The Harvard Medical Practice Study, published in The New England Journal of Medicine, stands as a foundational reference for understanding the incidence and nature of adverse events and negligence in hospitalized patients. This large-scale study reviewed over 30,000 randomly selected patient records from 51 acute care hospitals in New York State, focusing on hospitalizations in 1984. The researchers sought to provide accurate, population-level estimates of injuries caused by medical management and to clarify how often such injuries were due to substandard care.
The main findings highlight that adverse events occurred in 3.7 percent of all hospitalizations. Notably, more than a quarter (27.6 percent) of these adverse events were attributable to negligence. Most injuries resulted in minor, short-term impairment, but a significant share led to severe consequences: 2.6 percent resulted in permanent total disability, and 13.6 percent led to death. The risk of experiencing an adverse event increased with patient age; individuals over 65 faced more than double the risk compared to those aged 16–44. Furthermore, the likelihood that an adverse event was due to negligence was also higher among elderly patients.
The study found considerable variation in the rate of adverse events across clinical specialties, with vascular surgery showing the highest rates. However, the proportion of events due to negligence did not significantly differ between specialties, suggesting that higher litigation rates in certain fields may reflect the complexity and risk of cases rather than a difference in care quality.
Importantly, the study noted the challenges in reliably judging negligence from medical records, as agreement among physician reviewers was only moderate. Nevertheless, the research demonstrated that many injuries from medical management are indeed preventable, underlining the importance of quality improvement and risk management efforts in hospitals.
In summary, the Harvard Medical Practice Study provided empirical evidence that a substantial number of hospitalized patients suffer injuries related to medical care, and a significant fraction of these are linked to substandard care. The findings underscore the need for ongoing efforts to improve patient safety, particularly for older adults and in high-risk specialties.
Reference:
Brennan, T. A., Leape, L. L., Laird, N. M., Hebert, L., Localio, A. R., Lawthers, A. G., Newhouse, J. P., Weiler, P. C., & Hiatt, H. H. (1991). Incidence of adverse events and negligence in hospitalized patients: Results of the Harvard Medical Practice Study I. The New England Journal of Medicine, 324(6), 370-376. https://doi.org/10.1056/NEJM199102073240604
