Aims: The CurKOA trial aimed to compare the efficacy of Curcuma longa extract versus placebo for treating knee pain and effusion-synovitis in knee osteoarthritis (OA).
Methods: In this double-blind trial, we randomised 70 participants with significant knee pain (>40 mm knee pain on VAS scale), knee OA (ACR clinical criteria) and presence of a moderate amount of ultrasound-defined effusion/synovitis (>4 mm thickness in the suprapatellar region) on ultrasound to receive Curcuma longa extract (80% Turmerosaccharides+20% Curcuminoids extract, 2x500 mg capsules/day) (n=36) or identical placebo (n=34) for 12 weeks. The primary outcome measures were change in knee pain (assessed by VAS) and MRI-defined effusion-synovitis volume over 12 weeks.
Results: Of the 112 participants screened, a total of 70 participants (age 61.8±8.6 years, 56% female) were randomised, and 97% completed the 12-week assessments.
There was a reduction in VAS knee pain in the treatment (-23.75[-29.78,-17.73]) and placebo (-14.64[-20.80,-8.47]) group, with a significant between-group difference of -9.11mm[-17.79,-0.44] (Figure1a) equivalent to a standard effect size of 0.49. There was a no significant between-group difference (1.25 mL[-1.21,3.72]) in the MRI assessed effusion-synovitis volume.
Significant changes favouring the treatment group were seen in WOMAC knee pain (between-group difference: -47.22[-81.22,-13.22]) (Figure1b), WOMAC function (-112.26[-222.79,-1.74]) and OARSI-OMERACT treatment responders (63% in the treatment and 38% in the placebo [Risk Ratio=1.64(1.00,2.70)]. No significant change in T2 relaxation time of the femoral cartilage (-0.38 ms[-1.10,0.34]) was seen. The number of adverse events was similar in the treatment (n=18) and placebo (n=29) groups, and there were no adverse events related to the treatment.
Conclusion: Curcuma longa extract significantly improved knee pain in knee OA patients with effusion over 12 weeks compared to placebo. There was a moderate standard effect size of the treatment. In this short term study, Curcuma longa extract had no effect on knee structural measures assessed using MRI.