Adverse drug reactions (ADRs) are a major source of preventable morbidity and mortality, especially among the elderly, who are both more sensitive to and are taking larger numbers of different medications. The insurance industry has recently addressed this problem through the implementation of drug interaction alerts to pharmacists in conjunction with immediate online claims adjudication for almost 60% of prescriptions (expected to reach 90% within 5 years). These alerts are based on stored patient drug profiles of PBMs which are updated whenever prescriptions are filled. While these alerts are very helpful, the pharmacist does not prescribe, resulting in time-consuming and costly delays to contact the physician to remedy potential interactions. Having demonstrated the feasibility of making the drug profile and interaction information easily available to the physician before the prescription is written, we propose a controlled clinical trial to assess potential cost savings. Patient-specific drug profiles will be made available to physicians at each visit of 12,000 patients receiving managed care to a multispecialty clinic, with an identical number at a similar clinic serving as controls. Charts from hospitalizations of both groups will be reviewed using established criteria to measure the proportion caused by ADRs. The study is designed to detect a 10% reduction in ADR hospitalizations, which would produce sufficient cost savings to facilitate widespread adoption of the system. PROPOSED COMMERCIAL APPLICATION: Widespread application of our proposed system has the potential for dramatic cost reductions. Hospitalizations due to adverse drug reactions (ADRs) cost $12.4 billion annually. If only 10% of these hospital admissions are prevented, potential net savings is over $700 million per year, without considering costs of outpatient and unreported ADR illness, lost time from work, and other costs.