World OF DRUG SAFETY MODULE

AERS has just as many limitations:

• Underreporting; FDA does not get most reports of adverse events that occur in the United States. Estimates suggest that FDA receives reports of about 1 to 10 percent of the adverse events that occur.
• Duplicate reporting. FDA can get the same report about the same event from the same person if they send it to the company and FDA, if manufacturers submit follow-up reports as new reports, or if more than one report is sent to the company or FDA by the patient, family member or healthcare providers. There's a manual process to remove duplicate entries but it is time-consuming.
• Variable reporting quality. Some reports are very good; some are not. If reports don't have important clinical information, then it is difficult to determine if the drug was related to the adverse event.
• Reporting biases. Some people report some things more than others.
• Spontaneous report numbers cannot be used to determine incidence of adverse events. Without the total number of cases that occur in the United States, OSE cannot use the data to determine incidence rates of adverse events -- how commonly the event occurs in the population.
• Difficult to attribute events with high background rate and long latency.