Assessment of medical malpractice cost at a Japanese national university hospital.

Medical safety management has an economic dimension that has received little attention. Medical expenses associated with medical malpractice in Japan should be investigated in relation to patient safety measures and their consequences. We analyzed medical accidents that occurred within the past seven years at a university hospital. We determined that 197 accidents involved negligence by the hospital in the years from 2011 to 2017, for which the institution bore the costs of the resulting treatment; those expenses totaled JPY 30.547 million. Most incidents occurred in the hospital ward (82, 41.6%); those in the operating room were the most expensive (JPY 19.493 million, 63.8%). The greatest number of cases involved drug administration (63, 32.0%). Materials inadvertently left in surgical sites ("remnants") cost the hospital the most per incident (JPY 9.767 million, 32.0%). Of these, medical treatment costs for remnants associated with vascular invasion were the highest. Although the total number of malpractice incidents increased over time, the annual cost to the hospital decreased, especially in cases in which costs exceeded JPY 100,000, and those associated with the operating room. Our results suggested that adverse events must be addressed to foster patient safety, decrease medical expenses, and improve hospital administrative capacity.