Background: Diagnostic errors probably cause 40,000-80,000 preventable deaths annually in US hospitals alone, and these estimates fail to account for mortality from ambulatory misdiagnosis and non-lethal morbidity due to diagnostic error. Despite their major public health impact, diagnostic errors have received relatively little scientific attention. We sought to further characterize the health outcomes and economic consequences of misdiagnosis in the US through analysis of closed malpractice claims.
Methods: We analyzed misdiagnosis-related claims occurring during a 20-year period (1986-2005) from The National Practitioner Data Bank. We describe error type, outcomes, payments, sources, and geographic distribution. All payment values are reported in 2010 dollars after adjustment for inflation using medical care Consumer Price Index conversion factors (US Bureau of Labor Statistics). Average claims per physician were calculated using American Medical Association physician census data available for selected years (1990, 2000).
Results: Among 11 core malpractice allegation types, diagnostic errors were the leading type (29.1%; n=91,082) and accounted for the highest proportion of total payments (35.6%). The mean number of claims per 1000 US physicians was 8.3 (1990) and 6.3 (2000). The most frequent classes of diagnostic error were failure to diagnose (54%), delay in diagnosis (19%), and wrong diagnosis (10%). The most frequent outcomes were death (41%), significant permanent injury (17%), major permanent injury (13%), and minor permanent injury (10%). The inflation-adjusted, 20-year sum of misdiagnosis-related payments was $34.5 billion (mean-$378,858; median-$208,650; interquartile range $72,250-$472,000). Claims were paid primarily by malpractice insurers (85.9%). The highest total payment sum was in the state of New York ($5.4 billion), and 50% of the total payments over the 20-year period occurred in six states (NY, PA, FL, IL, CA, TX). Total payments for non-lethal injuries accounted for 60%. Per-claim payments for permanent morbidity that was “major” (mean-$568,414; median-$354,000) or “significant” (mean-$417,214; median-$271,950) exceeded those where the outcome was death (mean-$387,899; median-$252,350). The top per-claim payments (mean$825,505; median-$574,200) were for the outcome “quadriplegic, brain damage, lifelong care” (4.3% of cases, 9.2% of total payouts).
Conclusion: Our results indicate that, among malpractice claims, diagnostic errors are the most frequent and most costly of all medical mistakes. We found roughly equal numbers of lethal and non-lethal errors in our analysis, suggesting that the public health impact of diagnostic errors may be far greater than previously imagined. Stakeholders including patients, insurers, hospital systems, and federal agencies have a vested interest in making diagnostic error reduction a patient safety priority.