The cost of outpatient versus inpatient total hip arthroplasty: a randomized trial

BACKGROUND: One route to mitigate the increasing costs of total hip arthroplasty (THA) is outpatient THA, discharging patients on the same day as their surgery. The purpose of this study was to compare the cost of outpatient THA to standard overnight stay in hospital. METHODS: This was a preliminary analysis of the first group of patients to complete follow-up in a larger randomized controlled trial among patients who underwent primary THA through a direct anterior approach between June 2015 and November 2017. The study was conducted at a single centre among patients of 1 fellowship-trained arthroplasty surgeon. We randomly allocated participants to be discharged either as outpatients or on postsurgery day 1 using a modified Zelen consent model. Adverse events were recorded. Participants completed cost questionnaires 2, 6 and 12 weeks after surgery, and the Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC) before and 12 weeks after surgery. We performed cost analyses from health care payer and societal perspectives. RESULTS: A total of 115 participants completed this study, 49 allocated to the outpatient group and 56 to the inpatient group. The adverse event rate was similar for the 2 groups. The WOMAC total score and function subscale score were higher for the outpatient group than the inpatient group at 12 weeks (mean difference 2.1, 95% confidence interval [CI] 0.0 to 4.1, and 6.5, 95% CI 0.4 to 12.5, respectively). From both a health care payer and a societal perspective, inpatient THA was more costly than outpatient THA (mean difference $1006.86, 95% CI -$2158.92 to $145.21, and $1667.40, 95% CI -$3856.64 to $521.84, respectively). CONCLUSION: Our results suggest that outpatient THA may be a cost-saving procedure compared to inpatient THA from both health care payer and societal perspectives. Further study with larger samples is needed to provide more precision around our estimates. TRIAL REGISTRATION: ClinicalTrials.gov, no. NCT03026764.