Objective Various studies show that the concept of overdiagnosis is difficult to understand. Our aim was to provide an overview of the current knowledge on how information about overdiagnosis is perceived by users of health information, to summarize the findings and to identify research gaps.

Methods A systematic literature review. PubMed, the Cochrane Database of Systematic Reviews, Web of Science, PsycINFO were systematically searched from 1997 to October 2017. Various databases were searched manually. Two reviewers independently screened the titles and abstracts. Quantitative and qualitative studies were included. Data were assessed on the basis of the type of information, type of disease and diagnostic method, outcome, study design and setting and research needs suggested by the authors.

Results 17 Studies were included (10 quantitative, 6 qualitative and one mixed-methods study). Most studies presented overdiagnosis information in relation to mammography and breast cancer. Only one study assessed reception by health professionals. Most of the studies presented written information; only few studies used graphics. Several outcomes were assessed, e.g. prior knowledge, comprehension, intention to undergo screening, attitudes towards screening and informed decision. In summary, prior knowledge of overdiagnosis was low. Various formats could increase knowledge of overdiagnosis. Despite this effect, many people still found it hard to distinguish between overdiagnosis, overtreatment and false-positive findings. Attitudes towards screening remained mainly positive after exposure to overdiagnosis information. Most of the studies showed a negative effect on intention, although it is unclear if this leads to lower participation. One study found that a decision aid including overdiagnosis information increased the number of women making an informed decision.

Conclusion Written and graphical information can help women and men understand overdiagnosis and may help people make an informed decision. Research and public awareness about overdiagnosis seems to increase. But it is still a challenge to adequately communicate the idea of overdiagnosis. Besides written and graphical information, new ways of communicating overdiagnosis need to be investigated. Also, more studies about indications other than cancer screening are desirable.