Aura 2016: first Australian report on antimicrobial use and resistance in human health

5.1 Antimicrobial use

Data is available for comparison from a range of countries, including England, Scotland, Canada, the United States, Sweden, Denmark, the Netherlands and Norway. There is also a Europe-wide program, European Surveillance of Antimicrobial Consumption Network (ESAC-Net), which publishes annual data from 28 European countries. Each country has chosen to report using specific, and often different, measures. The most widely used, and the one preferred by ESAC-Net, is defined daily doses (DDDs) per 1000 inhabitants per day. Some countries also report data on the number of dispensed prescriptions per 100 or 1000 inhabitants; this is the only information available from the United States.

Many contributing countries are able to capture all, or almost all, of the prescribing data to generate these statistics. Where data is not available, sophisticated algorithms have been developed to extrapolate from large samples. Nevertheless, factors in individual countries make the comparisons indicative rather than absolute. In Australia, data on private prescriptions is not captured; in 2011, private prescriptions were estimated to contribute an additional 5% to antimicrobial use (AU).

A notable variation between countries is whether they report on the ‘antimicrobial’ methenamine (called hexamine hippurate in Australia). This is not a true antimicrobial agent, but a prophylactic agent used for recurrent urinary tract infections. Many countries choose to omit this agent, even though it is classed as a systemic antimicrobial (J01 class) under the Anatomical Therapeutic Chemical (ATC) system and has a DDD. In some countries, it can account for 5% of all prescribing. Methenamine is included in the Australian statistics. Australia also reports data on topical AU in the community, but all of the following comparisons are for agents in the J01 ATC class.

Community use

AU is higher in the Australian community than in many other countries. Figure 5.1 highlights the comparison with European countries based on DDD/1000 inhabitants/day – Australia ranks between the fifth and sixth highest in this group.

AU is higher in the Australian community than in many other countries.

Figure 5.1 Comparison of community antimicrobial use in Australia and 28 European countries, 2014

Sources: Pharmaceutical Benefits Scheme (Australia); European Surveillance of Antimicrobial Consumption Network (Europe)

Figure 5.2 shows a more detailed comparison with four northern European countries, England and Canada. These countries have been selected because they have readily accessible and comparable data. AU in the community in Australia is higher than in any of these countries.

Figure 5.2 Comparison of community antimicrobial use in Australia and other similar countries

Sources: Pharmaceutical Benefits Scheme (Australia); CIPARS (Canada); DANMAP (Denmark); ESPAUR (England); NethMAP (Netherlands); SWEDRES (Sweden)

Figure 5.3 compares the volume of prescriptions with one northern European country, two parts of the United Kingdom, Canada and the United States. When controlled for population, Australia’s AU is higher than all of these countries.

Figure 5.3 Comparison of community antimicrobial use in Australia and other countries

Sources: Pharmaceutical Benefits Scheme (Australia); CIPARS (Canada); ESPAUR (England); SAPG (Scotland); SWEDRES (Sweden); NARMS (United States)

Notable differences also exist between Australia and other countries in the patterns of AU in the community (Figure 5.4). Compared with Scandinavian countries, Australia uses fewer narrow-spectrum penicillins (β-lactamase-sensitive penicillins; ATC class J01CE) and a far greater proportion of β-lactamase inhibitor combinations and cephalosporins. The Netherlands is similar to Scandinavia, apart from having similar use of β-lactamase inhibitor combinations to Australia. Australia uses far fewer fluoroquinolones than comparator countries – this stems from the conservative restrictions placed on their prescription under the Pharmaceutical Benefits Scheme (PBS) and the Repatriation Pharmaceutical Benefits Scheme (RPBS) in the 1990s. With the exception of fluoroquinolones, patterns of use in Australia are closer to those of Canada. Use of tetracyclines varies widely from country to country.

Australia uses far fewer fluoroquinolones than comparator countries – this stems from the conservative restrictions placed on their prescription under the PBS and the RPBS in the 1990s.

Figure 5.4 Patterns of use of antimicrobial classes in Australia and other countries

DDD = defined daily dose

Sources: Pharmaceutical Benefits Scheme (Australia); CIPARS (Canada); DANMAP (Denmark); NethMAP (Netherlands); NORM (Norway); SWEDRES (Sweden)

Hospital use

Data on AU in hospitals in 2013 or 2014 is available from the Netherlands, Norway, Sweden, Denmark, England and Scotland. All these countries have close to 100% data capture and very dominant to near-universal care in public hospitals. Data is also available from Canada in 2011, also with high capture (only 3 of 13 provinces and territories are excluded).

In Australia, the national coverage of the National Antimicrobial Utilisation Surveillance Program (NAUSP) was estimated using actual DDDs and occupied-bed days (OBDs) from all contributors for 2014, and the actual number of patient days and separations. Coverage was estimated at 57.4% capture of the national DDDs and OBDs. These estimates allowed comparison of Australian hospital AU data on a range of measures reported by other countries.

Two measures of comparison (DDD/1000 OBD and DDD/1000 inhabitants/day) are presented in Figure 5.5. For some countries, neither measure was available. The former statistic is more widely used for intercountry comparisons. The latter statistic allows comparison between use in hospitals and the community in each country.

Figure 5.5 Antimicrobial use by (A) occupied-bed days and (B) inhabitants in Australian hospitals and other countries

A



B

Sources: National Antimicrobial Utilisation Surveillance Program (Australia); CIPARS (Canada); DANMAP (Denmark); ESPAUR (England); NethMAP (Netherlands); SAPG (Scotland); NORM (Norway); SWEDRES (Sweden)

There are some caveats to interpretation of the data; therefore, any comparisons made here should be considered indicative rather than absolute. Importantly, hospital AU in Australia was extrapolated on an OBD basis from the NAUSP 2014 data set, which covered 57% of the national OBD data. Nearly all comparator countries had at least 90% data capture. There were also variable exclusions in each country, such as psychiatric and rehabilitation ‘hospitals’.

On an OBD basis, Australia’s hospital AU:

exceeded that of Sweden and the Netherlands

was similar to that in Denmark

was significantly lower than in England.

However, on a population basis, Australia’s AU was higher than that of the Netherlands, Norway, Sweden, Canada and Denmark, but lower than that of England and Scotland. Hospital use comprised approximately 11% of total AU in Australia, compared with a range of 8% in Canada, Norway and the Netherlands to 12% in Denmark.