Nutrition, body composition, inflammation and haemoglobin status among haemodialysis patients on erythropoietin maintenance therapy

Abstract

End stage renal disease (ESRD) is associated with several physiological and metabolic changes which together cause poor health and impair patients’ quality of life. Anaemia is one of the most common metabolic consequences of renal failure and is highly prevalent among ESRD patients. Renal anaemia has a significant negative impact not only on patients’ health outcomes but also poses a heavy economic burden on the health system due to the high cost of treatment. Interactions between nutrition, anaemia status or/and response to anaemia therapies have been suggested. This programme of work aimed to investigate anaemia and nutritional status (including body composition) among haemodialysis (HD) patients and to study how nutrition status and body composition modify patients’ anaemia status and their response to the hormone erythropoietin (EPO). The first two sections of this project were cross-sectional studies conducted to characterise the health status of patients. Firstly, health outcomes were compared between the UK (n = 101) and Tanzanian (n = 96) HD patients after which a more in depth study was conducted in Tanzania only (n = 77). These are presented in chapter 2 and 3 respectively. Both studies showed that Tanzanian HD patients had increased risk of low haemoglobin (Hb) levels, inadequate nutrition and inflammation. The findings showed that body fat and muscle mass were significantly and positively associated with Hb and EPO response. These investigations were then extended to the UK via recruitment and assessment of a cohort of UK adults HD patients on EPO treatment (n = 41). The UK study was conducted longitudinally and included additional markers of anaemia and nutritional status to further assess the relationship previously observed and in an attempt to uncover the mechanisms involved. The findings showed that longitudinally, body fat, significantly and positively influenced Hb concentration independent of EPO type and gender. Equally, there was a positive association between leptin hormone and Hb concentrations, suggesting a potential link and possible mechanism for the observed association between body fat and Hb levels. Finally, building on this work, an exercise intervention of low intensity (walking + intradialytic resistance training) was adopted and conducted as a randomized controlled pilot and feasibility study. The aims were to investigate if such an intervention was feasible and acceptable to patients and staff and capable of inducing favourable changes in patients’ body composition (body fat and muscle), and if so, how any such changes would modify patients response to EPO and their Hb status. The eight week study was unable to achieve significant changes in body composition or iron markers. However, there was a slight improvement in exercise performance and lower body strength assessed through the sit to stand test. To our knowledge, the low intensity exercise protocol used, combining walking + intradialytic resistance training, has not been previously tested in the dialysis setting and offers an acceptable intervention for further research. This programme of work has demonstrated that good nutrition helps improve the EPO response and Hb levels of HD patients. A flexible and low intensity exercise programme involving walking and intradialytic resistance training is feasible and practical in the presence of a physiotherapist. However eight weeks of low intensity exercise is not sufficient to induce changes in body composition or EPO response in HD patients but may help improve their physical functioning and so warrants further investigation as a more cost effective alternative to cycle-based interventions.