Abstract
Introduction
Many worldwide regulatory authorities recommend regular surveillance of metal-on-metal hip arthroplasty patients given high failure rates. However concerns have been raised about whether such regular surveillance, which includes asymptomatic patients, is evidence-based and cost-effective. We determined: (1) the cost of implementing the 2015 MHRA surveillance in “at-risk” Birmingham Hip Resurfacing (BHR) patients, and (2) how many asymptomatic hips with adverse reactions to metal debris (ARMD) would have been missed if patients were not recalled.
Methods
All BHR patients subject to the 2015 MHRA recall (all females, and males with head sizes 46mm or below, regardless of symptoms) at one specialist centre were invited for review (707 hips). All patients were investigated (Oxford Hip Score, radiographs, blood metal ions, and targeted cross-sectional imaging) and managed accordingly. Surveillance costs were calculated using finance department data, as was the number needed to treat (NNT) to avoid missing one case of asymptomatic ARMD.
Results
The overall institutional surveillance cost to investigate all patients once was £105,922 (range £148 to £258 per patient). The most expensive aspects of surveillance were radiographs (£39,598), advanced nurse practitioner assistance (£23,618), cross-sectional imaging (£14,828), and blood metal ions (£14,825). 31 hips had imaging evidence of ARMD (12 revised, with 19 under surveillance). Seven hips were asymptomatic, however all revisions were symptomatic. The NNT to avoid missing one case of asymptomatic ARMD (on imaging and/or requiring revision) was 101 patients, equating to a screening cost of £18,041 to avoid one case of asymptomatic ARMD.
Conclusions
Implementing MHRA surveillance for “at-risk” BHR patients was extremely costly, both financially and logistically. As the risk of asymptomatic ARMD was low, our data suggests the 2015 MHRA surveillance is not cost-effective. We therefore have concerns about the increasingly intensive surveillance recommended in the 2017 MHRA guidance for all metal-on-metal hip arthroplasty patients.
