AB1185 POLYACRYLAMIDE HYDROGEL FOR THE TREATMENT OF KNEE OSTEOARTHRITIS: 3 YEAR FOLLOW UP RESULTS OF A PROSPECTIVE CLINICAL STUDY

Abstract

BackgroundPolyacrylamide hydrogel (iPAAG), manufactured by Contura International, is CE marked for the symptomatic treatment of patients with knee osteoarthritis (OA).iPAAG fulfils an unmet clinical need for an effective, long-acting and safe non-surgical treatment that may postpone knee surgery for those with OA.ObjectivesTo evaluate the efficacy and safety of a single injection of 6 ml intra-articular iPAAG on knee symptoms in participants with moderate to severe knee OA for up to 5 years after treatment.MethodsIn this prospective, multicentre study (3 sites in Denmark) participants received a single intra-articular injection of 6 mL Arthrosamid®. The initial 1-year study was extended to follow the participants for up to 5 years. The study was approved by the Danish Health authorities and the local Health Research Ethics committee. All participants provided informed consent prior to study activities and signed a new consent form to participate in the extension phase.Injections were given by an investigator experienced in administering intra-articular injections. Participants could continue analgesics (except 48 hours prior to visits) and non-pharmacological therapy, but topical (on target knee) and systemic corticosteroids or additional injections were not allowed.Outcomes included the WOMAC pain, stiffness and function subscales (0-100 score where 100 was worst) and Patient Global Assessment of disease impact (PGA). Changes from baseline in these outcomes were analysed using a mixed model for repeated measurement (MMRM) with a restricted maximum likelihood-based approach. The estimated changes based on the least square means were presented including 95% confidence limits and corresponding p-values. Additional sensitivity analyses were for the 3-year data. The MMRM analysis was repeated, but only data from the 35 participants that continued into the extension phase were included. In another analysis an ANCOVA model was used where missing values at 3 years were replaced by the participants baseline value (BOCF).Results49 participants (31 females) with mean age of 70 years (range 44 – 86 years) were treated with iPAAG. 46 participants completed the 1-year assessment and 35 participants (22 females) continued into the extension phase. A site closure and the increased length of the study were the most common reasons for not continuing. 29 participants completed the 3-year follow-up.The originally planned MMRM analysis including all available data from the 49 treated participants showed clinically relevant and statistically significant decreases from baseline to 3 years for each of the 3 WOMAC subscale scores and the PGA (Table 1).Table 1.Analyses of change from baseline to 3 years in transformed (0-100) WOMAC subscalesNumber of participantsLSMean (95% CI)p-valueAt baselineAt 3 yearsWOMAC pain subscalePlanned analysis4929-18.0 (-24.9; -11.1)<0.0001Extension participants3529-17.7 (-24.7; -10.8)<0.0001Baseline carried forward4949-12.1 (-17.0, -7.3)<0.0001WOMAC stiffness subscale4929-16.4 (-22.5; -10.3)<0.0001WOMAC Phys. Function subscale4929-14.9 (-21.4; -8.4)<0.0001Patient Global Assessment4929-15.0 (-27.6; -2.4)0.0223The analysis only using the data from the extension phase participants showed a similar change from baseline in the WOMAC pain subscale compared to the result of the planned analysis (Table 1). The BOCF analysis also showed a clinically relevant and statistically significant decrease in the WOMAC pain subscale from baseline.74 adverse events have been reported in the study including 19 new events reported between the 2-year and 3-year visits. None of the new events were assessed as related to treatment and Covid-19 infection was the most frequently reported AE in this period. 3 of the new events were SAEs (Covid-19 infection, pre-syncope, uterine prolapse).ConclusionSingle injections of 6 ml intra-articular iPAAG are well tolerated and continue to provide clinically relevant and statistically significant effectiveness at 3 years after treatment.REFERENCES:NIL.Acknowledgements:NIL.Disclosure of InterestsNone Declared.