Improving the reporting of adverse drug reactions - A cluster-randomized trial among pharmacists in Portugal

Background: Adverse drug reaction (ADR) reporting systems are the basic component for comprehensive postmarketing surveillance of the risk of drug-induced adverse effects. The aim of this study was to evaluate the effectiveness of educational outreach visits aimed at improving ADR reporting by pharmacists. Methods: The study population comprised all pharmacists working in a catchment area covered by Portugal's Northern Regional Health Authority. Using unequal randomization, four spatial-clusters were assigned to the intervention group (n = 342) and eleven to the control group (n = 1091). The intervention took the form of I-hour long educational outreach visits tailored to training needs detected in a previous study, with a 13- to 16-month follow-up period (March-June 2004 through June 2005). This study is registered as an international standard randomized controlled trial, number ISRCTN45894687. Results: At baseline, ADR reporting rates (per 1000 pharmacist-years) did not differ significantly between the intervention and control groups (32.28 vs 29.16). The adjusted increase in ADR reporting attributable to the intervention was 275.63 per 1000 pharmacist-years (95% CI 162.15, 389.12; relative risk [RR] = 5.87, 95% CI 1.98, 17.39). The intervention succeeded in multiplying the reporting rate of: serious ADRs, 10-fold (RR = 9.79; 95% CI 2.24, 42.66); unexpected ADRs, 4-fold (RR =4.41; 95% CI 1.11, 17.53); high-causality ADRs, 9-fold (RR = 8.67; 95% CI 2.12,35.42); and new drug-related ADRs, 9-fold (RR = 9.33; 95% CI 2.53, 34.40). While the greatest effect was registered during the first 4 months post-intervention, differences remained statistically significant for 8 months. Conclusions: Educational outreach visits improve ADR reporting by pharmacists in terms of quantity and relevance.