Understanding Users' Risk Perceptions about Personal Health Records Shared on Social Networking Services.

To understand users' risk perceptions about sharing their PHR on SNS, we first conducted a qualitative user study by interviewing 16 participants. Next, we conducted a large-scale online user study with 497 participants in the U.S. to validate our qualitative results from the first study. Our study results show that a majority of users do not show strong motivation of sharing PHR on SNS due to several concerns such as misuse/abuse and security issues of shared PHR. In particular, participants are highly concerned about sharing diseases and diagnostic test results than other types of PHRs (e.g., details of hospital visits and medical interviews). However, we found about 55.13% of the participants have the experiences of sharing their health-related information on SNS. Also, we learned that users' sharing behavior for disease data can be significantly influenced by the severity/type of the disease as well as preferred recipients. Based on our findings, we propose a recommendation method to automatically determine whether users' posts can be shared with everyone on SNS by analyzing the keywords frequently occurred in health-related posts. Our implementation using Random Forest achieved an F-measure of 87.4%, indicating that PHR can be restrictively shared with high accuracy, when sharing health-related posts on SNS.