A serious adverse drug event, as defined by the FDA, means an adverse event that results in death, a birth defect, disability, hospitalization or is life-threatening or requires intervention to prevent harm. The events are reported voluntarily to the FDA either directly by or through drug manufacturers, who are required to forward any reports.
From 1998 to 2005, the number of reported serious adverse drug events increased 2.6-fold from 34,966 in 1998 to 89,842 in 2005. The number of fatal adverse drug events increased 2.7-fold during the same time period, from 5,519 in 1998 to 15,107 in 2005.
The number of adverse events increased four times faster than the total number of outpatient prescriptions, which rose from 2.7 billion to 3.8 billion during that time frame.
Although a total of 1,489 drugs were associated with adverse events, a subset of 51 drugs accounted for a large proportion of the problem: Each had 500 or more reports in any given year. This group of drugs accounted for 43.6 percent of the total adverse event reports.
Drugs related to safety withdrawals were a small part of the picture and, within the subset of 500 drugs, declined from 26 percent of all reported events in 1999 to less than 1 percent in 2005.
Pain medications and drugs that affect the immune system were disproportionately represented among those that caused death.
Moore and his colleagues pointed to three main reasons for the increase.
"First, we do have a more aggressive use of drugs in a growing and older population, but that explains only about one-quarter of the problem," Moore explained. "We've also got a whole group of products that have entered the marketplace since 1998 -- biotech problems. They play a significant role in the toll of adverse events. The third thing we saw, and I think it's the discouraging part, is we saw increases in drugs whose risks we've real
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