Quality of outpatient antibiotic use in 2009 was compared between 32 countries by calculating the indicator values for 2009 for each of the 12 ESAC drug-specific quality indicators based on outpatient antibiotic use data expressed in defined daily doses per 1000 inhabitants per day (DID). For each of the indicators we grouped the 2009 indicator values into four quartiles.
To evaluate changes in quality between 2004 and 2009, based on their respective indicator values, countries were also grouped according to the quartile distribution of the 2004 indicator values. Only countries able to deliver data for both years were included in this analysis.