#303 "I Don't Think I Can Share My Health Information ..." : Understanding Users' Risk Perceptions about Personal Health Records Shared on Social Networking Services

Social networking services (SNS) provide an active online environment to exchange personal health information. However, it would be dangerous to share users' personal health record (PHR) on SNS without considering security and privacy risks. 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 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 of shared PHR and security issues. 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. 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 practical privacy setting method to automatically determine whether a given post 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 98.7\%, indicating that PHR can be restrictively shared with high accuracy, when sharing health-related posts on SNS.