Incidents of serious adverse drug events including deaths reported to the U.S. Food and Drug Administration (FDA) rose by more than double over a seven year period and painkillers and immune-system boosters were responsible for most.
The FDA receives such reports on a voluntary basis via its Adverse Event Reporting System (AERS) known as "MedWatch" which reach the FDA either directly or through the drug manufacturers, who must forward them on to AERS.
The FDA's definition of a serious adverse drug event is an adverse event that results in death, a birth defect, disability, hospitalization, was life-threatening or required intervention to prevent harm.
A study conducted by researchers at the Institute for Safe Medication Practices in Pennsylvania analyzed serious adverse drug events reported to the FDA through AERS from 1998 through 2005 and found that growing numbers of patients are experiencing serious injuries from drug therapies.
Thomas J. Moore, and his team at the institute analysed a total of 467,809 serious adverse events and found the annual number of reports increased 2.6-fold from 34,966 to 89,842, while the number of fatal adverse drug events increased from 5,519 to 15,107 in the same time frame, a 2.7-fold increase.
The researchers say the overall relative increase was four times faster than the growth in total U.S. outpatient prescriptions, which grew in the same period from 2.7 billion to 3.8 billion.
It was found that a total of 1,489 drugs were associated with adverse events, but a subset of 51 drugs that each had 500 or more reports in any year, accounted for 203,957 or 43.6 percent of the total adverse event reports in the study.
The team say despite that, drugs related to safety withdrawals were a modest share of all reported events and declined in importance over time.
It appears that in the subset of 51 drugs with 500 or more reports in a year, the percentage of reported events associated with drugs related to safety withdrawals declined from 26 percent in 1999 to less than 1 percent in 2005.