SAN FRANCISCO, CA—Treatment with hyaluronic acid (HA) for elderly patients with knee osteoarthritis (OA) is associated with significantly longer delay to knee arthroplasty (KA), according to Roy D. Altman, MD, Professor of Medicine at the David Geffen School of Medicine at UCLA, Los Angeles, CA, at the 2015 ACR/ARHP Annual Meeting.

Debate is ongoing regarding the efficacy of intra-articular HA injections as non-operative treatment for knee OA. Although the American Academy of Orthopaedic Surgeons do not recommend use of HA for patients with symptomatic knee OA, other societies are neutral or conditionally recommend this use, with recent analyses identifying beneficial effects compared with saline.

Variation in clinical outcomes are believed to be related to the formulation of HA. Dr. Altman and his team investigated whether: 1) HA injections are associated with a delay in knee OA, and 2) formulation of HA injections has any effect on clinical outcomes.

The retrospective, observational study included patients with knee OA who underwent KA (n=23,008), identified from Part B Medicare data from 2007 to 2012. Time to KA was compared between patients who received HA (n=17,007) vs. without (“no HA”; n=6,001). Patients who received HA were further stratified and compared by HA formulation: bioengineered HA [high molecular weight (HMW) and medium MW (MMW) Bio-HA] and non-bioengineered HA (HMW and low MW [LMW] non-Bio-HA).

Patients treated with HA had a 7.1-month delay to KA (95% CI: 6.6 to 7.5 months; P<0.001) compared to “no HA.” Among all HA formulations, treatment with HMW Bio-HA was associated with the longest time to KA when compared to the “no HA” cohort, 8.6 months (P<0.001). When comparing HA formulations, LMW non-Bio-HA was associated with the shortest time to KA, -2.9 months (P<0.001), while no significant differences were found among the other formulations.

“These results are consistent with prior reports evaluating different patient data banks,” Dr. Altman noted. “It is unclear if the extended time may lead to less KA utilization due to fewer survived patients, or whether the delay could provide additional time for patients to better address or control pre-existing conditions prior to KA, which could aid in reducing postoperative morbidity.

“These findings provide data to fill the evidence gap of the effect of intra-articular treatment on the delay to KA, which has been noted by the Agency for Healthcare Research and Quality to be lacking,” he concluded.