Epidemiology of medical error

TLDR

Media reports highlight medical error but offer little detail, and clinicians often underestimate its risk, while Harvard and Australian population studies provide the only large‑scale data on hospital injury rates. We review the epidemiology of medical error, focusing on prevalence, consequences, common types, clinician groups, and risk factors for injury. The authors analyzed large chart reviews—30,121 admissions in 51 New York hospitals (1984) and 14,179 admissions in 28 Australian hospitals (1995)—to estimate adverse event rates of 3.7 % and 16.6 %, respectively. In the United States, medical error leads to 44,000–98,000 excess deaths and 1 million injuries annually, with 69 % of injuries attributable to errors that are more common among inexperienced clinicians, new procedures, older or complex patients, urgent care, and prolonged hospital stays.

Abstract

Newspaper and television stories of catastrophic injuries occurring at the hands of clinicians spotlight the problem of medical error but provide little insight into its nature or magnitude.1 Clinicians, patients, and policymakers may underestimate the magnitude of risk and the extent of harm. We review the epidemiology of medical error, concentrating primarily on the prevalence and consequences of error, which types are most common, which clinicians make errors, and the risk factors that increase the likelihood of injury from error. #### Summary points The Harvard and Australian studies into medical error remain the only studies that provide population level data on the rates of injuries to patients in hospitals and they identified a substantial amount of medical error #### In the United States medical error results in 44 000–98 000 unnecessary deaths each year and 1 000 000 excess injuries Errors often occur when clinicians are inexperienced and new procedures are introduced Extremes of age, complex care, urgent care, and a prolonged hospital stay are associated with more errors ### Benchmark studies The Harvard study of medical practice is the benchmark for estimating the extent of medical injuries occurring in hospitals. Brennan et al reviewed the medical charts of 30 121 patients admitted to 51 acute care hospitals in New York statein 1984.2 They reported that adverse events—injuries caused by medical management that prolonged admission or produced disability at the time of discharge—occurred in 3.7% of admissions. A subsequent analysis of the same data found that 69% of injuries were caused by errors.3 In a study of the quality of Australian health care, a population based study modelled on the Harvard study, investigators reviewed the medical records of 14 179 admissions to 28 hospitals in New South Wales and South Australia in 1995.4 An adverse event occurred in 16.6% of admissions, resulting in … A subsequent analysis of the same data found that 69% of injuries were caused by errors.3 A subsequent analysis of the same data found that 69% of injuries were caused by errors.3