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On behalf of the ESAC Management team
Laboratory of Microbiology
University of Antwerp
Resistance to antimicrobials has become a major public health concern, and it has been shown that there is a relationship, albeit complex, between antibiotic resistance and consumption. Several antibiotic resistance surveillance programmes are operational in Europe, but a programme for the collection of antibiotic consumption data has been lacking. On 15 November 2001, a Council recommendation on the prudent use of antimicrobial agents in human medicine (2002/77/EC)(1) stated that concerted action is necessary at the Community level to contain the problem of antimicrobial resistance and that specific strategies should be used to collect data on use of antimicrobial agents, both in the community and in hospitals. At the same time, the ESAC project (European Surveillance of Antibiotic Consumption), funded by DG/SANCO of the European Commission (2001/SID/136), was launched as an international network of surveillance systems.
During the pilot phase of this project (November 2001–October 2003), actions were taken to harmonise the collection of antimicrobial consumption data in all participating countries. In most European countries, some information on the consumption of antimicrobials exists at the national level. Large differences can be observed, however, in the structure and the accessibility of these databases. Moreover, in order to compare antimicrobial consumption at the EU level, internationally applicable methods need to be established, including both a uniform classification system and a common unit of measurement. Standardised national data will be assembled in a European database for comparison of antibiotic use in relation to antibiotic resistance patterns and socioeconomic and general health parameters.
First results of the ESAC retrospective data collection
During the pilot phase of the ESAC project, the ESAC management team has established a network of dedicated experts in 15 EU Member States, 11 applicant countries and five others. Retrospective data for ambulatory care and hospitals were collected for the period 1997–2001 using the ATC/DDD classification (WHO, version 2002). Retrospective data from 27 countries are available. Ambulatory care data are available from 24 countries, and hospital care data from 23 countries.
The validity of the data collection process was evaluated by assessing coverage bias in census data, sampling bias in sample data, bias by unaccounted over-the-counter sales or parallel trade or inadequate registration of nonreimbursed antibiotics, and finally bias by shifts in the mix of consumption between ambulatory care and hospital care.
Antibiotic consumption in hospital care
Hospital care use data were provided by 23 countries. Two were not comprehensive for 2000 or 2001 (Italy, Portugal); seven were based on a limited sample, not representative for the whole country. Data from 14 countries could be used to estimate the exposure of the country population. In all but one country (Belgium), hospital care data were collected from the distribution chain, mostly at the individual hospital care level.
Eleven countries were able to deliver valid HC data for the whole period of observation (Belgium, Denmark, Finland, France, Greece, Luxembourg, Spain and Sweden in the EU, and Malta, Poland and Slovenia among the applicant countries).
A wide variation in the share of hospital care within the total national antibiotic consumption could be observed between different European countries, ranging from 5% (Slovakia) to 17% (Finland). This could be partly explained by substantial variation between the methods to separate ambulatory care from hospital care data. Particularly in Finland, the separation between ambulatory care and hospital care was problematic, causing an overestimation of the hospital consumption.
In hospital care, a wide variation in the total use of penicillins, cephalosporins and quinolones as well as within the cephalosporin generations was observed. Similarly, the proportional use of hospital-specific antibiotics (eg, carbapenems, monobactams, aminoglycosides, glycopeptides) varied widely among European countries. For hospital care use, countries do not seem to cluster in regional consumption patterns. More detailed results and a description of the methodology are available on the ESAC website: http://www.esac.ua.ac.be
A prospective data collection system, based on a validated register of available antibiotic products linked to the correct ATC/DDD classification, will become effective by the end of 2003. Standardised national data will be assembled in a European database for international comparison of antibiotic use in relation to antibiotic resistance patterns, socioeconomic determinants and general health indicators. Aggregated results of the ESAC project will become available on the ESAC website. The database will be accessible for health authorities, scientists and the wider public to link utilisation data to resistance patterns and to assess the impact of intervention strategies at the community and hospital level.
Quantitative consumption data will be complemented with a database offering an inventory of projects focused on antibiotic consumption (published research as well as ongoing projects).
The ESAC project has been successful in its retrospective data collection. Further efforts are needed to consolidate and enhance the quality of the surveillance of antibiotic consumption, so as to achieve a better understanding of the development of antimicrobial resistance and to foster appropriate prescribing. Specifically for hospital care use, a close collaboration with the hospital pharmacists is crucial to enlarge the sample size of individual hospitals involved in the data collection system of ESAC.