Table 1.

Main advantages and disadvantages of AMR indicators

Type of indicator	Description	Advantages	Disadvantages
Single indicator	One combination of microbe, antimicrobial class and source of isolate	High level of detail Investigation of the association with AMC data is possible Interpretation is straight‐forward Data are available from current monitoring Useful as basis for design of interventions Easier to detect changes in a single sector	Poor overview on overall resistance situation for different antimicrobials and, for animals, in different species Influenced by minor changes in a single sector If only few antimicrobials are monitored, a shift to alternative antimicrobials may be provoked which will not be detected in the monitoring Multitude of information can be time‐consuming to analyse
Summary indicator	Resistance or susceptibility level obtained as a combination of several microbes and/or resistance to antimicrobials and/or sources of isolates, possibly adjusted for populations	Reduces complexity by summarising data Easy to communicate Less influenced, than single indicators, by minor changes in resistance to individual antimicrobial classes in specific sectors Useful for monitoring general long‐term trends in the resistance situation in the different sectors	Using a limited number of summary indicators may not cover the whole resistance situation Proportions of resistant bacteria may not be directly comparable between different antimicrobial classes and different species Combining data may lead to the indicator failing to detect change in AMR Opposing trends in individual components might cancel each other out and remain unnoticed Effects of specific interventions on one antimicrobial class or in one species cannot be monitored effectively Less useful than single indicators as a basis for design of specific interventions
Composite indicator	Overall indicator obtained as a combination of several microbes and/or resistance to antimicrobials and/or sources of isolates, and weighting resistance data with data from other sources such as usage data or public health relevance	Good for monitoring general trends because it is a better representation of the overall situation Allows comparison of the resistance situation between different sectors Less influenced, than single indicators, by minor changes in resistance to individual antimicrobial classes in specific sectors	Interpretation of these indicators is complex Choice of weighting factors has a major influence on the validity of the indicator Combining data may lead to the indicator failing to detect change in AMR Opposing trends in individual components might cancel each other out and remain unnoticed Effects of specific interventions on one antimicrobial class or in one species cannot be monitored effectively Not useful as basis for design of specific interventions