Explanation of variable:
Type of substance
In case of abuse, it should be defined what is considered as abuse, Eg. :
Alcohol: For men: An intake of >25 alcohol containing units a week. For women: An intake of > 20 alcohol containing units a week.
Format of data:
Character:
- ALCO = Alcohol
- IDU = Intravenous Drugs
- NDU = Non-injecting Drugs
- SMK = Smoking
- SMKD = Ever smoked