Transitions in the route of cocaine administration--characteristics, direction and associated variables.

AIMS: To examine transitions in the route of administration of cocaine and the variables associated with them.
DESIGN: A cross-sectional study undertaken between January 1996 and October 1997.
SETTING: Fifteen different services that offer treatment, counselling or assistance to drug users or HIV-positive patients in the State of São Paulo, Brazil. PARTICIPANTS: Two hundred and ninety-four current or ex-cocaine and crack cocaine users. MEASUREMENTS: A structured interview schedule was developed consisting of 246 questions covering socio-demographic details, drug history, cocaine transitions and HIV-risk behaviours.
FINDINGS: Eighty-seven per cent of patients began using cocaine by snorting and 74% subsequently underwent a transition of route--68% towards smoking and 20% to injecting. Half of all transitions occurred in the first 3 years following initiation into cocaine use. Factors associated with transitions were: younger age at cocaine initiation, more frequent use at peak usage, initial use of cocaine by snorting or injecting, a lower level of scholastic attainment and experience with a wider range of drug classes. A cohort effect was apparent with younger cocaine users and those who had begun using after 1990 being more likely to undergo a transition to smoking crack and less likely to start injecting.
CONCLUSIONS: Cocaine transitions are very common and are usually towards routes associated with a higher dependency potential and increased HIV-risk behaviour. Further research is needed to see if transitions can be prevented by early identification of potential cases.