A decline in the prevalence of injecting drug users in Estonia, 2005-2009

Aims: Here we report a study aimed at estimating trends in the prevalence of injection drug use between 2005 and 2009 in Estonia. Background: Descriptions of behavioural epidemics have received little attention compared with infectious disease epidemics in Eastern Europe. Methods: The number of injection drug users (IDUs) aged 15-44 each year between 2005 and 2009 was estimated using capture-recapture methodology based on 4 data sources (2 treatment data bases: drug use and non-fatal overdose treatment; criminal justice (drug related offences) and mortality (injection drug use related deaths) data). Poisson log-linear regression models were applied to the matched data, with interactions between data sources fi{ligature}tted to replicate the dependencies between the data sources. Linear regression was used to estimate average change over time. Results: There were 24305, 12,292, 238, 545 records and 8100, 1655, 155, 545 individual IDUs identifi{ligature}ed in the four capture sources (police, drug treatment, overdose, and death registry, accordingly) over the period 2005-2009. The estimated prevalence of IDUs among the population aged 15-44 declined from 2.7% (1.8-7.9%) in 2005 to 2.0% (1.4-5.0%) in 2008, and 0.9% (0.7-1.7%) in 2009. Regression analysis indicated an average reduction of about 1600 injectors per year. Conclusion: While the capture-recapture method has known limitations, the results are consistent with other data from Estonia. Identifying the drivers of change in the prevalence of injection drug use warrants further research.