Comparison of methods to correct the miscounting of multiple episodes of care when estimating the incidence of hospitalised injury in child motor vehicle passengers.

This study evaluates the performance of different case selection criteria to account for multiple episodes of care when estimating the hospitalisation rate due to road trauma amongst children. The internally linked NSW Inpatient Statistics Collection (ISC) dataset for the period between 1st July, 2000 and 30th June, 2003 was used to identify the "single" episode of care for each hospitalised child motor vehicle passenger residing in NSW. We used two hospitalised injury definitions of a case based on (1) all-diagnoses and (2) principal diagnosis only. We then developed case selection criteria, based on (a) linkage methods only available from linked ISC datasets; (b) selected variables available in both the linked and unlinked ISC datasets, to exclude repeat episodes of care for an injury. Changes in the estimated hospitalisation rate, and sensitivity and specificity, were calculated for each selection criteria compared to the findings from linkage methods as the "gold standard". None of the correction methods for multiple episodes of care was clearly superior in terms of incidence estimation, sensitivity, and specificity concurrently. However, the correction criterion which is optimal may vary depending on different study objectives and different types of hospitalised injuries.