Using the internet to research hidden populations of illicit drug users: a review.

AIMS To review the current research of hidden populations of illicit drugs users using web-based methods and discuss major advantages and disadvantages. METHODS Systematic review of 16 databases, including PubMed, PsycINFO (EBSCOhost), CSA Sociological Abstracts, Expanded Academic ASAP and Google Scholar. FINDINGS Substances researched were most commonly 'party/club drugs' (such as ecstasy) and cannabis. All of the studies reviewed concluded that the internet is a useful tool for reaching hidden populations, but is likely to impose some bias in samples. Advantages include: access to previously under-researched target groups; speed; international applications; increased ease of data entry; and improved confidentiality for respondents. The major disadvantage is a lack of representativeness of samples. CONCLUSIONS Internet research is successful at accessing hidden populations of illicit drugs users, when appropriately targeted and provides unprecedented opportunities for research across a wide range of topics within the addictions field. Findings are unlikely to be generalisable to the general public, but appropriate for describing target populations.