Comparison of avian and nonavian hyaluronic acid in osteoarthritis of the knee

Robert J Petrella, Anthony Cogliano, Joseph Decaria

Faculties of Medicine and Health Sciences, University of Western Ontario, London, ON, Canada

Background: Hyaluronic acid (HA) in knee osteoarthritis (OA) has been shown to be efficacious and safe, but long-term follow up and head-to-head comparison of products, in particular those of avian versus those of nonavian origin, are lacking.

Objective: The objective was to compare the efficacy and safety of avian and nonavian origin HA in the treatment of knee OA during a long-term follow-up.

Methods: Patients were enrolled on a consecutive basis from all referrals received from 1997 to 2007 at a large primary care referral center in London, Canada. Patients were allocated to commercially available avian and nonavian origin HA based on their own preference for product. Patients were not randomized to therapy nor did the referral center advocate one product versus another. During the period of investigation, three nonavian and two avian products were available in Canada. Injections were given once weekly over three weeks (one series) using a lateral approach. Assessments included body mass index, numbers of medications, number of chronic diseases, duration of knee OA at presentation, visual analog scale (VAS) score (0–10 cm) for rest and weight-bearing pain, patient satisfaction with treatment (5-point categorical scale), numbers of HA series to the point of analysis, previous intra-articular treatment prior to first injection series, adverse events, serious adverse events, and self-payment versus third party payment. Following the first injection series, patients returned to the clinic of their own volition. Inclusion for a second and subsequent injection series was based on a patient request but also requirement of a resting VAS score > 4.5 cm. All patients had radiographic evidence of at least grade 1 OA. Patients who crossed over to alternate avian or nonavian product were not included in the analysis following crossover. Patients could switch within class of HA product. Differences were compared using analyses of variance and were considered significant at P < 0.05.

Results: Four thousand four hundred twelve patients were evaluated for inclusion. Avian or nonavian HA were received by 1,726 versus 1,971 patients, respectively. There were no significant differences in demographic characteristics between groups. There were no differences in reduction of resting pain between groups between the first and 10th consecutive series of HA injections; however, there was a significantly greater improvement in weight-bearing pain (P < 0.01) favoring nonavian HA after the 7th series. There was also a significantly greater number of adverse events (4.8% versus 1.7%; P < 0.01) in the avian- compared to nonaviantreated patients.

Conclusions: Both avian and nonavian HA improve pain in patients with osteoarthritis of the knee. Some difference in weight-bearing pain favoring nonavian HA was seen later in the treatment cycle while a significantly greater number of adverse events was observed in avian HA-treated patients.

Keywords: hyaluronic acid, osteoarthritis of the knee, avian and nonavian