A new study cites a greater emphasis on safety, as well as improved training and communication, as possible reasons for a drop in the rate of reported adverse events and for decreased harm for patients in Veterans Health Administration medical centers. The number of monthly adverse events dropped to 2.4 from the 3.21 reported in a previous study.

The same report found that close calls, events in which significant harm could have been caused but was averted, increased from 1.97 reports per month to 3.24.

Approximately half the adverse events took place in the operating room, but their severity, on average, decreased, according to researchers. The rate of "highest harm" adverse events also fell by 14% each year.

"Overall, the most common root cause for incorrect surgery was ‘critical clinical processes not standardized’," according to the authors, who noted that these were situations in which a clinical process was left to the judgment of the clinician to accomplish.

The second most common root cause was "human factors problems," defined as "problems with the human-machine interface, look-alike packaging of different implant components, and other problems with the environment or time pressures, distraction, or fatigue."