Patient Migration Makes it Difficult To Track Revisions After Total Joint Replacement Interview with:
Terence J. Gioe, MD
American Joint Replacement Registry, Rosemont, IL
UCSF School of Medicine,
San Francisco VA Health Care System What is the background for this study? What are the main findings? 

Response: Hospital-based or regional registries are typically limited in their catchment area, making loss to follow-up a major concern when patients move out of the area or otherwise receive subsequent medical care outside of the original hospital network. The American Joint Replacement Registry (AJRR), a part of the American Academy of Orthopaedic Surgeons’ (AAOS) registries portfolio, has the goal of tracking total joint arthroplasty (TJA) patients nationally across the US, but currently captures only approximately 28% of annual TJA procedures. Until a nationwide network of reporting hospitals is established that covers at least 90% of all TJA procedures, loss to follow-up due to migration will be a key potential limitation of large-scale studies on implant performance in the US.

Assessment of loss to follow-up can provide an essential understanding of the migration patterns of TJA patients, and help to improve recruitment and enrollment efforts of the AJRR. The magnitude and characteristics of patient migration following TJA have not previously been studied in the US. What is the background for this study? What are the main findings?

Response: The Medicare program is the closest approximation to a nationwide health insurance system in the US; therefore, we used the Medicare program as a pseudo-registry for tracking US arthroplasty patients. Medicare hospital records of beneficiaries enrolled in the traditional Medicare fee-for-service program from January 1, 2004, to December 31, 2015, were queried to identify primary and revision hip or knee arthroplasties.

Five years after the primary arthroplasty, 4.52% of patients (95% CI: 4.50-4.54) moved out of state and another 4.55% (95% CI: 4.53-4.57) moved to a different county within the same state. Western states such as Alaska, Nevada, and Arizona had the highest migration rates, whereas Midwestern states such as Minnesota, Iowa, and Wisconsin had the lowest rates. Florida was the leading destination state, followed by Texas, California, and Arizona. Adjusted for other factors, total knee patients were less likely to migrate out of state than total hip patients (hazard ratio: 0.97, 95% CI: 0.97-0.98 p<0.001). Patients that were older, non-white, or with poorer health status (i.e., with heart disease, obesity or diabetes) were less likely to migrate out of state than younger, white, or healthier patients. 

When hip or knee revisions were performed within one year of the primary arthroplasty, 81.7% (95% CI: 81.4-82.0) were performed in the same hospital and 73.9% (95% CI: 73.6-74.2) were performed by the same surgeon. However, for revisions performed within five years, only 48.8% (95% CI: 48.1-49.5) were performed in the same hospital and 17.2% (95% CI: 16.6-17.7) by the same surgeon. For every additional year after the primary arthroplasty, the likelihood of attending another hospital for revision increased by 9% (relative risk (RR): 1.09, 95% CI: 1.09-1.10, p<0.001). Knee revisions were more likely than hip revisions to be performed at another hospital (RR: 1.11, 95% CI: 1.09-1.12, p<0.001). Patients were less likely to visit another hospital for revision if the primary arthroplasty was performed at a large hospital with 450 or more beds (RR: 0.85, 95% CI: 0.83-0.87, p<0.001), as compared with smaller hospitals with fewer than 150 beds. What should readers take away from your report?

Response: The rate of migration varies significantly among total joint arthroplasty patients in Medicare. Capturing patients who migrate out of state, with associated changes in medical facility, is not feasible without a nationwide network of participating hospitals. Analysis of the performance and longevity of implants based solely on registry data may not reflect the experience of all total joint arthroplasty patients.

The likelihood of attending a different hospital for revision strengthened with increasing time since the primary arthroplasty. These findings reinforce the risk of biased results when implant performance is assessed based only on revisions that can be captured within a limited set of hospitals. Research into implant performance must take precautions to minimize incomplete capture of revision and other post-primary outcomes due to migration or other factors that result in changing facilities at the time of revision. What recommendations do you have for future research as a result of this work?

Response: The AJRR will continue to examine “linked revisions”, i.e. revisions where both the primary and revision procedure is performed within participating AJRR institutions to better understand these migration patterns as our hospital enrollment increases.

Disclosures: I have no disclosures pertinent to this research but I am a Senior Editor for Adult Reconstruction at Clinical Orthopaedics and Related Research.

Citations: AAOS 2018 poster abstract

Is There a Correlation Between Hospital Size and Revision Indication and Where TJA Revision Surgery is Performed? Terence J. Gioe, MD1,2,3, Edmund Lau, MS 4 , Heather Watson, PhD4 , Caryn D. Etkin, PhD, MPH1 ; David G. Lewallen, MD1,5 , Daniel J. Berry MD5 1 American Joint Replacement Registry, Rosemont, IL, USA; 2 UCSF School of Medicine, San Francisco, CA, USA; 3 San Francisco VA Health Care System, San Francisco, CA, USA; 4Exponent, Inc, Menlo Park, CA, USA; 5 Mayo Clinic, Rochester, Minnesota, USA 

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Last Updated on March 19, 2018 by Marie Benz MD FAAD