CoLchicine for Treatment of OsteoArthritis of the Knee (CLOAK): Clinical and biochemical outcomes from a three-month double-blind, placebo-controlled study.
OBJECTIVE: Knee osteoarthritis (KOA) causes pain and progressive disability, but pharmacologic treatments are limited. Colchicine inhibits inflammation that might modulate KOA, but efficacy trials have yielded mixed results. We tested whether colchicine, without concurrent NSAIDs, improved KOA pain, function, synovial effusion size, and OA-associated inflammatory serum biomarkers. METHODS: Participants with symptomatic KOA and radiographic Kellgren-Lawrence grades 2/3 were randomized to receive three months of daily colchicine or placebo in a double-blind manner, with no concurrent NSAID use. The primary outcome was between-group change in visual analog score (VAS) for index knee pain. Secondary outcomes included changes in Knee Osteoarthritis Outcome Scores (KOOS), size (depth in millimeters) of sonographically-identified effusions, acetaminophen use, and changes in OA-related serum biomarkers. RESULTS: From baseline to end of study of 120 enrolled participants, no significant differences were observed in improvement of VAS pain, KOOS scores or effusion size. Subsets of participants with more severe VAS pain, worse radiographic disease, or higher hsCRP or serum urate levels at baseline also showed no significant clinical benefit from colchicine compared to placebo. In contrast to the clinical outcomes, colchicine treatment was associated with significant or trending improvement in multiple OA-related serum biomarkers including hsCRP and β-NGF (p < 0.05) and PGE2, IL-1ra, IL-8, and VEGF (p < 0.16). CONCLUSION: This double-blind placebo-controlled trial of colchicine for KOA failed to demonstrate improvement in pain, function, or synovial effusion size in comparison to placebo at three months. Early improvement in OA-associated inflammatory biomarkers suggests a possible longer-term clinical benefit. Clinical Trials Registration No NCT03913442.