About 10 percent of serious and unexpected adverse events are not reported by drug manufacturers to the U.S. Food and Drug Administration under the 15-day timeframe set out in federal regulations, according to an article published by Accounting Assistant Professor Paul Ma.

Health care professionals and consumers can voluntarily report adverse drug events directly to the FDA or the drug manufacturer. Adverse events that are serious (including death, life-threatening, hospitalization, disability and birth defects) and unexpected (any adverse experience not listed in the current labeling) are classified as "expedited" and manufacturers receiving such reports are mandated to forward them to the FDA "as soon as possible but in no case later than 15 calendar days of the initial receipt of the information" under federal regulation.

"Our analysis provided evidence that drug manufacturers delay reporting of serious [adverse events] to the FDA. Strikingly, [adverse events] with patient death were more likely to be delayed,” says Ma.

Ma and coauthors Pinar Karaca-Mandic and Iván Marinovic examined data from the FDA Adverse Event Reporting System for adverse event reports received from January 2004 through June 2014. The final study sample included only initial reports characterized by the FDA as "expedited" and therefore subject to the regulation requiring reports to be submitted within 15 calendar days.

The study, which included more than 1.6 million adverse event reports, estimated that 9.94 percent of the reports (160,383 total; 40,464 with patient death and 119,919 without patient death) were not received by the FDA by the 15-day threshold. The authors' analysis suggests patient death was associated with delayed reporting.

"Drug Manufacturers’ Delayed Disclosure of Serious and Unexpected Adverse Events to the US Food and Drug Administration" Ma, Paul; Marinovic, Iván; Karaca-Mandic, Pinar JAMA Internal Medicine (2015)