Replication of the Weber Effect Using Postmarketing Adverse Event Reports Voluntarily Submitted to the United States Food and Drug Administration

Study Objective. To validate or refute a widely accepted epidemiologic phenomenon known as the Weber effect by replicating Weber's original observation by using drugs that were marketed in the United States and using reports from a U.S. database. Design. Retrospective analysis of adverse event databases. Setting. University research center. Drugs. The original nonsteroidal antiinflammatory drugs studied by Weber that were approved by the U.S. Food and Drug Administration (FDA) and marketed in the United States: diclofenac sodium, diclofenac potassium, diflunisal, sulindac, flurbiprofen, and piroxicam. Intervention. Reports of adverse events submitted to the FDA's Spontaneous Reporting System and the Adverse Event Reporting System from January 1969–December 2000 for these drugs were analyzed according to the number of adverse events reported for each drug per year from the time the drug was approved until December 2000. Measurements and Main Results. Reporting patterns were considered to demonstrate the Weber effect if the highest peak in reports during the first 5 years after product approval occurred during year 2. All five drugs analyzed in this study demonstrated the Weber effect. Conclusion. The Weber effect was replicable by using drugs marketed in the United States and using reports that were submitted to a U.S. database. Various other factors affected spontaneous reporting of adverse events, as peaks in the number of reports were seen numerous times for each drug after the initial 5-year marketing period.