Comparison of seven electronic healthcare databases in eu countries using a standardized methodology; a descriptive study on the exposure to calcium-channel blockers (CCBS)

Background: Information on prevalence of CCB prescribing is scarce in the literature and differs considerably among European countries due to differences in type of data sources, time periods, population distributions, and methodology used. Objectives: To measure and investigate sources of variation in prevalence of CCB prescribing across seven European routine health care databases using a standardised methodology. Methods: We used seven electronic health record databases from Spain (BIFAP), the United Kingdom (UK; THIN, CPRD), Netherlands (Mondriaan AHC, NPCRD), Denmark (national prescription registry), and Germany (Bavarian Claims). Analyses on annual prevalence of CCBs (2001-2008) were stratified by sex, age, and CCB class ('with vascular effects' or 'with mainly direct cardiac effects'). Overall prevalences were age/sex-standardised to the European 2008 reference population. Results: For vascular CCBs the variation in prevalence decreased after standardisation and varied from 192 per 10,000 persons (Netherlands, NPCRD) to 393 per 10,000 in the UK (THIN) in 2001. Except for Spain, the prevalence of vascular CCBs increased from 2001 to 2009 by 47%/year (Netherlands, AHC) to 89%/year (Denmark). Cardiac CCB use was lower, 87 per 10,000 (NPCRD) to 154 (AHC) in 2001 and then decreased in all databases by 4.5%/year (UK, THIN) to 42%/ year (Denmark) in 2009. Any CCB use was negligible up to age 40 and increased for both sexes up to 2,739 per 10,000 at age 80-89 years in BIFAP. Conclusions: We showed that from 2001 to 2009, the prevalence of CCB prescribing differs in five EU countries using a standard methodology, despite the convergence seen after standardisation to a reference population. Overall findings show that prescribing of CCBs with direct cardiac effects decreased whereas, except in Spain, CCBs with vascular effects increased.