We are pleased about the lively discussion on, and interest in, the topic. Dr. Waldeyer-Sauerland expressed concern about disparity of medical examinations and consultations. However, the patients of both groups received a careful physical examination / consultation of analogous duration as part of the study enrollment. The aforementioned investigation immediately before the leech application was an additional, local examination of about one to two minutes, as a prerequisite for adequate leech placement. There were no further medical consultations. It is true that the lying down time and care of dressings occurred only for the leech therapy. We also assume a relevant unspecific active component and have pointed this out (1). Both groups had prior experience predominantly with physiotherapy, which is inevitable with a symptom duration of >10 years; however, physiotherapy was not continuously prescribed for our patients. As physiotherapy is a primary guideline recommendation, recruiting a representative study population without such prior treatment is hardly possible. Expectations, as an important aspect of nonspecific treatment effects, were only slightly lower in the physiotherapy group (3.6 / 5 points) than in the leech group (4.0 / 5 points). Attention was paid to ensure a good quality for both therapies; accordingly, physiotherapy was carried out by specialized personnel.
With regard to the primary outcome criterion, a survey was scheduled for day 7 in the initial EudraCT entry. This date was subsequently corrected (prior to the inclusion of the first patient) to day 28, with the goal of having greater clinical relevance. The final test protocols provided to the ethics committee and the trial registry contained this information. The advertisement of the trial and clarification of the cost neutrality are necessary for recruitment. We pointed out the free therapy as an incentive; accordingly, this was also true for the physiotherapy.
Dr. Barz rightly notes the low therapy response in the physiotherapy group. As the expectations regarding physiotherapy were quite high, we consider the long duration of the symptoms in particular to be a limiting factor. Given the high prevalence of back pain, frequently with a resulting incapacity for work, and the fact that the use of analgesics is one of the leading causes of death in developed countries (see also „opioid crisis“ ), we believe that scientific evaluation of empirically promising procedures is important. The therapeutic act is no longer a hangman‘s meal for the leeches. After use, they are sent back to the breeder, where they continue to live in a protected area.
We thank Dr. May for the information on more extensive work on the mechanisms of action and on other indications. These topics could not be addressed due to space limitations. The efficacy of leech therapy for gonarthrosis, rhizarthrosis, and epicondylitis has meanwhile been proven in studies (3–5).
We would like to significantly correct the comments of Dr. Hübner et al. The symptom load, depicted by pain, ability to function, and quality of life, was not significantly different between the groups; rather, we observed more of a tendency for a higher symptom load in the leech group. Analgesic use at the baseline was not significantly different. A (non-significant) higher mean in the control group was, as mentioned in the manuscript, due to two participants with high analgesic use. “Negative experiences” with complementary and alternative medicine were not raised. The frequencies of prior therapies used during the long-term symptom duration were described, but not their therapeutic success. The use of acupuncture was higher in the control group. If the ANCOVA model is adjusted for the primary outcome criterion with respect to previous acupuncture experience, there is no change in the results (p = 0.002 / day 28). The variable “acupuncture” does not influence the result. Throughout the article, the primary outcome criterion is precisely defined and named. In addition, statistical assumptions / evaluations underlying the eMethods section are described precisely. All secondary outcome criteria were pre-defined and can be included in the evaluation of results upon reaching the primary outcome. Furthermore, Hübner and colleagues formulate fundamentally personal opinions about the quality of research in complementary medicine. How these comments are connected to the present study remains unclear. Our study met common quality characteristics of randomized controlled clinical trials. We consider it expedient, even when discussing divergent positions about a topic, to argue based on facts.
On behalf of the authors
Prof. Dr. med. Andreas Michalsen
Klinik für Innere Medizin, Abteilung für Naturheilkunde
Immanuel Krankenhaus Berlin, Germany
Conflict of interest statement
Prof. Michalsen has received study support (third-party funding) from the Biebertaler Blutegelzucht (Leech Breeding Farm). Biebertaler Blutegelzucht GmbH supported the study with material (provision of leeches) and paid official trial fees, costs of participant health insurance, and pro rata coverage of personnel costs for two months (trial doctor). Prof. Michalsen is the 2nd Chairman of the German Society for the Promotion of Therapies with Hirudinea and Their Protection e.V., and Chairman of the Board of the Karl and Veronica Carstens Foundation; both of these are honorary posts.
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