Bioavailable turmeric extract for knee osteoarthritis: a randomized, non-inferiority trial versus paracetamol

BACKGROUND: To compare the efficacy and safety of bioavailable turmeric extract versus paracetamol in patients with knee osteoarthritis (OA). METHODS: In this randomized, non-inferiority, controlled clinical study, patients of knee OA were randomized to receive bioavailable turmeric extract (BCM-95®) 500 mg capsule two times daily or paracetamol 650 mg tablet three times daily for 6 weeks. The primary outcome measure was Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC) pain subscale. The secondary outcome measures were WOMAC total, WOMAC stiffness, and WOMAC physical function scores. Responder analysis of individual patients at different levels (≥ 20%, ≥ 50%, and ≥ 70%) for WOMAC score was calculated. TNF alpha and CRP levels were evaluated and adverse events (AE) were also recorded. RESULTS: Seventy-one and seventy-three knee OA patients, respectively in bioavailable turmeric extract and paracetamol groups, completed the study. Non-inferiority (equivalence) test showed that WOMAC scores were equivalent in both the groups (p value < 0.05) in all the domains within the equivalence limit defined by effect size (Cohen’s d) of 0.5 whereas CRP and TNF-α were better reduced with turmeric extract than paracetamol. After 6 weeks of treatment, WOMAC total score, pain, stiffness, and function scores got a significant improvement of 23.59, 32.09, 28.5, and 20.25% respectively with turmeric extract. In the turmeric extract group, 18% of patients got more than 50% improvement and 3% of patients got more than 70% improvement in WOMAC pain and function/stiffness score and none of the patients in the paracetamol group met the criteria. CRP and TNF-α got significantly reduced (37.21 and 74.81% respectively) in the turmeric extract group. Adverse events reported were mild and comparatively less in the turmeric extract group (5.48%) than in the paracetamol group (12.68%). CONCLUSION: The results of the study suggest that bioavailable turmeric extract is as effective as paracetamol in reducing pain and other symptoms of knee osteoarthritis and found to be safe and more effective in reducing CRP and TNF-α. TRIAL REGISTRATION: Clinical Trials Registry – India CTRI/2017/02/007962. Registered on 27 February 2017 SUPPLEMENTARY INFORMATION: The online version contains supplementary material available at 10.1186/s13063-021-05053-7.