Background: Although systems to collect information about suspected adverse drug reactions (ADRs) were established in many countries and by the WHO in the 1960s, few studies have examined reported ADRs related to national income.
Objective: The aim of the study was to characterize ADRs reported to the WHO-ADR database, VigiBase™, and to relate data to national income.
Methods: We analysed ADR reports submitted to VigiBase™ from 2000 to 2009 with respect to reporting rate, age and sex of patient, type, seriousness and medications. Reports were also analysed with respect to national income level, classified in accordance with the World Bank definition: low, lower-middle, upper-middle and high.
Results: We analysed 1,359,067 ADR reports including 3,013,074 ADRs. Overall, 16% of reports were serious and 60% were reported for females. High-income countries had the highest ADR reporting rates (range 3-613 reports/million inhabitants/year) and low-income countries the lowest (range 0-21). Distribution of ADRs across income groups with respect to age group, seriousness and sex was non-significant. Overall, the majority of ADRs were reported for nervous system medications, followed by cardiovascular medicines. Low-income countries reported relatively more ADRs for antiinfectives for systemic use than high-income countries, and high-income countries reported more ADRs for antineoplastic and immunomodulating agents than lower-income groups.
Conclusion: This study showed that high-income countries had the highest ADR reporting rates and low-income countries the lowest, with large variations across countries in each group. Significant differences in ADR reporting rates were only found for ADRs of the type 'skin and subcutaneous tissue disorders' and for the therapeutic groups 'antiinfectives for systemic use' and 'antineoplastic and immunomodulation agents'. To strengthen ADR reporting rates, especially in low-income countries, more research is needed about the impact of organizational structures and economic resources of national pharmacovigilance centres and ADR reporting practices on the large variations in ADR reporting rates within income groups.