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.