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Measurement of Antibiotic Consumption

Learn more about measurement of quantity and quality of antibiotic consumption.

Dr Khalid Eljaaly describes how there are several methods for measuring the quality of antibiotic prescribing and interventions by the antibiotic stewardship program and health care professionals.

Without electronic prescribing, one relatively easy way to measure quality is by using Point Prevalence Survey (PPS).

One way to prioritise targets for improvement is to follow the Model for Improvement. Three questions need to be answered:

  • What are we trying to accomplish?
  • How will we know that a change is an improvement?
  • What changes we can test that will result in an improvement?

Quality Measures

Structural Measures evaluate whether governance structures are in place for the antibiotic stewardship program such as availability of formal stewardship team, meeting regularly, and inclusion of certain staff into the stewardship team.

Process Measures evaluate systems in place for the program such as percentage of adherence to a documentation policy, intervention, or guideline, and percentage of recommendation acceptance.

Examples of Outcomes Measures are clinical cure, mortality, length of stay, C. difficile infections, and antibiotic resistance.

Quantitative Measures

The preferred numerators for measuring antibiotic quantity are defined daily doses (DDDs) and days of therapy (DOT). Examples of other quantitative measures are prescribed daily dose, length of therapy, number of tablets, and number of prescriptions.

DDD is the number of grams dispensed divided by the WHO DDD. The WHO DDD is the assumed average maintenance dose per day for a drug used in its main indication in adults.


The DDD should be differentiated from another metric called prescribed daily dose (PDD), which is the average dose prescribed according to a representative sample of prescriptions. The PDD can be calculated from studies of prescriptions or medical or pharmacy records. PDD should be related to the indication for which the antibiotic is prescribed. The number of prescriptions and physical units (e.g., grams) can be used too and are easy to obtain.

DOT is the number of days a single antimicrobial is administered regardless of the number of doses administered or dosage strength.

DDDs are discussed further in the Antimicrobial Stewardship: Managing Antibiotic Resistance FutureLearn course. BSAC also has a course on Point Prevalence Surveys which provides further detail on their use and practical guidelines.

Do you currently carry out any quantitative measures of antibiotic consumption in your healthcare setting?

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Antimicrobial Stewardship for the Gulf, Middle East and North Africa

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