The Rise of Medicare Advantage is Impacting the Fidelity of Traditional Medicare Claims Data: Implications for Reporting of Long-Term Total Knee Arthroplasty Survivorship.

Abstract

Traditional Medicare (TM) claims data are widely used by researchers and registries to report survivorship following total knee arthroplasty (TKA). The purpose of the present study was to investigate whether the mass exodus of patients from TM to Medicare Advantage (MA) has compromised the fidelity of TM data. We identified 11,717 Medicare-eligible patients (15,282 knees) who had undergone primary TKA from 2000 to 2020 at a single institution. Insurance type was analyzed, and 84% of TKAs were covered by TM. The rates of survivorship free from revision or reoperation were calculated for patients with TM coverage. The same survivorship end points were recalculated after censoring of patients who transitioned to MA after primary TKA, thereby modeling the impact of losing patients from the TM dataset. Differences in survivorship were compared. The mean duration of follow-up was 10 years. From 2000 to 2020, there was a decrease in TM insurance (from 94% to 68%) and a corresponding increase in MA insurance (from 0% to 19%) among patients undergoing TKA. Following TKA, 25% of patients with TM coverage switched to MA. For patients with TM at the time of surgery, the 15-year rates of survivorship free from any reoperation or revision were 90% and 96%, respectively. When patients were censored upon transition from TM to MA, the 15-year rates of survivorship free from any reoperation (92% versus 90%; hazard ratio [HR] = 1.2; p = 0.001) or any revision (97% versus 96%; HR = 1.3; p = 0.002) were significantly higher. One in 4 patients left TM for MA after primary TKA, effectively making them lost to follow-up within TM datasets. The mass exodus of patients out of TM resulted in falsely elevated estimates of survivorship free from reoperation and from revision, with increasing divergence in survivorship over time, when MA data were excluded. As MA continues to grow, efforts to incorporate these data will become increasingly important. Therapeutic Level III . See Instructions for Authors for a complete description of levels of evidence.