(Research Hub Theater) Body Mass Index Impacts Postacute Rehabilitation Outcomes After Lower Limb Amputation

Background and/or Objectives: The impact of body mass index (BMI) on physical function and clinical outcome measures in patients who received inpatient rehabilitation services for lower extremity amputation are not clear.

Design: Retrospective review of UF-national data from the Select Rehabilitation Hospital System.

Setting: Tertiary care facility.

Participants: Patients with lower extremity amputation (n=951). Patients were stratified into BMI categories adjusted for limb loss mass ( < 25 kg/m², n=209; 25-29.9 kg/m², n=325; 30-34.9 kg/m², n=214; 35-40 kg/m², n=112; and >40 kg/m², n=91).

Interventions: not applicable

Main Outcome Measures: Inpatient Rehabilitation Facility Patient Assessment Instrument functional scores (GG section 6-point independence ratings for self-care activities, body transfers, mobility); length of stay (LOS), discharge location. Deep Learning Neural Networks (DLNNs), were developed to assess relationships between adjusted BMI and outcomes.

Results: The BMI>40 group demonstrated 7-13% lower Toileting hygiene scores, 8-9% lower Sit-to-Lying and Lying-to-Sitting bed mobility scores, 16-21% worse Sit-to-stand scores and 12-20% lower Toilet Transfer scores than the other groups (all p<.001). Walking 50 ft-with-two-turns was most difficult for the BMI>40 group (p=.011) Wheelchair mobility scores for propelling 150 ft were worst for the BMI>40 (4.9 points versus 5.1–5.5 points for other groups; p=.021). LOS was longest with BMI>40 and shortest with BMI < 25 (15.0 d versus 13.3 days; p=.032). Logistic regression analysis indicated that BMI>40 was associated with lower odds risk (OR) of discharge-to-home (OR=0.504 [0.281-0.904]; p<.022). DLNNs found that adjusted BMI and BMI category were ranked 11 and 12 out of 91 model variables in predicting discharge-to-home.

Conclusions: Integrative approaches to managing patients with severe obesity and optimizing functional outcomes should be considered, including nutrition and medications. Adaptations to therapy content could include early emphasis on bed and ambulatory mobility maneuvers and body transfers with strengthening exercises.