes and hypertension are common causes of kidney disease, followed by glomerulonephritis, renovascular diseases, systemic and inflammatory conditions. When renal function decline, many metabolic disturbances occur and several uremic symptoms appear. This may lead to deterioration in nutritional status. Older adults with CKD are an especially vulnerable group, with high comorbidity and symptom burden.

The overall aim of this thesis was to study nutritional status and body composition in older adults with advanced chronic kidney disease who progress towards uremia and start of renal replacement therapy. We identified and described modifiable factors associated with nutritional status decline. Further, we explored if low protein diet was associated with change in nutritional status and body composition over time, and mortality. We used data from a prospective observational cohort study in six European countries (Sweden, Italy, Germany, Poland, The Netherlands, United Kingdom) the EQUAL cohort, including 1739 patients. Patients were followed by their nephrologist ́s, according to standard renal care in each country, and included when the incident glomerular filtration rate (GFR) decreased <20 ml/min/1.73m².

Study I was a cross-sectional analysis of the EQUAL cohort at baseline. The prevalence of protein-energy wasting (PEW) was 26%. PEW was most commonly indicated by the loss of muscle mass and was more common in women, and increased with age (36% > 80 years). We report the 7-point SGA method as a valid method to assess nutritonal status over time in older adults with CKD.

Study II was a prospective study, with one year follow-up data from the EQUAL cohort. Inclusion criteria were patients with 7-p SGA assessment at baseline and at least once during 12 month of follow-up. Nutritional status deteriorated in more than one-third of the study participants during the first year of follow-up. Low patient-reported physical function, gastrointestinal symptoms and smoking were associated with decline in nutritional status.

Study III was an observational study with cross sectional analysis at baseline and prospective analysis after one year. Data collection was performed in two EQUAL centers in Stockholm. Inclusion criteria were patients with information regarding prescribed diet and body composition measurements at baseline and follow-up at 12 months. There was no association between body composition components at baseline or over time with a prescribed low protein diet.

Study IV was prospective with four year follow-up data from the EQUAL cohort. Inclusion criteria were patients with information regarding prescribed diet and SGA measurements. We found similar risk of nutritional status decline and mortality in low-protein diet treated patients as compared with patients on standard diet. However, the risk of mortality increased after two years in those treated with low-protein diet. Continuous follow-up by a renal dietitian should be recommended, regardless of which dietary treatment is prescribed.