Epidemiology, mortality and miss rate of acute aortic syndrome in Ontario, Canada: a population-based study

Mortality and risk factors associated with misdiagnosis of acute aortic syndrome in Ontario, Canada: a population-based study

INTRODUCTION

Acute aortic syndrome (AAS) is a life-threatening aortic emergency. It describes three diagnoses: acute aortic dissection, acute intramural haematoma and penetrating atherosclerotic ulcer. Unfortunately, there are no accurate estimates of the miss rate for AAS, risk factors for missed diagnosis or its effect on outcomes.

METHODS

A population-based retrospective cohort study of anonymously linked data for residents of Ontario, Canada, was carried out. Incident cases of AAS were identified between 2003 and 2018 using a validated algorithm based on ICD codes and death. Before multivariate modelling, all categorical variables were analysed for an association with missed AAS diagnosis using χ2 tests. These preliminary analyses were unadjusted for clustering or any covariates. Finally, we performed multilevel logistic regression analysis using a generalised linear mixed model approach to model the probability of a missed case occurring.

RESULTS

There were 1299 cases of AAS (age mean (SD) 68.03±14.70, woman 500 (38.5%), rural areas (n=111, 8.55%)) over the study period. Missed cases accounted for 163 (12.5%) of the cohort. Mortality (non-missed AAS 59.7% vs missed AAS 54.6%) and surgical intervention (non-missed AAS 31% vs missed AAS 30.7%) were similar in missed and non-missed cases. However, lower acuity (Canadian triage acuity scale >2 (OR 2.45 95% CI 1.71 to 3.52) (the scale is from 1 to 5, with 1 indicating high acuity) had a higher odds of being a missed case and non-ambulatory presentation (OR 0.47 95% CI 0.33 to 0.67) and presenting to a teaching (OR 0.60 95% CI 0.40 to 0.90)) or cardiac centre (OR 0.41 95% CI 0.27 to 0.62) were associated with a lower odds of being a missed case.

CONCLUSIONS

The high rate of misdiagnosis has remained stable for over a decade. Non-teaching and non-cardiac hospitals had a higher incidence of missed cases. Mortality and rates of surgery were not associated with a missed diagnosis of AAS. Educational interventions should be prioritised in non-teaching hospitals and non-cardiac centres.

Can you accurately rule out acute aortic syndrome by restricting imaging of the aorta to the area of the patient's pain?

BACKGROUND

Acute aortic syndrome (AAS) is a life-threatening condition necessitating timely and accurate diagnosis for appropriate treatment. Currently, the only way to rule out the diagnosis is advanced imaging. The most accessible is computed tomography of the entire aorta. Most scans are negative, exposing patients to radiation, increased time in the emergency department (ED), and non-significant incidental findings. This study investigated whether restricting imaging to the area of aortic-related pain accurately rules out AAS.

METHODS

A health records review was conducted on consecutive cases from three academic EDs between 2015 and 2020. Data were extracted and verified from multiple sources. Participants included adults diagnosed with AAS based on radiological evidence. The diagnostic performance of the restricted imaging strategy was assessed; sensitivity and likelihood ratios with 95% confidence intervals were calculated.

RESULTS

Data from 149 cases of AAS were collected, with the majority presenting with chest pain (46%) or abdominal pain (24%). The restricted imaging strategy demonstrated a sensitivity of 96% (95% CI 91.4-98.5%) in ruling out AAS. In a subset of patients with systolic blood pressure > 90 mmHg and without aortic aneurysm/repair (n = 86), the sensitivity was 100% (95% CI 96-100%).

CONCLUSION

Restricting imaging to the area of pain in hemodynamically stable patients without known aortic aneurysm provides a highly sensitive approach to ruling out AAS.