Adverse-event figures could be far higher: study

The number of adverse events in hospitals could be far higher—as much as 10 times higher—than was previously estimated, according to a study in the journal Health Affairs.

Using data from nearly 800 inpatients chosen randomly from three large, tertiary-care hospitals in October 2004, researchers looked for adverse events using three methods: hospitals' voluntary reporting systems, the Agency for Healthcare Research and Quality's Patient Safety Indicators, and the Institute for Healthcare Improvement's Global Trigger Tool.

In total, the researchers detected 393 adverse events, occurring in roughly one-third of admissions. Using the IHI's tool, a method that relies on detailed review of patient records, the researchers detected 354 events, or about 90% of the total number of events. AHRQ's Patient Safety Indicators detected only 35 adverse events, or 9% of the total. And that number dropped further when the researchers used hospitals' voluntary reporting systems, which detected only four adverse events, or 1% of the total.

The study's authors warned that hospitals using voluntary reporting systems alone to assess patient safety “may be seriously misjudging actual performance.” They also cautioned against reliance on AHRQ's Patient Safety Indicators, which missed most of the events identified by the IHI's tool, they said.

“As policymakers struggle to measure improvements in patient safety, the results of our study should help inform ongoing efforts to evaluate methods for the detection of adverse events in hospital patients,” the authors wrote.