It's day two here in Paris and the World Arthroplasty Congress is in full swing. On the docket today was a handful of discussions relating to the value of national joint registries, such as the Australian Orthopaedic Association National Joint Replacement Registry (AOANJRR), Swedish Arthoplasty registers, and the fledgling American Joint Replacement Registry (AJRR).
One morning topic from the Controversies session, titled Registries Are Severely Biased and Overrated was as interesting as it is straight-forwardly titled. Dr. David Murray's assertion was that registry data is wholly unreliable for comparing outcomes of different types of implants (e.g. comparing primary TKA against unicondylar implants). Often, he argued, registries do not account for surgical technique or indication, and these can be more important than a given implant. Beyond this, Dr. Murray criticized the emphasis on revision rates as a measure of implant success using the Sheehan Knee Replacement System, which dates to the late 1970s, as a lucid example. This relatively primitive knee implant had a near 0% revision rate. Impressive Not when you learn that this was a result of an immense degree of difficulty in revision of the system. From here the point was clear different types of implants have different thresholds for revision, so, comparing various types based on revision rate is inappropriate, and introduces significant bias.
Later on Day Two came a full session dedicated to highlights of various registry outcome reporting, which frequently engaged in just the sort of comparison that Dr. Murray had warned against. Its impact was somewhat compromised.
While registry data is crucial to cut through the veil of advertising in medtech, and plays an important role in the timely identification of poor implant performance, it's clear that understanding registry data and establishing best practices for its use remains an unsolved riddle to some degree.