Consumer Reports Insights

Reports of adverse drug events increase, but the risk can be reduced

Tuesday, February 16, 2010

More than half of all prescription drugs cause adverse effects -- some of them serious or fatal -- that aren't detected until after the Food and Drug Administration has approved them, sometimes many years later.

Such delayed detection contributes to the high number of drug-related injuries in the United States. In 2008 alone, the FDA received more than 100,000 reports of serious injuries related to adverse drug events, an increase of about 25 percent over the previous year, according to the Institute for Safe Medication Practices.

Some of the delay is inevitable: It's simply not practical to detect every risk before doctors start prescribing a drug. Doing so would require clinical trials that would be prohibitively large, long and costly. The 2007 FDA Amendments Act promised many changes in the drug-safety system, but whether they will be sufficient remains to be seen. Here's a closer look at why you face these unexpected dangers, and what you can do to protect yourself.

Holes in trials process

Clinical trials involving drugs that have not yet been approved by the FDA have several limitations, some of them unavoidable. They can't adequately assess safety because they're:

-- Too small. They typically involve only about 500 to 3,000 volunteers, enough to spot only the more common adverse effects. Rarer ones may emerge only after millions of people take the drug.

-- Too short. The trials may last for just a few months, but some adverse effects develop only after patients take a drug for many years.

-- Too unrealistic. Most trials are conducted under scrupulously controlled conditions, with carefully selected patients in order to demonstrate that the drug actually works. Adverse events are not the focus of the studies and therefore may not be detected.

In addition, the FDA may approve some new drugs more quickly than others. The time devoted to preapproval review, particularly for drugs deemed "priority," has dropped substantially since 1992. Congress passed a law designed to speed up the FDA approval process for some drugs to get them to the market faster. But doing so may have come at a significant cost. A 2003 survey of FDA reviewers indicated that they generally felt rushed and, in some cases, pressured by their supervisors to approve medications.

Bigger holes after approval

Because not all hazards can be reliably detected before approval, some are discovered afterward. The system for detecting risks has been the weakest link in the safety system, for several reasons:

-- Incidents aren't reported. Patients, physicians and other health professionals are encouraged to inform the FDA and drug manufacturers about any new adverse drug effects. But it's a voluntary effort, and estimates suggest that only a small fraction of such incidents -- about 1 percent to 10 percent -- are actually reported.

-- Post-approval studies aren't done. Clinical trials published after a drug's approval can reveal previously unknown hazards, but drugmakers are generally not required to conduct such testing and they're not eager to do so voluntarily.

-- Studies aren't published. Drug companies sponsor many studies that are never published in medical journals, often because of unfavorable results.

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