Large decline in injecting drug use in Amsterdam, 1986-1998: explanatory mechanisms and determinants of injecting transitions.
OBJECTIVE
To study community wide trends in injecting prevalence and trends in injecting transitions, and determinants.


METHODS
Open cohort study with follow up every four months (Amsterdam Cohort Study). Generalised estimating equations were used for statistical analysis.


METHODS
Amsterdam has adopted a harm reduction approach as drug policy.


METHODS
996 drug users who were recruited from 1986 to 1998, mainly at methadone programmes, who paid 13620 cohort visits.


RESULTS
The prevalence of injecting decreased exponentially (66% to 36% in four to six monthly periods). Selective mortality and migration could maximally explain 33% of this decline. Instead, injecting initiation linearly decreased (4.1% to 0.7% per visit), cessation exponentially increased (10.0% to 17.1%), and relapse linearly decreased (21.3% to 11.8%). Non-injecting cocaine use (mainly pre-cooked, comparable to crack) and heroin use strongly increased. Trends were not attributable to changes in the study sample.


CONCLUSIONS
Harm reduction, including large scale needle exchange programmes, does not lead to an increase in injecting drug use. The injecting decline seems mainly attributable to ecological factors (for example, drug culture and market). Prevention of injecting is possible and peer-based interventions may be effective. The consequences of the recent upsurge in crack use requires further study.
van Ameijden
E J
EJ
Trimbos Institute (Netherlands Institute of Mental Health and Addiction), Utrecht, The Netherlands. eameijden@trimbos.nl
Coutinho
R A
RA
D000328:Adult; D015331:Cohort Studies; D003627:Data Interpretation, Statistical; D005260:Female; D003932:Heroin / Q000008:administration & dosage*; D006801:Humans; D015994:Incidence; D008297:Male; D009294:Narcotics / Q000008:administration & dosage*; D018671:Needle-Exchange Programs; D009426:Netherlands / Q000453:epidemiology; D015995:Prevalence; D015819:Substance Abuse, Intravenous / Q000453:epidemiology* / Q000517:prevention & control
D009294:Narcotics; D003932:Heroin