Evaluating the Completeness and Accuracy of MedWatch Data

The Food and Drug Administration's MedWatch system--a voluntary surveillance program--received 600,000 adverse event reports on marketed drugs and devices in 2011. The Food and Drug Administration credits the MedWatch system with improving awareness, and expediting early detection, of drug and device risks and in illuminating the adoption of medical treatments. Reporting bias has been acknowledged as a limitation of the MedWatch system. No systematic assessment of the accuracy and completeness of adverse event reporting has been conducted, yet inaccurate adverse event reporting may lead drug safety professionals to draw incorrect conclusions, manufacturers may be wrongly forced to suspend and withdraw medications and interventions, health professionals may mistakenly alter their clinical practices, and patients may be denied safe and effective treatments. In 2011, the Tufts Center for the Study of Drug Development gathered and analyzed 10.2 million adverse event reports filed with the MedWatch system. Patient information was generally complete and accurate. Suspect product information, on the other hand, showed high levels of incomplete and inaccurate data. Start and end dates of suspect product use had 37% and 23% completion rates, respectively. Dosage level was completed only 31% of the time, and product lot numbers had only a 9% completion rate. More than 25% of the names of reported suspect products were inaccurate, and 31% of suspect product start dates were inaccurate. Higher levels of completion and accuracy were associated with reports filed closer to the date when the adverse event was observed. Implications of the results and suggested improvements are discussed.