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Incidence and Types of Adverse Events and Negligent Care in Utah and Colorado

Thomas, Eric J. MD, MPH*; Studdert, David M. LLB, ScD*†; Burstin, Helen R. MD, MPH*; Orav, E. John PhD*; Zeena, Timothy BS*†; Williams, Elliott J. JD; Howard, K. Mason MD§; Weiler, Paul C. LLM; Brennan, Troyen A. MD, JD, MPH*†

Original Articles

Background. The ongoing debate on the incidence and types of iatrogenic injuries in American hospitals has been informed primarily by the Harvard Medical Practice Study, which analyzed hospitalizations in New York in 1984. The generalizability of these findings is unknown and has been questioned by other studies.

Objective. We used methods similar to the Harvard Medical Practice Study to estimate the incidence and types of adverse events and negligent adverse events in Utah and Colorado in 1992.

Design and Subjects. We selected a representative sample of hospitals from Utah and Colorado and then randomly sampled 15,000 nonpsychiatric 1992 discharges. Each record was screened by a trained nurse-reviewer for 1 of 18 criteria associated with adverse events. If ≥1 criteria were present, the record was reviewed by a trained physician to determine whether an adverse event or negligent adverse event occurred and to classify the type of adverse event.

Measures. The measures were adverse events and negligent adverse events.

Results. Adverse events occurred in 2.9±0.2% (mean±SD) of hospitalizations in each state. In Utah, 32.6±4% of adverse events were due to negligence; in Colorado, 27.4±2.4%. Death occurred in 6.6±1.2% of adverse events and 8.8±2.5% of negligent adverse events. Operative adverse events comprised 44.9% of all adverse events; 16.9% were negligent, and 16.6% resulted in permanent disability. Adverse drug events were the leading cause of nonoperative adverse events (19.3% of all adverse events; 35.1% were negligent, and 9.7% caused permanent disability). Most adverse events were attributed to surgeons (46.1%, 22.3% negligent) and internists (23.2%, 44.9% negligent).

Conclusions. The incidence and types of adverse events in Utah and Colorado in 1992 were similar to those in New York State in 1984. Iatrogenic injury continues to be a significant public health problem. Improving systems of surgical care and drug delivery could substantially reduce the burden of iatrogenic injury.

*From the Division of General Medicine, Department of Medicine, Brigham and Women's Hospital, Boston, Massachusetts.

From the Department of Health Policy and Management, Harvard School of Public Health, Boston, Massachusetts.

From the Law Offices of Williams and Hunt, Salt Lake City, Utah.

§From the Colorado Physicians Insurance Company, Denver, Colorado.

From the Harvard Law School, Cambridge, Massachusetts.

Funding was provided by the Robert Wood Johnson Foundation, Princeton, New Jersey.

Address correspondence to: Eric J. Thomas, MD, MPH, University of Texas, Houston Medical School, 6431 Fannin MSB 1.122, Houston TX 77030. E-mail:

Received January 11, 1999; initial review completed March 22, 1999; accepted October 11, 1999.

© 2000 Lippincott Williams & Wilkins, Inc.