Effects of leech therapy on knee osteoarthritis: a randomized clinical trial in an Iranian population
Khoshnevisan A, Sahebkar A, Mohammadpour AH, Mosaffa-Jahromi M (2022) · Journal of Traditional and Complementary Medicine · n=80
Study Profile
- Design
- single-center, open-label, randomized controlled trial (Mashhad)
- Sample size (n)
- 80
- Intervention
- Two sessions of 4-6 Hirudo medicinalis leeches, 21 days apart, periarticular knee application
- Comparator
- Naproxen 500mg twice daily for 6 weeks plus standard knee exercises
- Primary endpoint
- WOMAC composite score at week 6
- Primary result
- WOMAC composite reduction 41.2 points in leech vs 23.8 in naproxen at week 6 (between-group difference 17.4 points, p<0.001); effect maintained at week 12
- Effect size (Cohen's d)
- 0.89
- Follow-up duration
- 12 weeks
Key Findings
- First Iranian RCT for hirudotherapy in knee OA — adds non-European, non-North-American data
- Compared against oral NSAID (naproxen) rather than topical — more rigorous comparator
- Effect size consistent with German trials despite different patient population (Iranian, more rural)
- Inflammation markers (CRP, IL-6) reduced significantly in leech arm — first inflammatory-biomarker RCT data
- No serious adverse events; mild local pruritus in 22% of leech patients
Limitations
- Single center, Iran — local Persian medicine context may bias patient expectations
- Open-label
- No assessor blinding for WOMAC
- 6-week comparator phase may underestimate naproxen's sustained effect
- Biomarker findings exploratory — not powered as primary endpoint
Clinical Implications
Khoshnevisan 2022 extends the knee OA evidence base outside the German/European tradition for the first time at the RCT level. Comparing against oral NSAIDs (the global standard) rather than topical diclofenac strengthens the clinical applicability. The exploratory CRP/IL-6 biomarker data provide preliminary mechanistic confirmation of the anti-inflammatory hypothesis. For US clinicians, this trial adds important external generalizability.
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