Association of Length of Stay, Recovery Rate, and Therapy Time per Day With Functional Outcomes After Hip Fracture Surgery

IMPORTANCE: Medicare is shifting from payment for postacute care services based on the volume provided to payment based on value as determined by patient characteristics and functional outcomes. Matching therapy time and length of stay (LOS) to patient needs will be critical to optimize functional outcomes and manage costs. OBJECTIVE: To investigate the association among therapy time, LOS, and functional outcomes for patients following hip fracture surgery. DESIGN, SETTING, AND PARTICIPANTS: This retrospective cohort study analyzed data on patients from 4 inpatient rehabilitation facilities and 7 skilled nursing facilities in the eastern and midwestern United States. Participants were patients aged 65 years or older who received inpatient rehabilitation services for hip fracture and had Medicare fee-for-service as their primary payer. Data were collected from 2005 to 2010. Analysis was conducted from November 2018 to June 2019. EXPOSURE: Therapy minutes per LOS day. MAIN OUTCOMES AND MEASURES: Functional Independence Measure mobility and self-care measures at discharge. Patients were categorized into 9 recovery groups based on low, medium, or high therapy minutes per LOS day and low, medium, or high rate of functional gain per day. RESULTS: A total of 150 patients (101 [67.3%] female; 148 [98.6%] white; mean [SD] age, 82.0 [7.3] years) met inclusion criteria. Participants in all gain and therapy minutes per LOS day trajectories were similar in function at rehabilitation admission (mean [SD] mobility, 16.2 [3.2]; F(8,141) = 1.26; P = .27) but differed significantly at discharge (mean [SD] mobility, 23.9 [5.2]; F(8,141) = 14.34; P < .001). High-gain patients achieved mobility independence by discharge; low-gain patients needed assistance on nearly all mobility tasks. Medium-gain patients with a mean LOS of 27 days were independent in mobility at discharge; those with a mean LOS less than 21 days needed supervision with toilet transfers and were dependent with stairs. Length of stay and functional gain rate explained much of the variance in mobility and self-care scores at discharge. Although medium– and high–therapy minutes per LOS day groups were statistically significant in the regression model (β = 6.99; P = .001; and β = 11.46; P = .007, respectively), they explained only 1% of the variance in discharge outcome. Marginal means suggest that medium-gain patients with shorter LOS would have achieved mobility independence if LOS had been extended. CONCLUSIONS AND RELEVANCE: In this study, rate of recovery and LOS in skilled nursing and inpatient rehabilitation facilities were associated with mobility and self-care outcomes at discharge following hip fracture surgery, particularly for medium-gain patients. Therapy time per day explained only 1% of the variance in discharge outcome. Discharging medium-gain patients before 21 days LOS may transfer burden of care to family and caregivers, home health, and outpatient services.