Evaluating adverse drug event reporting in administrative data from emergency departments: a validation study

Background: Adverse drug events are a frequent cause of emergency
department presentations. Administrative data could be used to
identify patients presenting with adverse drug events for
post-market surveillance, and to conduct research in patient safety
and in drug safety and effectiveness. However, such data sources
have not been evaluated for their completeness with regard to
adverse drug event reporting. Our objective was to determine the
proportion of adverse drug events to outpatient medications
diagnosed at the point-of-care in emergency departments that were
documented in administrative data. Methods: We linked the records
of patients enrolled in a prospective observational cohort study on
adverse drug events conducted in two Canadian tertiary care
emergency departments to their administrative data. We compared the
number of adverse drug events diagnosed and recorded at the
point-of-care in the prospective study with the number of adverse
drug events recorded in the administrative data. Results: Among
1574 emergency department visits, 221 were identified as adverse
drug event-related in the prospective database. We found 15 adverse
drug events documented in administrative records with ICD-10 codes
clearly indicating an adverse drug event, indicating a sensitivity
of 6.8\% (95\% CI 4.0-11.2\%) of this code set. When the ICD-10
code categories were broadened to include codes indicating a very
likely, likely or possible adverse event to a medication, 62 of 221
events were identifiable in administrative data, corresponding to a
sensitivity of 28.1\% (95\% CI 22.3-34.6\%). Conclusions: Adverse
drug events to outpatient medications were underreported in
emergency department administrative data compared to the number of
adverse drug events diagnosed and recorded at the point-of-care.