A systematic review and meta-analysis of medical leech therapy for osteoarthritis of the knee
Lauche R, Cramer H, Langhorst J, Dobos G (2014) · The Clinical Journal of Pain · n=237
Study Profile
- Design
- systematic review and meta-analysis of randomized and nonrandomized controlled clinical trials of medical leech therapy for knee OA
- Sample size (n)
- 237
- Intervention
- Pooled analysis of 3 RCTs and 1 controlled clinical trial of medicinal leech therapy in knee OA (Michalsen 2003, Andereya 2008, Stange 2011/2012, plus one CCT)
- Comparator
- Pooled across studies: topical diclofenac, hyaluronic acid, NSAIDs, TENS, or other conventional care
- Primary endpoint
- Standardized mean difference (SMD) for pain, functional impairment, and joint stiffness at multiple time points
- Primary result
- Strong evidence for immediate (SMD=-1.05; p<0.01) and short-term pain reduction (SMD=-1.00; p<0.01); immediate improvement in physical function (SMD=-0.72; p<0.01); both immediate (SMD=-0.88; p=0.04) and long-term improvement in joint stiffness (SMD=-0.62; p<0.01); moderate evidence for short-term function (SMD=-0.46) and long-term pain (SMD=-0.45)
- Follow-up duration
- up to 12 months across pooled trials
- PMID
- 23446069
Key Findings
- First systematic review and meta-analysis of leech therapy for knee OA (pre-dating Wang 2018)
- Pooled n=237 across 3 RCTs and 1 CCT showed strong evidence for pain reduction, functional improvement, and stiffness reduction
- Standardized mean difference (SMD) for immediate pain reduction was -1.05, a large effect by Cohen's conventional thresholds
- Three of four included trials had low risk of bias per the authors' assessment
- No serious adverse events reported in the pooled cohort
Limitations
- Only 4 included trials at the time of analysis (2012 search) - small evidence base
- All included trials open-label - sham-controlled trials (Hohmann 2014, ELECT 2025) not yet available
- Heterogeneous comparators (topical diclofenac, HA, NSAIDs, TENS) reduce interpretability
- Authors note that further high-quality RCTs are needed for conclusive judgment
- Geographic bias - most included trials German
Clinical Implications
Lauche 2014 meta-analysis is the foundational quantitative synthesis of the German leech-OA literature and supports the GRADE 'moderate' rating that the ASH editorial board applies to knee OA. The standardized mean difference of -1.05 for immediate pain (large effect) is one of the strongest pooled effects reported for any non-pharmacologic OA intervention. Clinicians citing the leech-knee-OA evidence should cite this meta-analysis alongside the underlying RCTs (Michalsen 2003, Andereya 2008, Stange 2011/2012). The meta-analysis was updated by Wang 2018 with similar conclusions.
Related Trials
Effectiveness of leech therapy in osteoarthritis of the knee: a randomized, controlled trial
Michalsen A, Klotz S, Lüdtke R, Moebus S, Spahn G, Dobos GJ (2003)
Leech therapy for symptomatic treatment of knee osteoarthritis: results and implications of a pilot study
Andereya S, Stanzel S, Maus U, Mueller-Rath R, Mumme T, Miltner O (2006)
Comparison of modern leech therapy with intra-articular hyaluronic acid injections for symptomatic relief of knee osteoarthritis
Andereya S, Stanzel S, Maus U, Mueller-Rath R, Mumme T, Miltner O, Andereya S (2008)
Effectiveness of home-based cupping massage compared to progressive muscle relaxation in patients with chronic neck pain — a randomized controlled trial (Note: companion knee OA study)
Lauche R, Cramer H, Langhorst J, Dobos G, Michalsen A (2014)