Patient-reported outcomes beyond 1 year may be unnecessary for accurate TKA assessment
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Primary total knee arthroplasty patient-reported outcomes through the 1-year follow-up reliably predicted longer-term outcomes, according to results presented the American Association of Hip and Knee Surgeons Annual Meeting.
Abhijit Seetharam, MD, and colleagues conducted a retrospective review of prospectively collected patient-reported outcome measures (PROMs) for 1,093 primary TKA procedures performed by a single surgeon from 2010 to 2018 to determine the value of long-term PROMs in primary TKA. The study received the AAHKS Clinical Research Award.
The study “examined whether the 2-year minimum follow-up after TKA required by most academic journals was necessary for an accurate assessment of patient outcomes after primary TKA,” according to an AAHKS press release.
Need for 2-year PROMs
“We are required to collect all of these PROMs to a minimum of 2 years for most of the journals that we want to publish our research in. Is that really necessary or can we get away with collecting PROMs for a year out for the sake of clinical research?” Seetharam told Healio Orthopedics.
Extended collection of PROMs can pose a burden to physicians, researchers, clinic staff and patients. Therefore, “being able to limit that, I think, is helpful for everyone involved in the process,” he said.
PROMS that the researchers looked at were pain with Knee Society Scores (KSS) for level walking and stair climbing, University of California, Los Angeles (UCLA) activity level and KOOS JR scores at 4 months, 1 year and a minimum of 2 years postoperatively.
Scores improved postoperatively
Results showed KSS, UCLA and KOOS JR scores at all three postoperative timepoints improved from preoperative levels.
“Those are all fairly commonly used outcome measures and they’re the ones we routinely collect, so we were sufficiently powered to study the PROMs that we did at at least an 80% power level,” Seetharam told Healio Orthopedics.
“Along with that, we looked at the minimal clinically important difference or the MCID. We were also sufficiently powered to study that and to draw conclusions for that,” he said.
Regarding reaching the MCID of 6.0 that researchers established, results showed that despite the statistical and clinical significance of the improvement in the PROMs from preoperative to 4 months and 1 year postoperatively, “improvements from 1-year to minimum 2-year follow-up were small and did not reach MCIDs for most PROMs demonstrating significant overlap of 95% confidence intervals,” the researchers wrote in the abstract.
“You do see a plateau between that 1-year and 2-year mark,” Seetharam said. “It certainly was nice to see after just having some anecdotal or kind of experience-driven thought. It’s nice to see the numbers backing that up.”
In addition, patient satisfaction during postoperative follow-up of the study group at 4 months, 1 year and 2 years improved 84%, 87.3% and 90.9%, respectively, according to the abstract.
“Researchers concluded that 1-year PROMs were as clinically reliable and meaningful as 2-year PROMs. While long-term follow-up after TKA remains important for implant survivorship and function, these findings question the necessity of in-person visits to collect PROMs beyond 1 year and suggest that 1-year outcomes are reliably predictive of longer-terms outcomes for peer-reviewed publication,” according to the press release.
Perspective
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Michael J. Dunbar, MD, FRCSC, PhD, FCAHS
This study suggests diminishing returns in trying to obtain TKA PROMs past the 1-year mark and that clinical meaningful improvement as measured by PROMs plateau at 1 year. Care should be taken in interpreting the results, as response rates fall sharply over time with only 56% of patients responding at 2 years in this study. While this illustrates the burden associated with collecting PROMs, it also creates a paradox as, in general, non-responders are less satisfied and report lower PROMs scores than responders. Further, it appears from this study that some PROMs did continue to improve past 1 year. However, most national registries collecting PROMs limit them to 1 year and this study would support this capitation.
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Seetharam A, et al. Are minimum 2-year PROMS necessary for accurate assessment of patient outcomes after primary TKA? Presented at: American Association of Hip and Knee Surgeons Annual Meeting. Nov. 11-14, 2021; Dallas (hybrid meeting).
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