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Measure  –  Consumption


Here you find guidance, methods and tools to measure antibiotic consumption in humans, focusing on healthcare and community settings.

Classification of medicines

The Anatomical Therapeutic Chemical (ATC) classification system, coordinated by the WHO Collaborating Center for Drug Statistics Methodology, is the most widely used classification system for drugs in humans. The ATC divides drugs into different groups according to the organ or system on which they act and/or their different characteristics. Each drug is assigned a Defined Daily Dose (DDD), or the assumed average maintenance dose per day for a drug used for its main indication in adults. Use of the DDD system allows standardization of drug groupings and a stable drug utilization metric to enable comparisons of drug use between countries, regions, and other health care settings, and to examine trends in drug use over time and in different settings.

Understanding data on antibiotic consumption

Consumption is often converted to defined daily doses (DDD) per 1,000 inhabitants per day. This allows for estimation of the proportion of the population in defined area who are treated daily with a particular medication. In hospital settings use is often presented as DDDs/100 bed-days

Example for converting consumption data into DDD/1000 inhabitants/year for comparison:

Obtain the quantity of antibiotics consumed/procured within the time frame of interest. In the example below we will use one year.

  • Note the number of units e.g. (tablet, capsules or injections) and the strength.
    • Example: gram (g)/milligram(mg)
  • Multiply the number of units by the strength of the dose to obtain the total quantity.
    • Example: 80,0000 tablets of Cefuroxime*500 mg=40,000000 mg=40,000g
  • Divide the total quantity by the assumed DDD of Cefuroxime. Note that oral cefuroxime’s DDD assigned by the WHO = 0.5g.
    • Example: 40,000/0.5=80,000 DDD
  • Divide the total quantity by the population of interest. Example Dormaa Ahenkro in Ghana with a population of 100,000 inhabitants).
    • Example: 80,000/100000 inhabitants=0.8 DDD/inhabitant/year
  • Convert to 1000 inhabitants per year.
    • Example: 0.8DDD*1000=800 DDD/1000 inhabitants/year
  • You may convert this to 1000 inhabitants/day by dividing by 365 days

Antibiotic consumption in health care settings

Information on antibiotic consumption at the health care facility can be utilized to monitor consumption levels within a health care facility over time, compare consumption to other facilities, or evaluate the effect of an intervention.

Data on antibiotic consumption and prescription patterns can be gathered from for example:

  • The ministry of Health
  • Wholesalers drug records
  • Hospital medical stores
  • Pharmacy sales records, pharmacy stock and dispensing logs
  • Patient medical records

Antibiotic prescribing data can be extracted from outpatient and inpatient prescription forms. This process can be facilitated through the use of computerized records, however in the absence of electronic databases, relevant prescribing data can be manually extracted from patient records or retrieved at dispensing points.

Point prevalence studies

Point prevalence studies are a way to collect data at a specific point or period of time. The point of time can be a single day or continuously during a period of time. The European Center for Disease prevention and Control (ECDC) provides protocols and materials for point prevalence surveys on antibiotic use in European countries, that can be used as a starting point when developing protocols for other settings (see resource table below).

Combining interviews with lab tests to understand use in Ghana:

Widespread prevalence of antimicrobial resistance in important pathogens for both community and hospital acquired infections have been reported in GhanaIn Ghana data on the quantities of antibiotics sold are difficult to obtain due to weak systems for regulations of medicines. An investigation on the use of antibiotics was conducted by interviewing patients, asking if they had used antibiotics, and then comparing their answers to the prevalence of antimicrobials measured in their urine. The researchers detected antibiotics in urine samples more frequently than was expected from the use reported by patients.

In Ghana, literacy rates are low and participants may have had difficulties identifying drugs they used as antibiotics, however the patients may have also unknowingly been exposed. Self-medication is often practiced in Ghana, including treatment with traditional herbal medicines, which are frequently laced with antibiotics. The presence of antibiotics could also be caused by chronic exposure as through drinking water, milk, or tea. It is important to consider and identify all sources of antibiotic exposure, as all use of antibiotics can lead to the development of resistance. This study is an example of a novel method to investigate use.

Antibiotic consumption in the community

Investigating the provision and consumption of antibiotics in communities can help to identify the reasons for inappropriate use, and gain insight into the various channels through which people in communities obtain antibiotics. This may include consumption of medicines that were intended for use in animals and vis-versa. Furthermore, it can lead to learning about people’s beliefs of drug safety and efficacy, their self-medication practices, and the extent to which they follow the advice of prescribers or dispensers. Non-compliance with prescription, when people do not do what health workers advise them, include that they fail to purchase the drug that is prescribed, stop taking the prescribed drug or take the wrong dosage. This information is needed for the development of strategies to improve the rational use of antibiotics..

Sources for information

Antibiotics found in the community may have been prescribed or dispensed in a health care facility or purchased at a pharmacy or drug outlet or street vendor. The quantity of antibiotic consumption in the community can be investigated using information from for example:

  • Invoices
  • Stock or dispensing records
  • Patient medical records
  • Observational studies
  • Surveys or exit interviews at pharmacies or other drug outlets

Actual utilization can be assessed by counting leftover pills, survey rubbish bin for empty drug packages or performing household surveys.

Interviews as a tool to measure antibiotic use in the community

Patients and consumers can be interviewed when leaving health care facilities, pharmacies and other dispensaries about the services, treatment recommendations, or information they received regarding antibiotics. Consumers can also be interviewed in their home, where they are likely to consume the antibiotics purchased. Examples of topics that a questionnaire could include are :

  • Types of antibiotics available/ being purchased
  • Medical problem for which antibiotics are purchased
  • Prices of the antibiotics
  • Source of advice on the purchase
  • Treatment taken before buying antibiotics
  • Ideas about the correct use of antibiotics

Interviews provide insight into antibiotic use

A study in Egypt measured antibiotic consumption by interviewing pharmacists, sale representatives and customers during one day in different local pharmacies and non-pharmacy outlets. In Vietnam a similar interview based study was conducted. The authors used exit interviews for measuring antibiotic purchased by customers. The table below provides more information about using interviews to measure antibiotic use in the community.

Resources below have been divided into the following tables:

  • One Health resources
  • Health care setting
  • Community setting
  • Databases and reports

Selected Resources

One Health resources

Resource Description
ECDC, EFSA and EMA Joint Scientific Opinion on a list of outcome indicators as regards surveillance of antimicrobial resistance and antimicrobial consumption in humans and food-producing animals Indicators: Suggestion of outcome indicators with a ‘One Health’ perspective for monitoring progress of surveillance of antimicrobial resistance and antimicrobial consumption in humans and food-producing animals, with methodology for how indicators were selected, and examples of calculation of indicators. Established by European health and food safety agencies.

Health care setting

Resource Description
Workbook tool & report template from WHO/SEARO for undertaking a situational analysis of medicines management, including measuring antibiotic use in health care delivery in low and middle income countries. The website also provides result reports of situational analyses in South-East Asian countries.
Global Point Prevalence Survey on Antimicrobial Consumption and Resistance This open to join project monitors antimicrobial prescribing and resistance in hospital patients on all continents through a “one day survey” and helps design hospital interventions to promote prudent use. Hospitals are welcome to join survey and network (already more than 300 institutions from over 50 countries have participated). For documents such as protocols and data collection templates in different languages (incl. Spanish, French and Arabic) for personal use click here. A scientific article with results from the project has been published in the Lancet Global Health.
Protocol that provides methodology and data collection forms for performing point prevalence survey (PPS) of antimicrobial use in European hospitals. PPS survey validation protocol can be found here.
Protocol that provides methodology and data collection forms for point prevalence survey (PPS) of antimicrobial use in European long-term care facilities. PPS survey validation protocol can be found here.
AMC Tool: the antimicrobial consumption tool Tool: Computer tool for transforming antimicrobial consumption data from hospitals and the community to meaningful utilization rates (Defined Daily Doses (DDD) using the ATC/DDD index), also contains a user manual.
How to Investigate Antimicrobial Use in Hospitals: Selected Indicators Indicators: Manual that defines indicators to help assess the management and use of antibiotics in hospitals and provides tools and step-by-step instructions for designing and carrying out assessment activities. Also available in French and Spanish.
How to Investigate Drug Use in Health Facilities: Selected Drug Use Indicators Indicators: Manual that defines indicators that can describe the drug use situation in a country, region or individual health facility.
Antimicrobial Resistance, Antibiotic usage and infection control: A self-assessment program for Indonesian hospitals (PDF, 2MB) A self-assessment program regarding antibiotic resistance, antibiotic use and infection control for Indonesian hospitals. The program contains information on antibiotic resistance surveillance, standard operating procedures for collecting data on antibiotic use and provides example flow charts (as attachments) for quality assessment.
The Worldwide Antibiotic Resistance and Prescribing in European Children (ARPEC) point prevalence survey: developing hospital-quality indicators of antibiotic prescribing for children Indicators: Development of quality indicators of improved antimicrobial prescribing focusing specifically on hospitalized neonates and children worldwide. More information about the method can be found here.
WHO methodology for a global programme on surveillance of antimicrobial consumption (PDF, 1MB) Methodology: WHO methodology describing surveillance of antimicrobial comsumption; How to collect data, what data to collect and how to manage data.
Survey protocol in nationwide hospital point-prevalence surveys in Sweden, 2003-2010 Protocol/Template: The data collection form for a nationwide point-prevalence survey performed in Sweden during 2003-2010. The results were published in Eurosurveillance: Repeated nationwide point-prevalence surveys of antimicrobial use in Swedish hospitals: data for actions 2003–2010  .

Community setting

Resource Description
How to Investigate the Use of Medicines by Consumers Manual that provides a practical guide to the methods that can be used to investigate the use of medicines by consumers to identify problems, design interventions, and measure changes.
Community-Based Surveillance
of Antimicrobial Use and Resistance in Resource-Constrained Settings
Report on five pilot projects (PDF, 1MB)
Report on activities associated with the implementation of five pilot projects for community‐based monitoring of antibacterial medicine use and antimicrobial resistance in resource‐constrained settings. Chapters 2 to 6 contain the reports on each of the pilot sites, giving details of the methods used, the results obtained, and commentary on the problems encountered at each site.
WEPI – Web questionnaires for epidemiologists and health professionals Questionnaire template: A web based questionnaire tool for epidemiologists and health care personnel that can be used for surveys or interviews. The system allows for unlimited amount of questions and the web page also contains a practical video on how the tool can be used.
AMC Tool: the antimicrobial consumption tool Tool: Computer tool for transforming antimicrobial consumption data from the community to meaningful utilization rates (Defined Daily Doses (DDD) using the ATC/DDD index), also contains a user manual.
Antimicrobial Resistance Module for Population-Based Survey (PDF) This module generates household-level information on knowledge and behavior regarding antimicrobial medicines and raises awareness regarding resistance among communities.

Databases and reports

Resource Description
ECDC/EFSA/EMA joint reports on the integrated analysis of the consumption of antimicrobial agents and occurrence of antimicrobial resistance in bacteria from humans and food-producing animals (JIACRA reports) Report: Using existing data from Europe, ECDC/EFSA/EMA has made an integrated analysis of antimicrobial consumption and resistance to the same antimicrobials in bacteria from humans and animals.
Antimicrobial consumption interactive database (ESAC-Net) Database and reports: The European Surveillance of Antimicrobial Consumption Network (ESAC-Net) interactive database provides European reference data on antimicrobial consumption, both in the community (primary care sector) and the hospital sector. ESAC-Net yearly reports (starting from 2010) can be accessed here.
Resistance Map Database: ResistanceMap provides interactive charts and maps summarizing national and sub-national data on antimicrobial use and resistance around the world.
WHO Report on Surveillance of Antibiotic Consumption – 2016 – 2018 Early implementation Report from WHO presenting data from 2015 on the consumption of systemic antibiotics from 65 countries and areas. It describes the WHO methodology for data collection, including challenges and future steps in monitoring antimicrobial consumption.
Antimicrobial Medicines Consumption (AMC) Network. AMC data 2011–2014 (2017) Report presenting and analysing data on antimicrobial medicines consumption collected from non-European Union countries in the WHO European Region and Kosovo. It aims to support countries that are building or strengthening their national surveillance systems on AMC and to stimulate the sharing of data both within and between countries.
Country-specific reports: Canada; Denmark; the Netherlands; Norway; Sweden Reports: Country-specific annual reports on antibiotic consumption in humans (and in some cases animals). Click on the respective country to access the reports.

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