Purpose: Advanced hip osteoarthritis (OA) is a common chronic condition causing severe joint pain and loss of joint function. Since 2004,the Alberta Hip Improvement Project (HIP) has been prospectively collecting data on the effectiveness and safety of metal-on-metal hip resurfacing arthroplasty (HRA) and conventional total hip arthroplasty (THA) in younger hip OA patients. The most common hip resurfacing method used in Alberta is Birmingham hip resurfacing, and thus in this study we evaluate the cost-effectiveness of the Birmingham HRA compared to THA.
Methods: A probabilistic Markov decision analytic model was constructed to compare the quality-adjusted-life years (QALYs) and costs of HRA vs THA over a 15-year time horizon from a healthcare perspective. The base case cohort was 50-year old advanced hip OA patients. Data inputs were derived from HIP and the literature. Sensitivity analyses evaluated cohort ages for hip replacement, utilities, failure probabilities, and treatment costs.
Results: In the base case, HRA was less costly and associated with better outcomes, thus HRA dominated THA. THA remained dominated when either only males were assessed or the cohort age decreased to 40y from the base case value of 50y. When either only females were assessed or the cohort age increased to 60y, THA dominated HRA. Threshold analyses determined the percent change of selected variables needed for THA appear on the efficiency frontier rather than being dominated by HRA. Primary HRA surgery costs needed to increase 2.5% from the base case value of $14,746 to $15,115. HRA revision surgery cost or HRA revision probability needed to increase 44% from the base case values of $21,916 and 1.22% (1st y revision probability shown as example—revision probability changes per year) to $31,449 or 6.09%, respectively.
Conclusions: In a cohort of 50-year old patients THA is dominated by HRA. The results of this study, the first to use costs from an observational trial and the first Canadian study, confirm results reported in other studies that HRA is more cost-effective for males and younger patients.