The efficacy and safety of medical leech therapy for osteoarthritis of the knee: A meta-analysis of randomized controlled trials
Wang H, Zhang J, Chen L (2018) · International Journal of Surgery · n=264
Study Profile
- Design
- systematic review and meta-analysis of randomized controlled trials of medicinal leech therapy in knee osteoarthritis (Chinese investigators, Shandong)
- Sample size (n)
- 264
- Intervention
- Pooled analysis of 4 RCTs (n=264 total) of medicinal leech therapy in knee OA, updating the Lauche 2014 meta-analysis with additional trials
- Comparator
- Pooled control conditions across included RCTs: topical diclofenac, conventional NSAIDs, TENS, or hyaluronic acid
- Primary endpoint
- Visual analog scale (VAS) pain scores and WOMAC scores at 1 week, 4 weeks, and 7 weeks; adverse-event incidence
- Primary result
- Significant differences favoring leech therapy in VAS and WOMAC scores at 1, 4, and 7 weeks vs control conditions; significantly higher incidence of (predominantly mild) adverse events in leech arms; overall evidence quality rated 'moderate' per GRADE assessment
- Follow-up duration
- up to 7 weeks pooled
- PMID
- 29702260
Key Findings
- Updated meta-analysis of 4 RCTs (n=264) confirms Lauche 2014 finding of significant leech-vs-control benefit for knee OA pain and function
- Significant improvements in both VAS pain and composite WOMAC scores at 1, 4, and 7 weeks vs control
- Adverse events significantly more common in leech arms - predominantly mild local reactions (pruritus, bruising)
- GRADE rating of overall evidence quality: moderate (consistent with ASH editorial-board independent rating)
- Authors caution that the conclusion should be interpreted cautiously given inherent limitations of included studies
Limitations
- Only 4 RCTs included - same general evidence base as Lauche 2014 with limited expansion
- Most included trials open-label with potential for performance and detection bias
- Adverse-event reporting heterogeneous across included trials
- Short follow-up windows (up to 7 weeks) preclude long-term durability assessment
- No subgroup analysis by leech protocol (single vs repeated application) or comparator type
Clinical Implications
Wang 2018 meta-analysis is the most recent quantitative synthesis of the leech-knee-OA RCT literature and confirms the Lauche 2014 conclusion. For US clinicians and guideline writers, the two meta-analyses combined (Lauche 2014 + Wang 2018, both GRADE 'moderate') represent the best available pooled evidence supporting symptomatic leech therapy for knee OA. The slightly higher adverse-event rate is expected and reflects predominantly mild local reactions; serious adverse events remain rare. The conclusions remain conditional on the open-label design of underlying RCTs - the forthcoming ELECT trial sham-controlled result will be the next critical update.
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