One in 20 people receiving medical care may experience preventable harm, according to a meta-analysis of 70 studies involving 337,025 patients. Drugs and interventions such as surgical operations accounted for half of the incidents of preventable patient harm (25 and 24 per cent respectively).

Overall, 6 per cent of patients experienced preventable harm, with the risk highest in intensive care (18 per cent of patients) and surgery (10 per cent) and the lowest in obstetrics (2 per cent). Healthcare infections and diagnostics each accounted for 16 per cent of cases.

In 36 per cent of cases, the patient experienced moderate preventable harm. In 12 per cent of cases, the harm was severe or led to death.

The authors were able to identify only two studies based in primary care.