Comparison of hospital episodes with 'drug-induced' disorders and spontaneously reported adverse drug reactions

Aims To compare Hospital Episode Statistics for 'drug-related' admissions with spontaneously reported adverse drug reactions (ADRs) using UK Yellow Card data for the period 1996-2000. Methods This was a descriptive study for which we matched the relevant datasets in respect of time, place, evidence of hospitalization and disease terminology. The principal outcome was the ratio of ADRs leading to hospitalization which had been reported spontaneously during the whole study period. Results Twenty types of ADR were included and between them there was a wide spread of overall ratios (range 0-130%). The general tendency was for under-reporting on Yellow Cards but for ADRs with a fatal outcome this appeared to be less (range 7-168%). Conclusions This study provides some broad indications of the degree of under-reporting of ADRs that occurs despite a clinical diagnosis of a serious ADR being made and recorded.