To evaluate the possible efficacy of medical leeches (Hirudo medicinalis) in the treatment of patients with active osteoarthritis of the knee.
Unblinded, randomised controlled trial with outpatients in a crossover design with single interventions of either leeches or transcutaneous electrical nerve stimulation (TENS) as comparator.
Change in Lequesne's combined index for pain and function and change (L.I.) and overall assessment of complaints by visual analog scale (VAS). Cross-over at day 42, with further observation period of 21 days.
52 out of 72 screened patients were randomised (intent to treat) to initial treatment with either eight leeches (group 1: 27 patients) or TENS (group 2: 25 patients). Due to phase effects, confirmatory evaluation had to be restricted to the first period. Between days 0 and 21, we observed highly significant (p<0.001) improvements for means of Lequesne's index from 12.07 to 9.37 and for VAS from 5.89 to 4.16 cm for leeches, but no significant differences for TENS. Effect size as group difference was -2.50 for L.I. (95% confidence interval -3.88 to -1.11), resp. -1.86 cm for VAS (95% confidence interval -2.85 to -0.87 cm). 12 patients (5 group 1, 7 group 2) did not finish the trial, mostly due to non-compliance (6). No serious adverse effects were observed.
Single leech therapy showed significant, relevant and sustaining effects, comparable to other trials with leeches. The method deserves further research, esp. into mechanisms of possible specific effects and optimization of dosing by number of leeches and possible repeats.