Methodological Limitations of the Study
Due to its methodological limitations, I cannot derive any indications for a possible effectiveness of leech therapy from the study.
The conditions for the trial arms were not even close to being comparable:
- Only patients in the leech therapy group received treatment that included intensive, individual direct physician contact with “careful physical examination” and consultation, according to the eMethods. These participants were able to describe their symptoms in detail and received feedback from the physician as well as confirmation that hardening and swelling were “zones classified as requiring treatment” and so-called “points of maximal pressure sensitivity”. The print version only mentions “local application of leeches”, which is associated not only withthe individual contact to a physician but also with an elaborate process of time the patient spent lying down, placing dressings, changing dressings, and follow-up care;
- in contrast, participants in the control arm (91% of whom had received prior physiotherapy that was unsuccessful) were in groups for which physician consultation was not reported;
The unexplained deviations from the trial protocol registered under EudraCT 2011–004393–28 in the determination of the primary outcome parameters (first visit at 28 days instead of at seven days, as submitted; see www.clinicaltrialsregister.eu) and the statement about “selection bias” from recruiting “in a tertiary study center” remain baffling.
Therefore, I do not perceive the methodology to be balanced, especially as the recruitment of trial participants (which is also not mentioned in the publication) was linked to the promise of a guaranteed leech therapy (of monetary value), as “in every case, each participant will receive a free leech treatment worth the equivalent of 100 Euros” (2).
At best, it can be deduced that surveys of patients who are interested in leech therapy show better results for patients who were directly assigned to their desired method and who have had individual contact with an informed physician, than for those in physiotherapy groups who are still waiting for leech therapy.
Dr. med. Mechthild Waldeyer-Sauerland
Conflict of interest statement
The author declares that no conflict of interest exists.
|1.||Hohmann CD, Stange R, Steckhan N, Robens S, Ostermann T, Paetow A, Michalsen A: The effectiveness of leech therapy in chronic low back pain—a randomized controlled trial. Dtsch Arztebl Int 2018; 115: 785–92 VOLLTEXT|
|2.||Immanuel Krankenhaus Berlin: Studien mit Patienten, die unter chronischen Rückenschmarzen leiden. www.naturheilkunde.immanuel.de/forschung/abgeschlossene-studien/blutegeltherapie-bei-rueckenschmerzen/ (last accessed on 6 March 2019).|