Can a general nutritional screening tool be used to identify haemodialysis patients with increased nutritional risk?

S Jorgensen

York District Hospital

Problem: Malnutrition is a recognised problem in the haemodialysis population and is associated with poor outcomes. In order to reduce the incidence of malnutrition, systems should be in place to identify potential nutritional problems. One such method is the regular use a nutrition screening tool, however a suitably reliable or appropriate renal specific tool does not exist.

Purpose: Initially we considered designing a renal specific tool, however following multi-professional team discussion it was decided to determine whether an existing tool, locally validated for use in the acute setting, could be used to identify haemodialysis patients with an increased nutrition risk.

Design: Chronic haemodialysis patients, receiving thrice weekly haemodialysis, aged over 18 years were recruited into the study over a 6 month period. Nutritional status was assessed using two methods. The first involved a combination of objective and subjective measures, considered as the gold standard for the purpose of the study and the second using the hospital tool. Patients were assigned a level of nutrition risk from each method.

Findings: Seventy patients, with a mean age of 74 years were included in the study. The hospital tool correctly categorised 70% (n=49) of patients, 52.8% (n=37) of which were categorised as having a normal level of nutritional risk and 17.2% (n=12) as having an increased level of nutritional risk. The specificity of the hospital tool was calculated to be 73% and the sensitivity 63%. The 19 of the 70 patients were identified as having an increased risk and therefore the prevalence of malnutrition in the sample was 27%.

Conclusion: Due to the complex nature of renal disease general nutrition screening tools are not sensitive or specific enough to identify haemodialysis patients with increased nutritional risk. In addition, the historical nature of such tools is not appropriate given that such patients are generally well known to the renal team. The prevalence of malnutrition in the sample is consistent with previous findings although toward the lower end of the previously reported scale. The lower prevalence may be due to the local, multi-professional team approach to patient care and also due to the fact that ‘on dialysis’ nutritional intervention is offered to high risk patients.

Relevance: A combined nutritional assessment method using both objective and subjective measures can overcome false negative and false positive results and may be superior to methods previously used to assess nutritional status and level of nutritional risk. Nutrition screening tools should recognise that haemodialysis patients are already at increased nutritional risk and that it is changes in circumstances both medically, economically and psychosocially that can initiate nutritional problems and compromise nutritional status. Given that screening tools that identify patients with the greatest degree of accuracy tend to be the most complex and difficult to administer, and also staffing and workload issues new ways of working should be considered as a way of reducing the incidence of malnutrition.