Traction therapy for penile curvature: Poor study situation leaves benefit open and reveals research gaps

The Federal Joint Committee (G-BA) commissioned the Institute for Quality and Efficiency in Health Care (IQWiG) to investigate whether penile induration (induratio penis plastica) can be improved with the help of traction therapy and whether symptoms such as curvature of the penis during erection, pain or impaired sexual functioning can be reduced.

However, there is hardly any meaningful evidence for traction therapy. This is because the only two randomized controlled trials (RCTs) provide little robust data and only for short-term treatment, i.e. observation over three months. Whether traction therapy offers long-term benefits for those affected therefore remains an open question.

However, the study results so far suggest a potential of this method and provide approaches for further research needs. IQWiG has therefore formulated key points for a testing study that can be used to conduct a meaningful trial - to clarify the longer-term advantages and disadvantages of traction therapy compared to no treatment.

Clarify open research questions in a good study

In one of the available studies, traction therapy is shown to reduce penile curvature at the end of the three-month treatment period. However, it remains to be seen whether this effect will last. The study data do not provide clear results on other outcomes such as pain, sexual functioning, symptom burden and side effects. Furthermore, there is a lack of data on psychological impairment and health-related quality of life.

Based on the study data, traction therapy does not show a benefit, but it does show potential as a necessary treatment alternative for PD: Traction therapy could be an alternative for patients who are not (yet) eligible for surgical treatment because of the phase of their disease, or for patients who refuse invasive surgery because of the associated risks. Effective conservative therapy for PD is currently not available in Germany.

The manifestation of induratio penis plastica and the associated suffering vary greatly from individual to individual, which is why the relevant aspects for those affected must be the focus of a study. IQWiG found out what is particularly important for patients in personal interviews: What effects the disease has on life and everyday routine and how those affected deal with it, which goals the treatment should achieve and which experiences they have already had with therapy. An external expert contributed his clinical expertise to the IQWiG assessment of traction therapy.

Testing study with suitable patient population and patient-relevant outcomes

A 2-arm multicentre RCT with a follow-up period of at least one year could demonstrate possible positive as well as negative effects of traction therapy versus no treatment. Patient-relevant outcomes will have to be considered, including sexual functioning, pain, symptom burden, health-related quality of life and side effects of treatment.

The curvature of the penis is the main feature of PD: when erect, it is obvious to those affected and often accompanied by other symptoms, including pain and problems during sexual intercourse. This was also clearly formulated in the discussion with an affected individual. This is exactly where traction therapy comes in and could in principle sustainably stop the progression of or reduce penile curvature in the long term and thus offer fundamental advantages for patients.

In principle, traction therapy can be used both in the stable and in the acute phase of the disease. The participants in the two present studies were predominantly in the stable PD phase. Since the symptoms differ depending on the phase of the disease - acute or stable - the study should include affected individuals in both phases. This is the only way to assess the effect of traction therapy for the entire patient population.

Different devices are used for traction therapy, but the mode of action is comparable. Therefore, all devices that are approved for the European market and are suitable for the treatment of PD are in principle eligible for a study.

Process of report production

On 17 November 2022, the G-BA commissioned IQWiG to conduct a benefit assessment of traction therapy for Peyronie’s disease. IQWiG published the preliminary results in the form of the preliminary report in July 2023 and presented them for discussion. At the end of the commenting procedure, the report was revised and sent as a final report to the commissioning agency in September 2023. The written comments submitted on the preliminary report are published in separate documents at the same time as the final reports. The Institute involved an external expert in the processing of the project. The final report was published in October 2023; the English translation was published in March 2024.

If the G-BA decides to conduct a testing study on the basis of the present IQWiG assessment, the G-BA will define the key points for the planned study in a testing guideline and commission an independent scientific institution to conduct the study.