Table 4.

Main technical challenges of extracting information from the Health Social Web

Challenges	Description
Relevance [94]	To determine which information is relevant for personalization is complex, and it depends on the objectives of the personalization.
Reliability and validity	The reliability and validity of the information used for personalizing is heterogeneous. Users can fake information about themselves [95] or the Web content they create [96].
Integration	Many Health Social Web applications are not integrated. However, some platforms provide open APIs to integrate third party applications [53]. Integration across different platforms can be achieved using semantic technologies [97].
Privacy-preserving extraction of personal information	Preserving privacy while user modeling and data mining [98,99]