Medical crowdfunding might be a viable option for those scientifically proven treatments which are not financed by the German statutory health insurance system for some reason. When funding is requested for a non-resident, a safety gap exists in a system other than the German statutory healthcare system. When funding is requested for an insured individual, then there is a safety gap: the desired medical intervention is not covered at all or it is not covered by the insurance scheme without additional contributions. Frequently requested scientifically proven treatments include, among others, rehabilitation after injury or cancer, surgery, dental or orthodontal treatments, animal-assisted therapies (excluding dolphin therapy), and therapy with medication. Scientifically proven treatments requested only a couple of times include, for example, microimmuno-therapy for cancer patients (n = 2) [91], stem cell transplant for a patient with autoimmune disease [92, 93], antibody-drug conjugate (Adcetris with the active substance of brentuximab vendotin) medication again for a cancer patient [94, 95], and MiraDry therapy for treating excessive underarm sweating [96, 97]. Medical equipment to facilitate mobility might be also listed in this category; although their efficacy is proven they are not financed for some reason.

Policy makers responsible for setting the coverage of the statutory health insurance scheme might consider addressing some of the above-listed safety gaps among insured individuals. In a systematic analysis, the prevalence of medical conditions might be compared with their popularity in medical crowdfunding campaigns. Such a comparison might reveal striking mismatches in the rankings which should act as a warning signal for potential safety gaps. Policy makers should analyse those cases in detail where the condition or desired treatment is mentioned in crowdfunding platforms more often than would be justified on the basis of prevalence rates. One prominent example of such a mismatch is related to lipoedema. As argued above, this mismatch has recently been recognized by the decision-making body of the joint self-government of health insurance funds in Germany, and liposuction is now covered by statutory health insurance for more patients [82]. Given the limited healthcare budget, several safety gaps are acknowledged by the statutory health insurance fund and purposely left with the individual to cover. Prominent examples of such cases include therapies with a low expected success rate (e.g., in-vitro fertilization for women with severe endometriosis) or much higher costs (e.g., orthodontic treatment beyond age 18). Both situations regularly prompted individuals to turn to crowdfunding; as long as the state budget does not allow coverage of such expenses crowdfunding might be a viable option for health financing in these cases.

Medical crowdfunding should be considered as a viable option for experimental therapies; without sufficient evidence, statutory health insurance does not cover such therapies. Donations for experimental therapies were requested in four crowdfunding campaigns. Two patients suffering from cancer aimed to finance innovative cancer treatments: chemotherapy combined with a therapy using exosomes (pumping them in the spinal metastasis) [8], and chemotherapy where methadone, an analgesic against cancer pain, is used as a chemosensitizer [9, 98]. Two patients, one suffering from a rare form of Leukaemia [10], the other suffering from a rare genetic disorder (Limb-girdle muscular dystrophy) were collecting donations for taking part in a research programme [11]. The first patient wanted to visit the Children’s Hospital in Seattle and take part in a study for a Car-T-Cell therapy, while the second aimed at participating in a research programmes on cell and gene therapy development for muscular dystrophy at the Experimental and Clinical Research Centre in Berlin.

Medical crowdfunding might also be considered as a viable option for poorly supported therapies. Treatments funded from donations might increase the evidence base and thus provide sufficient scientific evidence for their efficacy, which in turn might enable the statutory health insurance scheme to add the therapy to the list and cover the cost in the future. Prominent examples of such therapies include Adeli-therapy, Doman-therapy and NeuroScan Balance therapy. Adeli-therapy was requested in four crowdfunding campaigns; the published evidence on this therapy is scant and involves a small number of participants [99,100,101]. Doman-therapy was requested in one campaign [102]. This is a therapy offered for children with special needs in Philadelphia [103]. An early study concluded that data so far available are insufficient to justify the system of treatment [104]; no similar study has yet been published afterwards. Similarly, although NeuroScan Balance is offered in several clinics in Germany [105] and was requested by one individual [106], there is no published evidence on Google Scholar.

Alternative and complementary therapies can also be considered good candidates for medical crowdfunding. Such therapies include, among others, acupuncture, homeopathy, naturopathy, Chinese and oriental medicine, body movement therapy, music and dance therapy [107]. Alternative and complementary therapies might give comfort and increase the well-being of patients and their families. In the sample, donations were relatively frequently requested for traditional alternative therapies (n = 11), while less frequently for dance therapy, typically against Alzheimer’s and other dementias (n = 3). Although such therapies are justified from the point of view that it allows patients to feel better and cope better with their medical condition, the budget of the statutory health insurance fund is limited, and thus does not allow it to cover all costs, including the costs of several alternative and complementary therapies. With an unlimited budget, such therapies should be financed. Crowdfunding is a means to attract additional funding to the budget available for healthcare and thus might work as a complementary tool for health care financing.

Medical crowdfunding might also be considered as a viable option for those medical interventions which increase the well-being of individuals but cannot be considered as traditional, alternative, or complementary therapies. Such interventions include, for example, plastic surgery improving the appearance of a body part, gender change, and dolphin therapy. Regarding the latter, empirical evidence shows that dolphin-assisted therapies most probably only improve the mood of a child and its family while on vacation [108]. Therapies increasing the well-being of individuals were frequently listed as motives in crowdfunding campaigns: cosmetic surgery was mentioned in nine, gender change in four, while dolphin therapy in ten campaigns. Financing such therapies is evidently beyond the scope of universal coverage. Should such therapies be financed by donations from the crowd? We may let the crowd decide on this one.

Scientifically unsupported and dangerous treatments should be neither supported by the statutory health insurance fund nor allowed to be launched on crowdfunding websites. Crowdfunding activity for five such treatments is investigated by Vox et al. [109]: homeopathy or naturopathy for cancer, hyperbaric oxygen therapy for brain injury, stem-cell therapy for brain injury and spinal cord injury, and long-term antibiotic therapy for chronic Lyme disease. Some of these treatments are ineffective (homeopathy for cancer and hyperbaric oxygen therapy for brain injury), while others may result in serious adverse effects (stem-cell therapy for central nervous system injury and long-term antibiotic therapy for chronic Lyme disease) [109,110,111]. Individuals launched four medical crowdfunding campaigns for such treatments on Leetchi, in particular, for naturopathy to cure cancer. As medical crowdfunding platforms provide a forum for spreading inaccurate information about treatment [110], it would be important to develop patient education initiatives and health policies targeted at potential users of scientifically unsupported and dangerous treatments [111]. Otherwise, false hopes will be raised, there will be longer delays in appropriate care, and the survival rate will decrease.