World Drug Report 2006 - United Nations Office on Drugs and Crime

Methodology
country’s participation in the ESPAD school surveys, a regression analysis g with data from other countries in the
region suggested that a prevalence rate of around 0.9% could be expected. Based on the number of newly
registered HIV cases in this country in 2002, related to injecting drug use (and thus to injecting of opiates), a
linear regression analysis with opiate abuse in other countries of the region suggested that a prevalence rate of
1.2% of the population age 15-64 could be possible. However, it must be taken into account that the
correlation of opiate use and school survey results is not very strong and that the correlation between opiate
abuse and IDU-related HIV is very weak, as shown by available data from Eastern Europe and Western Europe.
The actual spread of the HIV virus among IDUs and differences in drug policies seem to account for this. It is
thus not possible to rely merely on school survey data or HIV data for extrapolation purposes. It is nonetheless
likely that the actual prevalence rate falls within the range of 0.2% to 1.2%. Given the lack of any clear
indication of the superiority of one method over another, the average of all three estimates was calculated
(0.8%) and used as UNODC’s estimate for the country. This estimate is about 4 times the number of
registered opiate users in the country. This is not uncommon, as similar ratios between total use and registered
use have also been found in a number of other countries.
Extrapolations based on treatment data
For a number of developing countries, the only drug related data available on the demand side was treatment
demand. In such cases, the approach taken was to look for other countries in the region with a similar socioeconomic
structure, which reported annual prevalence data and treatment data. As a next step, the ratio of
people treated per 1000 drug users was calculated for each country. The results from different countries were
then averaged and the resulting ratio was used to extrapolate the likely number of drug users from the number
of people in treatment.
Extrapolations based on school surveys
Analysis of countries which have conducted both school surveys and national household surveys shows that
there is, in general, a positive correlation between the two variables, particularly for cannabis, ATS and cocaine.
The correlation, however, is weaker than that of lifetime and annual prevalence or current use and annual
prevalence among the general population but stronger than the correlation between opiate use and IDU-related
HIV cases and, stronger than the link between treatment and drug use.
The following examples shows extrapolations of school survey results for cannabis for Western Europe. The
basis were the ESPAD School Survey results undertaken in 2003 and the annual prevalence estimates provided
by European member states to UNODC. As can be seen from the figure below, there is a positive correlation
between the two variables; the strength of this link, as indicated above, is however, less (R = 0.79) than the
strength of the link between life-time and annual prevalence.
g The linear regression was calculated by using the ‘forecast’ function in an Excel spreadsheet.
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