- Design
- Randomised, double-blind, placebo-controlled trial, 3 months, no concurrent NSAIDs
- Population
- 120 people with symptomatic knee osteoarthritis, Kellgren-Lawrence grades 2 and 3
- Primary outcome
- Between-group change in knee pain on a visual analogue scale
- Effect
- No significant difference in pain, KOOS or effusion size; hsCRP and beta-NGF improved (p < 0.05)
CLOAK randomised 120 people with symptomatic knee osteoarthritis (Kellgren-Lawrence grade 2 or 3) to three months of daily colchicine or placebo, with no concurrent NSAID use. The primary outcome was change in knee pain on a visual analogue scale.
There were no significant differences in pain, KOOS scores or ultrasound effusion size. Subgroups with worse pain, more advanced radiographic disease, or higher baseline hsCRP or urate also showed no clinical benefit. Several inflammatory biomarkers improved with colchicine, including hsCRP and beta-NGF (p < 0.05).
The biomarker changes are a reason for further research, not a reason to prescribe. The authors suggest longer-term benefit is possible but did not show it. Three months is short for a degenerative disease.
- No significant gain in pain, KOOS or effusion size at three months.
- No benefit in subgroups with more severe disease or higher inflammatory markers.
- Inflammatory biomarkers improved, but patients did not feel better.
- Three months of follow-up cannot exclude later benefit.
- This does not support starting colchicine for knee osteoarthritis.
Why it matters
It tests the idea that damping inflammation helps osteoarthritis symptoms, and in this trial it did not.
Don't overread it
A three-month trial cannot rule out longer-term effects or benefit in a differently selected population.
The statistics, in plain English
A biomarker can move without any change in how a patient feels, which is why trials use symptoms as the primary outcome. Some biomarker p-values here were nominal, with trends reported at p up to 0.16, so they are weak evidence.
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