Nutrition Clinical Framework, Mortality, and Length of Stay Among Older Inpatients With Malnutrition.

Importance: The Academy of Nutrition and Dietetics Nutrition Care Process is a standardized, 4-step framework for nutrition assessment, diagnosis, intervention, and monitoring. Although the framework has been widely adopted globally, its association with improved clinical outcomes, including mortality and length of stay (LOS), remains unclear. Objective: To evaluate the association of nutrition clinical framework implementation, delivered as an institutional clinical practice change, with clinical outcomes in older inpatients (aged ≥65 years), with a focus on effect modification by nutrition status. Design, Setting, and Participants: This cohort study using a difference-in-differences design was conducted among older adult inpatients (aged ≥65 years) at a Japanese university hospital between January 1, 2022, and June 30, 2025, with a follow-up period of 1 year after admission. Exposures: Institutional nutrition clinical framework implementation in 9 wards from July 1, 2024, to June 30, 2025, in which dedicated registered dietitians delivered the full 4-step process as part of a hospital-wide clinical practice change. Main Outcomes and Measures: The main outcomes were in-hospital mortality, 6-month mortality, 1-year mortality, overall mortality, and LOS. All outcomes were stratified by Mini Nutritional Assessment-Short Form (MNA-SF) score (≤7, malnourished; 8-11, at risk of malnutrition; ≥12, normal nutrition status). Results: Among 17 057 inpatients included in the study (mean [SD] age, 78.1 [7.5] years, 9070 male [53.2%]), in-hospital mortality in the malnourished stratum was lower during the implementation period (odds ratio [OR], 0.45; 95% CI, 0.22-0.91; P = .03). Nutrition clinical framework implementation was also associated with lower 6-month mortality (OR, 0.59; 95% CI, 0.35-0.98; P = .04) and shorter LOS (exponentiated coefficient, 0.87; 95% CI, 0.77-0.98; P = .03) among malnourished patients; after Benjamini-Hochberg adjustment, these findings were no longer significant. The bayesian posterior probability that the OR was less than 1 was at least 96% in all outcomes, and a dose-response association was observed for LOS (P for trend = .01). Conclusions and Relevance: This study found that ward-based implementation of the nutrition clinical framework was associated with lower in-hospital mortality and shorter LOS among patients with malnutrition at admission, whereas no such associations were observed in the overall cohort. These findings suggest that targeted clinical nutrition delivery may be a useful strategy for prioritizing limited dietitian resources for high-risk inpatients; however, confirmation in multicenter prospective studies is needed.