Material and methods

Drug consumption statistics
Structure of the ATC system
Calculating drug consumption

Drug consumption statistics

The sales figures are based on the sales of the three largest drug wholesalers in Finland, which together account for nearly 100% of total drug sales. The remainder (about 1%) is mainly comprised of hospital sales.

The wholesale value can be approximated to retail prices by multiplying it by 1.6. VAT (8%) is not included in the wholesale figures.

In the statistics drugs are sorted using the latest Anatomical Therapeutic Chemical (ATC) classification. See also www.whocc.no

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Structure of the ACT system

In the Anatomical Therapeutic Chemical (ATC) classification, the drugs are divided into different groups according to the organ or system on witch they act and their chemical, pharmacological and therapeutic properties.

Dugs are classified in groups at five different levels. The drugs are divided into fourteen main groups (1st level), with one pharmacological /therapeutic subgroup (2nd level). The 3rd and 4th levels are chemical/pharmacological/therapeutic subgroups and the 5th level is the chemical substance.

For example, the ATC category of simvastatin (C10AA01) is as follows:

C Cardiovascular system
(1st level, anatomical main group)

C10 Serum lipid reducing agents
(2nd level, therapeutic subgroup)

C10A Cholesterol- and triglyceride reducers
(3rd level, chemical/pharmacological/therapeutic subgroup)

C10AA HMG-CoA reductase inhibitors
(4th level, chemical/pharmacological/therapeutic subgroup)

C10AA01 Simvastatin
(5th level, chemical substance)

(Linkki www.whocc.no)

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Calculating drug consumption

Drug consumption is given as defined daily doses (DDD). A DDD is defined as the assumed average maintenance dose per day for a drug used on its main indication in adults.

The calculations are based on the volume of sales to pharmacies and hospitals by wholesalers and on the assumed average dose per day for each drug. Consumption is usually expressed as a number of DDDs per 1 000 inhabitants and per day. The following example shows how simvastatin consumption is calculated:

DDD of simvastatin 0.015 g
Consumption 583,579.5 g/year
Population 5,212 x 1,000

1. Total consumption of simvastatin in grams is first converted into DDDs using the following equation:

583,579.5 g/0.015 g = 38,905,301 DDD

2. The number of DDDs is then adjusted to the population and the number of days per year.

38,905,301 DDD = 20.45 DDD/1,000 inhabitants/day
5,212 x 365

The figure of 20.45 DDD/1 000 inhabitants/day indicates how many people (in this case 20.45) per 1 000 of the population may in theory have received that standard dose (15 mg) of simvastatin.

When interpreting the figures, it should be remembered that the DDD is only a technical expedient and is not necessarily equal to the actual dose. The DDD of a drug can be difficult to establish, as the drug dose depends on indications, individuals and therapeutic practices. When using sales figures provided by wholesalers, it is worth noting that some drugs sold may still be unused, either in dealer stores or in patient homes. The DDD figure is generally calculated in relation to the total population, although drug use may be concentrated in certain age groups or a particular sex.