Guidelines for ATC classification and DDD assignment - WHOCC

A. Drug utilization
The ATC/DDD system can be used for collection of drug utilization statistics in a
variety of settings and from a variety of sources.
Examples are:
- Sales data such as wholesale data at a national, regional or local level.
- Dispensing data either comprehensive or sampled. Computerised pharmacies can
easily collect data on drugs dispensed. Alternatively, sample data can be
collected manually. Reimbursement systems, which operate in a number of
countries at the national level provide comprehensive dispensing data down to
the individual prescription level, as all prescriptions are submitted and recorded
for reimbursement. This is generally called “claims” data. Similar data are often
available through health insurance or health maintenance organisations.
These databases can sometimes allow collection of demographic information on
the patients, and information on dose, duration of treatment and co-prescribing.
Less commonly, linkage to hospital and medical databases can provide
information on indications, and outcomes such as hospitalisation, use of specific
medical services, and adverse drug reactions.
- Patient encounter based data. This is usually collected by specially designed
sampling studies such as those carried out by market research organisations.
However, increasing use of information technology at the medical practice level
will make such data available more widely in the near future. These methods
have the advantage of potentially providing accurate information on Prescribed
Daily Doses, patient demographics, duration of therapy, co-prescribing,
indications, morbidity and co-morbidity, and sometimes outcomes.
- Patient survey data. Collection of data at the patient level can provide
information about actual drug consumption and takes into account compliance in
filling prescriptions and taking medications as prescribed. It can also provide
qualitative information about perceptions, beliefs, and attitudes to the use of
medicines.
- Health Facility data. Data on medication use at all the above levels is often
available in health care settings such as hospitals and health centres at regional,
district, or village level.
33