Hyaluronic Acid Injections in Medicare Knee Osteoarthritis Patients Are Associated With Longer Time to Knee Arthroplasty

Background: Few nonoperative treatment options for knee osteoarthritis (OA) are available, but there is ongoing debate about the effectiveness of intra-articular (IA) hyaluronic acid (HA) injections. We investigated whether the formulation of IA HA, or its combined use with IA corticosteroid (CS), may be contributing to some of the reported variation in clinical outcomes. Methods: The 5% Part B Medicare data (2005-2012) were used to identify knee OA patients who underwent knee arthroplasty (KA). The time from diagnosis of OA to KA was compared between patients with (HA) and without (no HA) IA HA use, using quantile regression with propensity score adjustment. These were further stratified by type of IA HA. Patient factors associated with time to KA were also assessed using Cox regression. Results: The "HA" cohort was associated with a longer time to KA of 8.7 months (95% confidence interval: 8.3-9.1 months; P < .001) compared with the "no HA" cohort, with extended time to KA in the bio-engineered Euflexxa IA HA cohort. Patient factors associated with longer time to KA included women, younger patients, minority patients, patients with fewer comorbidities, and IA CS injection use. Patients with both IA HA and IA CS had an additional 6.3 months (95% confidence interval: 5.5-7.0 months; P < .001) to KA over those with only IA HA. Conclusion: In a large cohort of elderly patients undergoing KA, there was a significant longer time from diagnosis of OA to KA in those receiving IA HA. It is unclear if the extended time may lead to less KA utilization. (C) 2016 Elsevier Inc. All rights reserved.