Incidents of serious adverse drug events more than double

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.

They also found that among the most frequently reported drugs associated with fatal events, there were a disproportionate number of pain medications and drugs that modify the immune system.

The researchers say their findings show a marked increase in reported deaths and serious injuries associated with drug therapy over the study period and they say the results highlight the importance of the public health problem and demonstrate the need for improved systems to manage the risks of prescription drugs.

The FDA says it is unclear why there is such an increase in reports, but speculate that an increase in public attention to drug safety, and use of the Internet make it easier for the public to report adverse events to FDA, and could be factors.

The FDA has come in for criticism in recent years from consumer advocates and Congress for its record of approving drugs such as the arthritis drug Vioxx which was withdrawn in 2004 after being linked to strokes and heart attacks.

The agency is also attacked by cancer advocacy groups which accuse the agency of being too slow or too strict in granting approval for the use of experimental new therapies.

The study is published in the Archives of Internal Medicine.