Relation between malpractice claims and adverse events due to negligence. Results of the Harvard Medical Practice Study III

N Engl J Med. 1991 Jul 25;325(4):245-51. doi: 10.1056/NEJM199107253250405.


Background and methods: By matching the medical records of a random sample of 31,429 patients hospitalized in New York State in 1984 with statewide data on medical-malpractice claims, we identified patients who had filed claims against physicians and hospitals. These results were then compared with our findings, based on a review of the same medical records, regarding the incidence of injuries to patients caused by medical management (adverse events).

Results: We identified 47 malpractice claims among 30,195 patients' records located on our initial visits to the hospitals, and 4 claims among 580 additional records located during follow-up visits. The overall rate of claims per discharge (weighted) was 0.13 percent (95 percent confidence interval, 0.076 to 0.18 percent). Of the 280 patients who had adverse events caused by medical negligence as defined by the study protocol, 8 filed malpractice claims (weighted rate, 1.53 percent; 95 percent confidence interval, 0 to 3.2 percent). By contrast, our estimate of the statewide ratio of adverse events caused by negligence (27,179) to malpractice claims (3570) is 7.6 to 1. This relative frequency overstates the chances that a negligent adverse event will produce a claim, however, because most of the events for which claims were made in the sample did not meet our definition of adverse events due to negligence.

Conclusions: Medical-malpractice litigation infrequently compensates patients injured by medical negligence and rarely identifies, and holds providers accountable for, substandard care.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Clinical Competence
  • Data Collection
  • Hospitalization
  • Iatrogenic Disease / epidemiology*
  • Insurance Claim Reporting / statistics & numerical data
  • Malpractice / statistics & numerical data*
  • Medical Records
  • New York / epidemiology