Effect of Obesity on Postacute Outcomes of Skilled Nursing Facility Residents with Hip Fracture

Abstract

Objectives: To examine the effect of obesity (body mass index (BMI)≥30.0 kg/m² ) on outcomes of older adults admitted to skilled nursing facilities (SNFs) for hip fracture postacute care (PAC).

Design: Retrospective cohort study.

Setting: U.S. Medicare- and Medicaid-certified SNFs from 2008 to 2015.

Participants: Medicare fee-for-service beneficiaries discharged to a SNF after hospitalization for hip fracture (N=586,683; n=82,768 (14.1%) meeting obesity criteria). Exclusion criteria were aged younger than 65, being underweight (BMI<18.5 kg/m² ), and SNF use in the year prior to index hospitalization.

Measurements: Residents were divided into 4 BMI categories according to cutoffs that the World Health Organization has established: not obese (BMI 18.5-29.9 kg/m² ), mild obesity (BMI 30.0-34.9 kg/m² ), moderate obesity (BMI 35.0-39.9 kg/m² ), and severe obesity (BMI≥40.0 kg/m² ). Robust Poisson regression was used to compare differences in average nursing facility length of stay (LOS) and rates of 30-day hospital readmission, successful discharge to community, and becoming a long-stay resident (LOS>100) according to obesity level. Models were adjusted for individual-level covariates and facility fixed effects.

Results: Residents with mild (adjusted relative risk (aRR)=1.16, 95% CI=1.12-1.19), moderate (aRR=1.27, 95% CI=1.20-1.35), and severe (aRR=1.67, 95% CI=1.54-1.82) obesity were more likely to be readmitted within 30 days than those who were not obese. The average difference in LOS between residents without obesity and those with mild obesity was 2.6 days (95% CI=2.2-2.9 days); moderate obesity, 4.2 days (95% CI=3.7-5.1 days); and severe obesity, 7.0 days (95% CI=5.9-8.2 days). Residents with obesity were less likely to be successfully discharged and more likely to become long-stay nursing home residents.

Conclusion: Obesity was associated with worse outcomes in postacute SNF residents with hip fracture. Efforts to provide targeted care to residents with obesity may be essential to improve outcomes. Obesity may be an overlooked risk adjuster in quality-of-care measures and in payment reforms related to PAC for individuals with hip fracture.

Keywords: hip fracture; nursing facility, successful discharge; obesity; postacute care.