Abstract
BACKGROUND: Turmeric has traditionally been used to treat various inflammatory conditions, including knee osteoarthritis (OA). There are multiple turmeric preparations available. However, the comparative effectiveness of these products remains unknown. This study aimed to assess the comparative effectiveness of turmeric products for knee OA outcomes by conducting a systematic review and network meta-analysis of randomized, controlled trials (RCTs). METHODS: PubMed, EMBASE, SCOPUS, and ClinicalTrials.gov databases were searched up to August 2024, identifying RCTs that compared turmeric preparations and/or active comparators versus placebo. The primary outcome measured pain reduction, using the Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC), while secondary outcomes evaluated pain using other tools. Mean differences (MDs) were pooled using a random-effects model, and the concept of minimum clinically important difference (MCID) was considered. RESULTS: Seventeen studies were included. All turmeric preparations significantly reduced WOMAC pain. The mean differences (MD, 95% CI) for WOMAC pain reduction were as follows: - 4.01 (-6.22, - 1.80) for conventional curcuminoid preparations (CT) plus active drug comparators (AC, defined as NSAIDs and acetaminophen), - 3.33 (-5.26, - 1.39) for AC, - 3.17 (-5.50, - 0.83) for CT, and - 2.47 (-3.27, - 1.67) for bioavailability-enhanced curcuminoid preparations (BE). The BE preparation also demonstrated a 30% reduction in WOMAC pain compared to placebo, reaching the MCID threshold. The BE + AC combination led to a 70% reduction in VAS pain compared to AC alone. CONCLUSIONS: All turmeric preparations appear to be effective in reducing knee OA pain when used as monotherapy compared to placebo. However, the certainty of evidence remains low, indicating a need for further research. PROSPERO REGISTRATION NUMBER: CRD42023464749. CLINICAL TRIAL NUMBER: not applicable.