Why patient safety is such a tough nut to crack

It’s now more than a decade since the US Institute of Medicine’s landmark 1999 report To Err Is Human put patient safety prominently on the international agenda. Despite countless initiatives, publications, and conferences on the topic, improvement has been disappointingly slow. Ian Leistikow and colleagues define the four challenges that make patient safety such a tough nut to crack, and propose a way out of the impasse