Abstract
Introduction
This study aimed to: (1) compare published follow-up guidelines for metal-on-metal (MoM) hip patients and analyse protocols in relation to current evidence, and (2) assess the financial implications of these guidelines.
Methods
Follow-up guidance for MoM hips from five national authorities (MHRA in the UK; EFORT; United States FDA; Therapeutic Goods Administration of Australia; Health Canada) were contrasted and critically appraised. Using National Joint Registry (NJR) data (67,363 MoM hips implanted) the cost of annual surveillance for all MoM hips recorded in the NJR was calculated for each protocol.
Results
Significant differences existed between recommended guidance, with protocols not reflecting the best available evidence. These include not stratifying patients according to implant type (total hip replacement (THR) or hip resurfacing (HR)) or adverse reaction to metal debris (ARMD) risk factors, using symptoms to decide patient follow-up, and using suboptimal blood metal ion thresholds to identify poorly performing hips. Patients with asymptomatic ARMD lesions, especially HR patients with no ARMD risk factors, would not be identified by most protocols.
Vast cost differences exist between protocols when considering annual surveillance of the NJR population. The MHRA guidance was cheapest for annual follow-up (£8,264,064/10,423,296 Euro/$13,717,440). The most expensive protocols were those recommended by the FDA (£22,321,020/28,134,526 Euro/$37,029,889) and EFORT (£22,708,226/28,590,554 Euro/$37,671,431), both approaching three-times the MHRA costs. The FDA protocol was most costly for surveillance of all symptomatic patients (£18,210,816/22,947,840 Euro/$30,228,480), and EFORTs was most costly for asymptomatic HR patients (£8,283,010 / 10,428,250 Euro / $13,735,495).
Discussion
Current MoM hip follow-up guidance is not evidence-based. Most protocols lack the sensitivity to detect asymptomatic ARMD lesions. It is also clear that these protocols are not financially sustainable in the long-term.
Conclusions
Further work is required to ensure future guidance published by authorities is more unified as well as both clinically and cost effective.
