To establish a reliable, concise, prediction model-based nutritional risk assessment scale applicable for nursing home-dwelling older people, and test its reliability and validity.

A survey using a questionnaire consisting of general demographic information and the Malnutrition Risk Assessment for Elderly Adults (WS/T 552-2017) was conducted with a convenience sample of 1 411 elderly people in 12 nursing homes of 6 cities, from November 2019 to January 2020. Variables screened by item analysis were included in an ordinal, multinominal Logistic regression model, and the statistically significant ones of them were then incorporated into a decision tree model. After that, ROC analysis was used to estimate the AUC of Logistic regression model and decision tree model in predicting nutrition status to select a better model to develop a concise nutritional risk assessment scale, and to determine the diagnostic threshold for nutrition status. Cronbach's α, exploratory factor analysis, estimation of AUC, sensitivity, specificity, Youden index and Kappa coefficient were used to evaluate the reliability and validity of the scale.

For predicting good nutrition, malnutritional risk, and malnutrition, the AUC of Logistic regression model was 0.962, 0.942, 0.989, respectively, and that of the decision tree model was 0.914, 0.868, and 0.968, respectively, indicating that the Logistic regression model was better, and suitable for developing the nutritional risk assessment scale. The final concise Nutritional Risk Assessment Scale for Nursing Home-dwelling Older People is composed of 10 items: BMI, changes in weight in recent 3 months, ability of engaging in daily activities, dental status, nervous and mental diseases, number of illnesses, types of drugs used, time spent on doing outdoor activities independently, eating ability, and the circumference of the shin. The total score of the scale for nursing home-dwelling older people can be 0-14.5 points, with 0-3.0 stands for good nutrition, 3.5-7.5 for nutritional risk, and 8.0-14.5 for malnutrition. The Cronbach's α of the scale was 0.463. Exploratory factor analysis obtained five common factors with eigenvalues greater than 1, explaining 69.9% of the total variance. When predicting the malnutritional risk, the AUC of the scale was 0.902, with 0.799 sensitivity, 0.870 specificity, and 0.670 Youden index. When predicting malnutrition, the AUC of the scale was 0.976, with 0.809 sensitivity, 0.953 specificity, and 0.761 Youden index. The Kappa coefficient for the scale was 0.627. The nutritional status of the 1 411 participants assessed by the scale was: 634 (44.93%) had good nutrition, 639 (45.29%) had malnutritional risk, and 138 (9.78%) had malnutrition.

The concise, Nutritional Risk Assessment Scale for Nursing Home-dwelling Older People developed using a Logistic regression model has proven to have good reliability and validity, which could be used as a tool to identify malnutrition risk or malnutrition in nursing home-dwelling older people.