Around one in 20 patients are affected by preventable harm in medical care, of which around 12% causes permanent disability or death, according to a study published by The BMJ.

Preventable patient harm is a serious problem across medical care settings globally, and early detection and prevention is an international policy priority. Several previous reviews have examined overall patient harm across different settings, but none have focused on preventable patient harm.

Most preventable harm relates to drug incidents and invasive procedures and it is more common in surgical and intensive care units than in general hospitals.

It accounts for an estimated £7.3 billion excess charges in the US. Similarly, the financial cost from only six selected types of preventable patient harms in English hospitals is equivalent to over 2000 salaried GPs or over 3500 hospital nurses each year.

Therefore, strategies targeting preventable patient harm could lead to major improvements in medical care and considerable cost savings for healthcare systems across the globe.

Prevalence of preventable patient harm

A team of researchers led by Maria Panagioti from the NIHR Greater Manchester Patient Safety Translational Research Centre set out to measure the prevalence of preventable patient harm across a range of medical settings, including hospitals and in primary care. They also examined the severity and most common types of preventable patient harm.

Their findings are based on data from 70 observational studies involving 337,025 mostly adult patients. Of these, 28,150 experienced harmful incidents and 15,419 experienced preventable harmful incidents.

Around 12% of the preventable harm was severe (causing prolonged, permanent disability or death), while incidents relating to drugs and other treatments accounted for almost half (49%) of preventable harm

Compared with general hospitals, preventable harm was more common in patients treated in surgical and intensive care units, and was lowest in obstetric units.

Despite the unique focus on preventable patient harm and several method strengths, this review has some limitations, say the authors. For example, variations in study design and quality of documentation used for detecting preventable patient harm may have led to differences in prevalence estimates.

Nevertheless, they say their findings "affirm that preventable patient harm is a serious problem across medical care settings" and "priority areas are the mitigation of major sources of preventable patient harm (such as drug incidents) and greater focus on advanced medical specialties."