A small area analysis estimating the prevalence of addiction to opioids inBarcelona, 1993

Study objective-To determine the distribution of opioid use prevalence in s mall areas and its relation with socioeconomic indicators. Design-Capture-recapture was applied using data from the Barcelona Drug Inf ormation System for 1993 (treatment demands, hospital emergency room visits , deaths from heroin acute adverse reaction and pre-trial prison admissions ). To avoid dependence between sources, a log-linear regression model with interactions was fitted. For small neighbourhoods, where capture-recapture estimates were not obtainable, the Heroin Problem Index (HPI) was used to p redict prevalence rates from a regression model. The correlation between es timated opioid use prevalence by neighbourhoods and their socioeconomic lev el was computed. Main results-The city's estimated prevalence was 12.9 opioid addicts per 10 00 inhabitants aged 15 to 44 years (95% CI:10.1, 17.2), which represents 91 76 persons. The highest rate was found in the inner city neighbourhood. Com paring rates obtained for each neighbourhood with their unemployment rates, a high correlation coefficient was obtained (r = 0.80, p < 0.001). Conclusion-The main contribution of this study is that of combining capture -recapture with the HPI to produce small area prevalence estimates, which w ould not have been possible using only one method. Areas with higher socioe conomic status showed proportionally low addiction prevalences, but in depr essed areas, prevalences varied widely.