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Registries are an asset for patients and an ally for surgeons
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The Plan-Do-Check-Act cycle is a management optimization technique that can be used to organize a hospital. Perhaps this same cycle involves the basics of the Hippocratic oath, which is adopted by a hospital manager to continuously improve the quality of patient care and I hope is something done by all physicians during consultations with their patients and during surgery.
This interpretation of the Plan-Do-Check-Act (PDCA) cycle would imply the best choice for a total joint implant is always made for the specific patient. Nevertheless, some implants have shown mediocre to worse clinical results, even in recent years, despite the confidence an individual orthopaedic surgeon has in that specific implant for his or her patient.
The metal-on-metal (MoM) hip articulation problem is the most recent, best-known worldwide disaster in orthopaedic medicine. Although the problem was recognized late in the adoption and use cycle, it underscored for the first time, on a global level, how important data from national orthopaedic implant registries are for patient safety. The analysis of a large number of aggregated data within a registry database permits the detection of an early sign of lesser performing joint prostheses. Because of registries and their ability to track outcomes with a large number of implants, even if the revision rates appear to be low with a particularly prosthesis, it is possible now to detect whether these are indeed well above the expected revision rates. In the past, it took many years for such information about revision rates to be detected within private or hospital-based orthopaedic practices.
Case in point, the MoM situation was the first time a problem of such a magnitude was detected from a single national registry — Australian Orthopaedic Association National Joint Replacement Registry. It was then picked up by several other national registries worldwide that showed similar outcomes with MoM hip replacement. This information ultimately resulted in the withdrawal from the market of certain MoM total hip products.
Implant classification guides choices
The Orthopaedic Data Evaluation Panel (ODEP) in the United Kingdom and the Netherlands Implant Classification of the Netherlands Orthopaedic Association use cohort data and/or national registry data to classify hip and knee implants in three or more categories. Such classification helps guide, not dictate, the surgeons’ choice of implants for their patients. Both classifications apply a mean survival of greater than 90% at 10-year follow-up, which is a high rating, to implants. Those implants with fewer years of follow-up receive a lower rating. However, it is possible in the future that those implants with a lower classification might eventually turn in better results at the 10-year mark. If that happens, then these move up within the classification hierarchy.
Ideally, prostheses in the categories or classifications rated highest should be based on data from at least two national registry data sources that have a minimum of 500 patients with no more than 15% of them lost to follow-up. Thus, registers can be used to guide orthopaedic surgeons in their choice of implants for the average patient based on real-life data – national registry data.
Registers should be part of the prosthesis evaluation toolbox (PET), which is one aspect of a dynamic PDCA cycle and of orthopaedic interventions and diagnostics that support the continuous improvement of process and benefit of patients.
There are many aspects of the PET. It starts with close monitoring of new implants within a user group, which is a practice proposed by the Beyond Compliance initiative of the British Orthopaedic Association and involves a minimum safety dataset on new implants that must be evaluated by the surgeons. It requires a radio-stereometric analysis (RSA) study be performed on a small group of implants to ensure bone-implant fixation is adequate. Finally, all the data for the implants in question must be collected, analyzed and then looped back to the orthopedic surgeons to help them make informed clinical decisions.
Are we there yet?
Orthopaedic registries are still emerging within Europe. The Scandinavians have the longest track record with registries. The National Joint Replacement Registry for England, Wales, Northern Ireland and the Isle of Man is the largest in the world. Finally, a U.S. registry is emerging, as well. These increased numbers of registries will foster greater global collaboration concerning common implant problems. Within Europe, we have collaboration within Scandinavian countries through the Nordic Arthroplasty Register Association, through the new Network of Orthopaedic Registries of Europe (NORE) of the European Federation of National Associations of Orthopaedics and Traumatology, and on a global level, through the International Society of Arthroplasty Registers (ISAR).
At the same time, collaboration (ie, data comparison) requires agreement on variable definitions and the granularity of data, and it also poses problems in data comparison due to the sheer differences among health care systems, such as access to health care, waiting lists, etc., even within Europe itself. More importantly, differences among registries in terms of completeness, which can range from more than 95% to 50% complete or less, may invalidate comparisons of results between countries or regions that might have proved helpful.
Furthermore, there are other methodological issues with respect to registry data to consider. These include the validity of collected data, such as how information on infection was collected, and how endpoints are defined, such as by revision surgery or death at 10-year follow-up. These issues are important to work out now because misinterpretation of some of these potentially robust national registry data might discredit registries in general and thus reduce their value for surgeons and patients.
International registry collaboration a necessity
In the near future, guidelines for methodology to analyze these large national registry databases will be developed, which is an initiative of the International Medical Device Regulators Forum. Trials performed using data from within national registries — nested trials — will be performed more often. There will also be greater use of guidelines for classifying attributes of orthopaedic prostheses for the knee, hip and shoulder, for example, using a matrix with attribute lists that correspond to each implant’s material, surface finish, shape, etc. This harmonization will facilitate analysis of groups of implants from different manufacturers so the effect of a particular attribute, such as the effect of a polished, tapered CoCr stem on survival, can be effectively compared.
International collaboration within registry networks, but also the participation and cooperation of the orthopaedic industry, is needed to complete this process.
In regard to new hip and knee prosthetic designs, industry has slowly changed its focus from delivering just a new implant with a theoretically superior design to one of greater care and caution. The latter is underscored by the fact the orthopaedic industry now better acknowledges the benefit of practices like RSA and such initiatives as ODEP, the United Kingdom’s National Institute for Health and Care Excellence, and Beyond Compliance, as premarket tools for better safety and quality. In general, the orthopaedic community has come to appreciate national registries for what these are: pre- and post-marketing evaluation tools that provide data to help ensure patients are safely treated with quality devices that have outstanding long-term track records. Initiatives for registry collaborations between NORE and ISAR, for example, aim to stimulate and facilitate this.
Today, with extensive performance and outcomes data available for orthopaedic prostheses, it is unethical to not thoroughly evaluate the outcome of such a life-changing medical intervention as joint arthroplasty.
- For more information:
- Rob Nelissen, MD, PhD, is chairman of the Network of Orthopaedic Registries of Europe, and chairman and professor in orthopaedics at Leiden University Medical Center. He can be reached at PO Box 9600 (J-11-R), 2300 RC Leiden, Netherlands; email: r.g.h.h.nelissen@lumc.nl.
Disclosure: Nelissen reports no relevant financial disclosures.