24 Chapter 2 Country selection We analysed data on antibiotic prescriptions from European countries because they collect and report their data in a standardized format through the European Centre for Disease Prevention and Control (ECDC) (11). For a country to be included in the study, GPs had to act as a ‘gatekeeper’ in the healthcare system, defined as a compulsory GP referral to access most types of specialist care except in case of emergency (S2) (12). These countries generally have lower levels of antibiotic prescriptions (13). Data extraction Antibiotic prescriptions The volume of antibiotic prescriptions per country was extracted from the ECDC open source antimicrobial consumption database (ESAC-NET) on 15 March 2022 (11). The volumes were represented in DDD per 1000 inhabitants per day for the years 2011 through 2020. DDD is defined as the assumed average maintenance dose per day for a drug used for its main indication in adults (14). To translate absolute volumes of prescribed antibiotics to a value representing the ASP in a country, we calculate and present the Antibiotic Spectrum Index (ASI) as a proxy indicator for ASP (15). The ASI incorporates the volume of used antibiotics and their activity against micro organisms, expressing these through an index number representing the spectrum of micro organisms that are susceptible to that drug (S3a). The ASI assigns numerical values for an antibiotic that has activity against 1 or more of 13 categories of pathogens, with lower values indicating narrow-spectrum agents and higher values broader-spectrum agents. The ECDC website does not provide data on individual antibiotics, instead providing information per Anatomical Therapeutic Chemical Classification System (ATC) fourthlevel chemical subgroup. Antibiotics in a subgroup are effective against the same micro organisms and have an equal index number (15). Only antibiotics in ATC subgroups macrolides and quinolones have different index numbers. Hence, a mean ASI had to be calculated for these subgroups. For antibiotics lacking a reported ASI, one was calculated using the method proposed by Gerber et al. on the basis of their activity against microorganisms (15). In total, 13 antibiotics were not indexed in the ASI (S3b) and were indexed instead by our research group. The ATC subgroup J01RA, combinations of antibacterials, was excluded from the ASI analysis because it was not possible to calculate an average. The cumulative ASI per ATC subgroup was calculated by multiplying the volume of antibiotic prescriptions in DDD per 1000 inhabitants by the ASI number for that
RkJQdWJsaXNoZXIy MTk4NDMw