Body Mass Index and nutritional status are predictors of functional improvement from rehabilitation in older patients

Abstract

Background Effective rehabilitation can help older patients regain function and independence during recovery from a period of illness and deconditioning. Body weight and nutritional status may influence rehabilitation outcome for older patients, but this relationship remains unclear. Objective We sought to explore the impact of Body Mass Index (BMI) and Malnutrition Universal Screening Tool (MUST) score in determining functional outcome during general rehabilitation in older patients. Method We conducted a UK-based prospective study of the correlation between BMI and MUST score with rehabilitation outcome. We recruited older patients undergoing general (non-stroke, non-orthogeriatric) rehabilitation from two rehabilitation units (Royal Bournemouth Hospital) over a 2.5 year period. All patients had BMI and MUST scores calculated. MUST score was calculated from a combination of three components: BMI score + weight loss score + acute disease effect score; a higher MUST score of ≥2 delineated a worse nutritional status. Cognitive function was measured using the Mini Mental State Examination (MMSE). Functional improvement during rehabilitation was assessed by calculating the difference between the admission and discharge Barthel Index. Co-morbidity level was assessed using the validated Carlson Co-morbidity Index. Informed consent was obtained from all patients involved. Results 115 patients were recruited: 70 were females and the mean age was 84.7 (S.D. 6.3) years. 80 of the 115 patients (69.5%) showed functional improvement in their Barthel Index. There was no significant difference in gender, admission Barthel Index, Carlson Co-morbidity Index, or MMSE between those with and without functional improvement. Patients with BMI <20 were significantly less likely to show functional improvement (14/35 vs. 14/80, p=0.01), and patients showing functional improvement had a significantly higher BMI (24.1 vs. 20.9, p=0.03). These results remained significant after adjusting for case mix (p=0.02). Patients with MUST score ≥2 were less likely to show functional improvement (14/35 vs. 13/80, p=0.008), and those with MUST score <2 had a higher rate of functional improvement on Cox regression analysis (see Figure). Conclusion Low BMI and poor nutritional status are both independent predictors of lower functional gain from general rehabilitation in older patients. Further research on the effects of improving the BMI and nutritional status as a strategy to improve rehabilitation outcome is warranted.