Estimating injection drug use prevalence using state wide administrative data sources: Estonia, 2004

Estonia has rapidly expanding injection drug use (IDU) driven HIV/AIDS epidemic with the highest reported incidence rate and prevalence (1.3%) of HIV in the European region. To evaluate the feasibility of IDU prevalence estimations based on routine nationwide data sources using capture-recapture methodology, and provide estimates of IDU prevalence. IDUs were identified from the Police, Health insurance fund, State HIV reference laboratory data sources. Poisson regression models were fitted to the observed data, with interactions between data sources fitted to replicate 'dependencies' between the data sources. There were 13,886 (95% CI 8132-34,443) IDUs in Estonia in 2004, which translates into a prevalence of 2.4% (95% CI 1.4-5.9%) among people aged 15-44 years. The estimate is in line with the estimate provided by the panel of experts and estimates from the neighbouring countries experiencing similar societal and economic challenges.