Using a capture–recapture method to assess the frequency of adverse drug reactions in a French university hospital

Abstract

There is evidence that different methods used to identify and quantify adverse drug reactions (ADR) in hospitals are not exhaustive (spontaneous reporting or computerized medical databases). The combination of these different sources of data could improve knowledge about ADR frequency in hospitals. The aim of this study was to estimate the incidence of serious ADRs handled in medical wards of a French university hospital using data from the Programme de Medicalization des Systemes d'Information (PMSI) and spontaneous reports recorded in the French Pharmacovigilance Database. The study period was the first semester of 2001. From PMSI, all hospitalization summaries including an ICD-10th code related to a potential ADR were selected. From the French Pharmacovigilance Database, all serious ADRs which occurred during the study period and were reported by physicians working in the University Hospital were collected. After identification of common cases, the capture-recapture method was applied in order to estimate the real number of ADRs occurring during the first semester of 2001. From PMSI, we identified 274 different hospital stays related to an ADR. Out of 241 reports selected from the French Pharmacovigilance Database, we retained 151 ADRs for analysis. Fifty-two ADRs were common in the two databases, giving an estimated number of serious ADRs of 796 [95% confidence interval (CI) 638, 954], corresponding to 2.9% of inpatients (95% CI 2.3, 3.5). This study shows the lack of exhaustiveness of ADR reporting whatever the sources of data and underlines the interest of merging data from different databases to identify fully the real impact of ADR in hospitals.