Diagnostic Error Among Medicare Beneficiaries Discharged from the Emergency Department in 2022-2024

The Agency for Healthcare Research and Quality report estimated that 5.7% of ED visits involve a diagnostic error, but overall estimates were determined from studies conducted outside the US. Empirical, broad-based estimates of diagnostic error in US EDs are lacking. This study sought to quantify how often older Medicare beneficiaries discharged from the ED died after discharge or were hospitalized with an Emergency Diagnosis-Sensitive Condition (EDSC) within 9 days.

We identified ED discharges from nonfederal, acute care hospitals in the 50 United States and DC from 2022-2024 among a cohort of 100% of traditional Medicare beneficiaries ages 65 and older who used the ED at least once from 2012-2024. Potential major diagnostic error was defined as death or an admission for an EDSC (1,564 ICD-10 codes classified into 81 EDSCs categories) within 9 days of ED discharge. These codes were chosen by expert consensus; a panel of 4 emergency physicians (LB, AS, JA, ML) and 1 hospitalist (JF) reviewed 13,539 ICD-10 principal diagnosis codes on return visits with admission. The original definition of EDSCs excluded major injuries, presuming that repeat injury-related encounters were due to subsequent injuries rather than diagnostic errors on the index visit. A sensitivity analysis reclassified major injuries as EDSCs and thus included them in the calculation of potential major diagnostic error.

Of 24,122,318 ED discharges among older adults in 2022-2024, 4.0% had a return visit with admission for any reason. Return admissions for a non-injury EDSC occurred for 1.12% of ED discharges and 0.54% were followed by beneficiary death without a return admission. The estimated incidence of potential diagnostic error among older Medicare beneficiaries, the composite of death or return for an EDSC within 9 days was 1.66%. When we included major injuries in the definition of EDSCs (4,439 additional ICD10 codes), the estimated composite incidence of potential major diagnostic error was 1.88%.

Among older Medicare beneficiaries discharged from the ED in 2022-2024, between 1.7%-1.9% experienced a potential major diagnostic error, as defined by death after discharge or admission for an EDSC within 9 days. This incidence is below the commonly cited 2% post-test probability threshold thought to balance the harms of over-testing and treatment with those of a missed serious diagnosis for several diseases.