Privacy-Aware Risk-Adaptive Access Control in Health Information Systems using Topic Models

Traditional role-based access control fails to meet the privacy requirements for patient data in medical systems, as it is infeasible for policy makers to foresee what information doctors may need for diagnosis and treatment in various situations. The universal practice in hospitals is to grant doctors unlimited access, which in turn increases the risk of breaching patient privacy. In this paper, we propose a dynamic risk-adaptive access control model for health IT systems by taking into consideration the relationships between data and access behaviors. By training topic models to portray individual and group-level access behaviors, we quantify the risk for each user over a certain period of time. Malicious users are supposed to get higher risk scores than honest users due to improper requests. Thus their further access would be denied under our access control scheme. The topic model and risk scores are periodically updated to advance the self-adaptability of the system. Experimental results have shown that our solution could effectively distinguish malicious doctors even if they deliberately conceal the misconducts.