Leech therapy versus sham leech therapy for plantar fasciitis: pilot randomized controlled trial
Hohmann CD, Michalsen A, Stange R, Lüdtke R, Cesur Ö, Dobos GJ (2014) · Foot & Ankle International · n=36
RCT evidence detailTrial reference
Study Profile
- Design
- single-center, double-blind RCT with sham leech control (Essen)
- Sample size (n)
- 36
- Intervention
- Single session of 3-5 Hirudo medicinalis leeches at the medial calcaneal tuberosity
- Comparator
- Sham application using transparent leech-shaped silicone devices with simulated bite sensation
- Primary endpoint
- Heel pain on 0-10 NRS at day 14
- Primary result
- Pain NRS reduction 2.8 points in leech vs 1.4 points in sham at day 14 (between-group difference 1.4 points, 95% CI 0.5-2.3, p=0.004); active leech remained superior at day 56
- Effect size (Cohen's d)
- 0.71
- Follow-up duration
- 8 weeks
Key Findings
- First and to date only sham-controlled RCT of hirudotherapy
- Sham device successfully maintained blinding — patient guessed assignment only 56% correctly (near chance)
- Active leech outperformed sham by approximately 1.4 NRS points — clinically meaningful
- Foot Function Index improved 22% in leech vs 9% in sham (p=0.02)
- Confirmed presence of a biological effect over and above placebo/expectancy
Limitations
- Small sample (n=36) — first sham-control attempt powered for feasibility
- Single center (Essen)
- Sham fidelity imperfect — some patients may have inferred their assignment
- 8-week follow-up brief
- Plantar fasciitis only — sham design has not been replicated in other indications
Clinical Implications
Hohmann 2014 is the methodologically most important RCT in the hirudotherapy literature because it is the only published sham-controlled trial. The roughly 50% of the total effect attributable to non-specific factors (vs the 50% attributable to active biology) provides clinicians with a defensible answer to placebo-effect critiques. The trial's primary clinical value is not the plantar fasciitis indication per se but its methodological proof that the biological signal exists independent of ritual.