Guidelines for ATC classification and DDD assignment - WHOCC

F. Drug costs, pricing and reimbursement and cost-containment
Basing detailed reimbursement, therapeutic group reference pricing and other
specific pricing decisions on the ATC and DDD assignments is a misuse of the
system. This is because the ATC and DDD assignments are designed solely to
maintain a stable system of drug consumption measurement, which can be used to
follow and compare trends in the utilization of drugs within and across therapeutic
groups. None the less, drug utilization data have a central role in the quality of care
cycle and ATC and DDD methodologies can be helpful in following and comparing
trends in cost, but need to be used with caution.
The DDD is a technical drug use metric. DDDs do not necessarily reflect
therapeutically equivalent doses of different drugs and therefore cannot be assumed
to represent daily doses that produce similar treatment outcomes for all products
within an ATC category. Such estimates of therapeutic equivalence are very
difficult to establish, particularly to the precision usually required for pricing
decisions. DDDs, if used with caution can be used to compare, for example, the
costs of two formulations of the same drug. However, it is usually not valid to use
this metric to compare costs of different drugs or drug groups. The relationships
between therapeutically equivalent doses, the actual prescribed daily dose (PDD)
and DDD usually differ between drugs and, for the same drug, between countries.
Moreover, even though PDDs commonly change over time altering a DDD
complicates drug utilization research, hence there is a reluctance to alter a DDD.
Alterations are not made unless there is evidence that changes in PDD are large, or
there is some particular reason such as a change in the main indication. For these
reasons, DDDs are not suitable for comparing drugs for specific, detailed pricing,
reimbursement and cost-containment decisions.
Similarly, basing reimbursement and pricing comparisons on inclusion of drugs in
ATC groups is not recommended. The main indications for drugs (on which ATC
assignments are based) often differ widely between countries and, like the PDD,
can change over time. However, the ATC classifications can be useful when costs
need to be aggregated into drug groups or therapeutic areas to determine, for
example, to what extent increased costs can be attributed to increased use of a
therapeutic group over time.
G. Pharmaceutical marketing purposes
It is important to emphasise that the ATC classification does not necessarily reflect
the recommended therapeutic use in all respects. Therefore, the ATC system
should not be used as a tool for marketing purposes concerning efficacy,
mechanism of action or therapeutic profile in relation to other drugs.
37