Web search data as health data? Geographic differences, temporal trends, and topics of interest from internet search engine analyses in Germany

Background Limited timely, cost-effective, and regional availability of healthcare data is considered one of the limiting factors for timely analyses in the field of health services research and thus for healthcare delivery to the general population. Thus, Internet search engine analyses are coming into focus in this context. Objectives What contribution can data on the volume of Internet searches for various diseases make to the health care of the German population? Where is the potential and where are the limitations? Methods A review of the current literature and a selective overview of Internet search engine analyses of dermatological, allergological, and infectious diseases published in the last 4 years in Germany were performed. Results By analyzing web search data, temporal developments such as seasonality, months with the highest interest, and geographical differences can be mapped at the national, state (Bundeslander), and city level and major points of interest (e.g., skin cancer of the eye or anal itching) regarding a certain health topic can be identified. In addition, some studies were able to show correlations between search volume and external factors (e.g., temperature, care structure) and to registered cases (e.g., skin cancer, Lyme disease). Conclusion Web search data, given the limitations noted, are able to directly provide spatiotemporal mapping regarding the needs of the Internet-using population. They are particularly useful in situations where traditional health data are limited or unavailable.