Table 3 Data health economic evaluation of drug use prevention would require, in addition to Table 2

Intervention costs*: direct costs of employees and materials and buildings:

   - Wages of employees and the amount of time spent on the intervention

   - Materials (re-usable/non re-usable, e.g. buildings, transport, didactic material) and attributable costs (distinguishing between fixed and variable costs)?

Direct treatment costs*: direct medical costs for treatment of symptomatic (physical and psychical) health problems related to different levels of use.

Indirect productivity costs: impact of the different levels of drug use on

   - Absenteeism as a consequence of morbidity

   - Decreasing personal development and level of productivity

   - Unemployment

Indirect 'control' costs

   - repressive and (secondary) preventive means to deal with social trouble (e.g. police activities, social workers, prisons,...)

▪ linearly related to the number of users

▪ non-linearly related to the number of users