Comparison of nutritional risk screening tools in patients on admission to hospital

Background and aims: Undernutrition has been frequently reported in patients on admission to hospital. Because this is not always detected promptly, screening for nutritional risk on admission has been widely advocated. Although there is no universally accepted 'gold standard' for defining undernutrition, the definition used by McWhirter, J.P. & Pennington, C.R. [(1994) Br. Med. J.308, 945] has been widely used by clinical nutrition specialists. This study aimed to compare the efficacy of two frequently used nutritional risk screening tools in detecting undernutrition according to this definition. Methods: Both the Nutrition Risk Index [Veterans Affairs Total Parenteral Nutrition Co-operative Study Group (1991) N. Engl. J. Med.325, 525] and the Nutrition Risk Score [Reilly H.M. et al. (1995) Clin. Nutr.14, 269] were used to screen for undernutrition in 359 admissions to two acute teaching hospitals in Dublin. Undernutrition was defined as a Body Mass Index below 20 kg m2 and a triceps skinfold thickness or mid-arm muscle circumference below the 15th percentile. Comparison of stratification of nutritional risk by the two screening tools was carried out. Results: Both screening tools identified over 40% (Nutrition Risk Index, 44%; Nutrition Risk Score, 46%) of all patients assessed as at nutritional risk on admission. However, one-third of the undernourished patients were classified as at no nutrition risk by the Nutrition Risk Index, while almost one-fifth of those undernourished were classified as at low risk by the Nutrition Risk Score. The degree of nutritional risk differed with the screening tool used, the Nutrition Risk Score classifying 29% of all patients as high risk while the Nutrition Risk Index classified only 5% as in the high risk category. Conclusions: Although a large proportion of patients on admission were classified as being at nutritional risk, the degree of risk was significantly different depending on the screening tool used. Both nutritional risk screening tools evaluated in this study failed to recognize many cases of undernutrition. Evaluation of the efficacy of nutritional screening tools should be promoted as seriously as the development of such tools.