Crowdfunding is the practice of funding a project or enterprise by collecting small amounts of money from numerous people, typically via online platforms. In the past two decades the market of crowdfunding has been growing quickly; crowdfunding has become a new way to finance, for example, start-up companies, projects in the visual arts and music, technological innovation, scientific research, and community projects.
In the last decade, crowdfunding for medical expenses has gained popularity as well, especially in the United States. Bassani et al.  report that 76 medical crowdfunding platforms operating worldwide had raised over $132 million as of October 2017; and that the number of health-related crowdfunding campaigns reached 13,633. In the United States, medical crowdfunding is considered to be a symptom of an inadequate healthcare system; in 2007, 62% of individual bankruptcy filings were related to medical costs due to injury and severe illness . Crowdfunding not only provides relief for a large number of sick people but also helps them to avoid medical bankruptcy [3, 4]. Nevertheless, crowdfunding is a typical tool for obtaining one-off financing; and one-off funding is inadequate to finance chronic diseases and other life-long health problems.
In Europe, medical crowdfunding might be regarded as marginal when compared to the USA. In Europe, as a result of universal health coverage, residents can benefit from adequate, effective and accessible health services and are financially protected. Although the management of health systems varies greatly across Europe, they all provide universal or nearly universal health coverage for their residents . Universal coverage does not imply covering all medical costs for each individual. Typically, not every resident and not all medical procedures are covered. In the healthcare sector, demand for higher quality care is increasing constantly while the healthcare budget is limited. Nowadays, new medications and innovative medical interventions are appearing on the market quicker than ever. Unmet needs for health care emerge as these new medications and innovative medical procedures are typically not financed by national health insurance funds, due either to insufficient information about their efficacy or the required time-consuming legislative changes [6,7,8,9,10,11]. Long waiting times (and thus the incentive to use private health care providers instead of public ones) and patient co-payment  might also motivate individuals to turn to medical crowdfunding.
This study aims at mapping unmet health care needs manifested in medical crowdfunding campaigns in a healthcare system with universal health coverage. In particular, we explore the most common condition, disease or disorder which prompted individuals to turn to crowdfunding in Germany, where universal coverage is provided through statutory and private health insurance. In addition, we reveal the type and size of health-related expenses that individuals aim to finance via crowdfunding. This study is exploratory in nature; it allows a glimpse into the unmet health care needs of residents in a healthcare system with universal health coverage.