Diagnostic accuracy of ICD-9 code 780.2 for the identification of patients with syncope in the emergency department

Purpose Syncope is a common condition that affects individuals of all ages and is responsible for 1–3% of all emergency department (ED) visits. Prospective studies on syncope are often limited by the exiguous number of subjects enrolled. A possible alternative approach would be to use of hospital discharge diagnoses from administrative databases to identify syncope subjects in epidemiological observational studies. We assessed the accuracy of the International Classification of Diseases, Ninth Revision (ICD-9) code 780.2 “syncope and collapse” to identify patients with syncope. Methods Patients in two teaching hospitals in Milan, Italy with a triage assessment for ED access that was possibly related to syncope were recruited in this study. We considered the index test to be the attribution of the ICD-9 code 780.2 at ED discharge and the reference standard to be the diagnosis of syncope by the ED physician. Results The sensitivity, specificity, positive and negative predictive values of the ICD-9 code 780.2 to identify patients with syncope were 0.63 (95% confidence interval [CI] 0.58–0.67), 0.98 (95% CI 0.98–0.99), 0.83 (95% CI 0.79–0.87) and 0.95 (95% CI 0.94–0.95), respectively. Conclusions The moderate sensitivity of ICD-9 code 780.2 should be considered when the code is used to identify patients with syncope through administrative databases.