SAN DIEGO – Viscosupplementation using hyaluronic acid injections delayed total knee replacement for patients with knee osteoarthritis by up to a median 2.6 years in a retrospective observational study.
The study, involving analysis of a large commercial health insurance claims database (Truven MarketScan), included all 16,529 patients with knee osteoarthritis (OA) who made their first visit to a specialist for the condition in 2008-2011 and who eventually went on to total knee replacement surgery.
Dr. Roy D Altman
Among this group were 4,178 knee OA patients who underwent one or more courses of treatment with any of the Food and Drug Administration–approved injectable hyaluronic acid products. A total of 3,647 of these patients were successfully matched to controls with knee OA who had total knee replacement surgery without any prior hyaluronic acid injections, Dr. Roy D. Altman explained at the annual meeting of the American College of Rheumatology.
The matching process relied upon propensity scores based on age, sex, physician specialty, diagnosis at the first specialist visit, and year. Therein lays a significant study limitation: These variables provide only limited ability to adjust for any differences in baseline knee OA severity that might have existed between patients who did or didn’t receive hyaluronic acid injections. Nor can an observational study establish causality, observed Dr. Altman, professor emeritus of medicine at the University of California, Los Angeles.
That being said, the study demonstrated a strong dose-dependent relationship between viscosupplementation and time from first specialist visit to knee replacement surgery, he noted.
Seventy-nine percent of patients who got hyaluronic acid injections received a single course consisting of either one injection or a series of injections, depending upon the specific product. Those patients experienced a median 233-day increase in the time to surgery, compared with matched controls who didn’t get hyaluronic acid injections.
Moreover, the 16% of viscosupplementation recipients who underwent a second round of treatment further delayed their median time from first specialist visit to total knee replacement by an additional 7 months. And that pattern continued in the relatively small numbers of patients who underwent three or more courses of viscosupplementation: Each round of hyaluronic acid injections brought a roughly 7-month further delay in time to surgery, out to a total of 2.6 years.
The study was sponsored by Johnson & Johnson. Dr. Altman reported having no financial conflicts.