Accuracy of data routinely collected by Australian hospitals for identifying infective endocarditis, causative organisms and clinical outcomes: a diagnostic accuracy study.

BACKGROUND

Infective endocarditis (IE) is a life-threatening condition, and the surveillance of the incidence is important for monitoring disease trends. Administrative data routinely collected by hospitals offer a feasible and inexpensive method for surveillance of patients with IE, yet the accuracy of coding of IE, causative organisms and outcomes is uncertain.

AIM: To evaluate the diagnostic accuracy of routinely collected Australian hospital administrative data for identifying IE, causative organisms and selected clinical outcomes.

METHODS

Using a cross-sectional design, we included all hospitalisations with International Classification of Diseases, 10th revision, Australian Modification (ICD10-AM) codes for IE from 1 January 2020 to 30 June 2023 at a quaternary referral centre. IE cases not captured by coding were ascertained by reviewing clinical data sources (echocardiogram reports, cardiothoracic surgical and device implantation registries and an IE biobank). We used a definite, possible or pathological diagnosis of IE as per the European Society of Cardiology (ESC) Modified criteria for IE as the reference standard for diagnosing IE.

RESULTS

We identified 353 hospitalisations with principal or secondary ICD10-AM diagnosis codes at discharge. Of these, 313 patients had IE as per the ESC Modified criteria. A further 51 patients (14%) with IE meeting the ESC modified criteria = were found not captured by coding during the same period. ICD10-AM codes for IE had an overall sensitivity of 0.86 (95% confidence interval (CI) 0.82-0.90), specificity of 1.00 (95% CI 1.00-1.00), a positive predictive value of 0.89 (95% CI 0.85-0.92) and a negative predictive value of 1.00 (95% CI 0.99-1.00). Coding identified the causative organism with an overall sensitivity of 0.77 (95% CI 0.72-0.81) and specificity of 1.00 (95% CI 1.00-1.00), with high accuracy for the most common organism, Staphylococcus aureus (sensitivity 0.88, 95% CI 0.80-0.93; specificity 0.95, 95% CI 0.89-0.98). Coding demonstrated high accuracy for detection of in-hospital deaths (sensitivity 0.91, 95% CI 0.75-0.98; specificity 1.00, 95% CI 1.00-1.00) and surgical management (sensitivity 0.91, 95% CI 0.86-0.94; specificity 1.00, 95% CI 1.00-1.00) with lower sensitivity and specificity for other outcomes.

CONCLUSION

ICD10-AM codes offer reasonable sensitivity and excellent specificity for the diagnosis of IE, common organisms and selected clinical outcomes and can be utilised for surveillance of IE.