Usefulness of the Chinese Nutrition Screening (CNS) tool in predicting 12 month mortality in elderly Hong Kong Chinese living in institutions

Abstract

Objectives: To determine the cut off score of the CNS in predicting 12 months mortality. Design: Data was collected and followed up from a previous study among elderly subjects (n = 515) living in community institutional setting. The risk of malnutrition and 12 months mortality was ranked by the CNS and compared with that by SGA. Reliability was assessed by the sensitivity and specificity of the prediction with SGA as well as BMI alone. Sensitivity and specificity was calculated to determine validity as well as using positive and negative predictive values in predicting mortality at 12 months. Results: All three tools (BMI, SGA, CNS) demonstrated significant difference of higher mortality rate (P<.001) in the malnourished group. CNS at score ≤ 21 showed comparable results to SGA tool and BMI at classifying malnutrition. And using cut off score ≥ 22 also show significant results with SGA in classifying patients with normal nutrition. CNS score at ≥ 22 sensitivity was 60.9% and specificity was 72.9% with a Negative Predictive value of 92.3% and a Positive Predictive value of 25.8%. Conclusion: CNS tool at cut off ≥ 22 is just as good as using BMI or SGA in identifying those who have a normal nutritional status. This is useful in particular, when biochemical or anthropometric data is not available. This further validates the use of ≥22 as the best cut off point with the CNS tool and just as good at predicting of mortality when compared with SGA and BMI assessments.