Why report counts rise and fall

A count of reports is shaped by who reports and when, as much as by what happens. FDA states that "many factors can influence whether or not an event will be reported, such as the time a product has been marketed and publicity about an event." The main ones:

How many people use the product

A drug taken by ten million people collects more reports than one taken by ten thousand, whatever happens to either group. FDA: "Common products may have a higher number of adverse events due to the higher total number of people using the product." The data contain no denominator, so no page on this site gives a rate.

Time on the market

New products are watched closely: manufacturers run active surveillance, clinicians report the unfamiliar, and FDA may require extra reporting. Counts for a new product typically rise for a few years and then settle, without any change in the product.

Publicity and litigation

A safety communication, a news story or litigation brings a wave of reports, often of events that happened years earlier. Reports filed by lawyers are recorded as such in FAERS and appear in the "who reported" bands. Some of the largest counts in the database are of this kind.

Manufacturer batches

Manufacturers submit reports in batches, sometimes thousands in one month after a data migration, a follow-up campaign or a change in what they must report. A one-month spike on a month page is usually this.

Reporting rules

What must be reported has changed over the years, and FDA has worked to increase reporting. FDA attributes much of the long-run rise in the total number of reports to improved reporting rather than to more events. Device reporting also changed when FDA ended most summary reporting programmes in 2019, after which some device types show a step up.

Release timing

FAERS is released quarterly and MAUDE monthly, and reports reach FDA months after events. The newest months on every trend chart are incomplete and will grow; a decline at the right-hand edge is expected and means nothing by itself.

Duplicates and incomplete reports

FDA notes that "there are many instances of duplicative reports and some reports do not contain all the necessary information." One event can produce a manufacturer report and a voluntary report, and follow-ups can be counted as new reports in some releases.

None of this makes the counts useless. It means a count is a record of reporting, to be read with the context each page provides and with FDA's statement that a causal relationship cannot be established from a report.