Reliability and validity of a nutrition screening tool to be used with clients with learning difficulties

Background: People with learning difficulties are nutritionally vulnerable for many reasons. There is a need for a nutrition screening tool (NST) to enable carers to identify those at nutritional risk. However, a validated NST for clients with learning difficulties does not exist. Aim: To assess the reliability and validity of a NST being used in a long-stay hospital in North Staffordshire for people with learning difficulties. The NST investigates three areas of risk: nutritional adequacy (food groups), weight and nutrition-related problems such as dysphagia or gastrointestinal disorders. Method: Thirty-six subjects were randomly selected. The reliability of the NST was assessed by three nurses familiar with the participants. Each subject was independently screened using the NST. Validity was assessed by forming an expert panel of three dietitians. Each participant's nutritional status for each of the three risk areas was assessed independently by the dietitians using their own methods. A comparison of the majority opinion of the dietitians with that of the nurses gave an indication of validity. Results: Reliability was analysed using variance component models and indices of agreement. There was good agreement between nurses in the assessment of risk relating to nutrition adequacy (r=0.658), moderate agreement in the assessment of nutrition-related problems (r=0.576), but only fair agreement in the assessment of weight-related risk (r=0.263). Validity was assessed using Cohen's kappa statistic. There was good agreement between the majority opinions of the nurses and dietitians for the assessment of nutritional adequacy-related risk (r=0.708) and for nutrition-related problems (r=0.691), but only fair agreement for weight (r=0.300). Conclusion: Use of the NST in the area of nutrition adequacy gave good repeatability and validity. Similarly, there was good validity in the area of nutrition-related problems. The NST was not satisfactory in assessing weight-related risk and further work is needed in this risk area. There was also a suggestion from the results of the study that the dietitians differed in their approach to assessing nutritional risk.