Abstract
Introduction
Postoperative dislocation remains a vexing problem for patients and surgeons following total hip arthroplasty (THA). It is the commonest reason for revision THA in the US. Dual mobility (DM) THA implants markedly decrease the risk of THA instability. However, DM implants are more expensive than those used for conventional THA. The purpose of this study was to perform a cost-effectiveness analysis of DM implants compared to conventional bearing couples for unilateral primary THA using a computer model-based evaluation.
Methods
A state-transition Markov computer simulation model was developed to compare the cost-utility of dual mobility versus conventional THA for hip osteoarthritis from a societal perspective (Figure 1). The model was populated with health outcomes and probabilities from registry and published data. Health outcomes were expressed as quality-adjusted life years (QALYs). Direct costs were derived from the literature and from administrative claims data, and indirect costs reflected estimated lost wages. All costs were expressed in 2013 US dollars. Health and cost outcomes were discounted by 3% annually. The base case modeled a 65-year-old patient undergoing THA for unilateral hip osteoarthritis. A lifetime time horizon was analyzed. The primary outcome was the incremental cost-effectiveness ratio (ICER). The willingness-to-pay threshold was set at $100,000/QALY. Threshold, one-way, two-way, and probabilistic sensitivity analyses were performed to assess model uncertainty.
Results
DM THA exhibited absolute dominance over conventional THA with lower accrued costs (US$45,960 versus $47,103) and higher accrued utility (12.08 QALY versus 11.84 QALY). The ICER was -$4,771/QALY, suggesting that DM THA is cost-saving compared to conventional THA. The cost threshold at which dual mobility implants were cost-ineffective was $25,000 (Figure 2), and the threshold at which DM implants ceased being cost-saving was $12,845. Sensitivity analyses demonstrated that the probability of intraprosthetic dislocation, primary THA utility, and age at index THA most influenced model results. In the probabilistic sensitivity analysis, 90% of model iterations resulted in cost savings for DM THA (Figure 3).
Discussion
Dual mobility components showed clear cost-utility advantages over conventional THA components, and DM implants are cost-saving for primary unilateral THA from a societal perspecitve. Model results suggest that DM THA need not be limited to only high-risk patients, although patient age and risk of dislocation are important determinants of its cost-utility.
