Bio-optimized Curcuma longa extract is efficient on knee osteoarthritis pain: a double-blind multicenter randomized placebo controlled three-arm study

Henrotin Y, Malaise M, Wittoek R, et al. · Arthritis Research & Therapy

Both co-primary endpoints failed their prespecified analysis. The repeated-measures model found pain relief and improvement in patient global assessment of disease activity in every arm over time, with no significant difference between treatments; everything positive the paper reports after that is post hoc. Pooling the two curcumin doses, the change in global assessment beat placebo at the first follow-up (p=0.016) and at day 90 (p=0.027), and the change in serum Coll2-1 beat placebo at day 90 in the per-protocol population (p=0.031) — all three above the 0.025 threshold the trial set for its co-primary endpoints. On VAS knee pain, a secondary endpoint, each dose beat placebo at day 90 (-29.5 mm and -36.5 mm against -8 mm, p=0.018 each) and the two doses did not differ from each other (p=0.9002). KOOS improved in all three arms and did not separate. Adverse events attributed to the product ran 37% on the high dose, 21% on the low and 13% on placebo (p=0.012).

Population

Adults with knee osteoarthritis, Belgium (three-arm)

Intervention

Bio-optimized Curcuma longa extract (Flexofytol), four or six capsules a day of 46.67 mg turmeric rhizome extract each — 187 mg or 280 mg daily — for 90 days

Comparator

Placebo

Limitations

The operational phase was funded by Tilman SA, which markets Flexofytol; one author is its employee, and another consults for it and chairs the company that manufactures the Coll2-1 immunoassay used as a co-primary endpoint. Three months. Every positive efficacy result is post hoc, and two of them depend on pooling the two dose arms.