The Impact of Excluding Patients with End-Stage Knee Disease in Intra-Articular Hyaluronic Acid Trials: A Systematic Review and Meta-Analysis
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INTRODUCTION: The Kellgren-Lawrence (K-L) grade is the most commonly used measure of radiographic disease severity in knee osteoarthritis (OA). Studies suggest that intra-articular hyaluronic acid (IA-HA) should only be considered in cases of early stage knee OA. The purpose of this review was to determine if trials administering IA-HA in early-moderate knee OA patients demonstrated greater pain relief than studies that also included patients with end-stage disease. METHODS: We conducted a systematic search of the literature to identify randomized controlled trials (RCT) comparing IA-HA with saline injections and that diagnosed disease severity using the K-L grade criteria. The primary outcome was mean change in pain from baseline at 4-13 weeks and 22-27 weeks. Safety was evaluated on the total number of participants experiencing a treatment-related adverse event (AE). RESULTS: Twenty RCTs were included. In the early-moderate OA subgroup, the mean change in pain scores was statistically significant favoring IA-HA from baseline to 4-13 weeks [SMD = - 0.30, 95% CI - 0.44 to - 0.15, p < 0.0001] and within 22-27 weeks [SMD = - 0.27, 95% CI - 0.39 to - 0.16, p < 0.00001]. No significant differences were observed in the late OA subgroup. IA-HA was associated with a significantly greater risk of treatment-related AEs relative to saline in the late OA subgroup [RR = 1.76, 95% CI 1.16-2.67, p = 0.008]. CONCLUSION: IA-HA provides significant pain relief compared to saline for patients with early-moderate knee OA, compared to cohorts including patients with end-stage OA (KL grade 4), with no increase in the risk of treatment-related AEs, up to 6 months. Patients with end-stage disease had lower levels of pain relief and may be diluting study results if included in the treatment cohort. FUNDING: Ferring Pharmaceuticals.