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
Michalsen A, Moebus S, Spahn G, Esch T, Langhorst J, Dobos GJ (2002)
Effectiveness of topical gel of medical leech (Hirudo medicinalis) saliva extract on patients with knee osteoarthritis: a randomized clinical trial
Shakouri A, Adljouy N, Balkani S, Mohamadi M, Hamishehkar H, Abdolalizadeh J, Kazem Shakouri S (2017)
Randomised controlled trial with medical leeches for osteoarthritis of the knee
Stange R, Moser C, Hopfenmueller W, Mansmann U, Buehring M, Uehleke B (2012)