"The probable number of problem drug users in Greece continues to be estimated every year by the internationally recommended 'capture-recapture' method, based on the annual data from the
Treatment Demand Indicator. An appropriate statistical model is fitted to the records from three sources of information: KETHEA, 18 ANO and the rest of the network of treatment services reporting to the Focal Point. This permits the estimation of the 'hidden population' of people who are problem drug users but did not happen to be recorded by any of these sources in the year in question. Because of this method of estimation, the definition of a problem drug user is someone who may eventually attend the treatment services because of his or her use of opiates. The lack of data in the appropriate form from other sources that might record problem drug users, such as the Police, is regrettable as it prevents checking and possible improvement of our current estimates.
"The estimated total number of problem drug users aged 15-64 years with main substance heroin was 20,473 in the year 2011, with 95% confidence interval from 18 529 to 22 688. This is down from the previous year’s estimate of 22,515 (95% c.i. from 20,202 to 25,171), although as always it is necessary to take into account that the confidence intervals are very wide. However, the 2010 estimate was in turn down from the 2009 figure of 24,097 (95% c.i. 21,362 – 27,272) and thus it appears that the generally increasing trend which had been observed since 2002 may have come to an end. Table 4.1 gives the breakdown of the estimated number of problem drug users by gender, age and place of residence. Table 4.2 presents corresponding estimates of the number of drug users who reported that they had injected in the previous month. The estimated total of 7 847 (95% c.i. 6,904 – 9,951) is likewise reduced in comparison to the previous two years."


University Mental Health Research Institute, "2012 National Report (2011 Data) to the EMCDDA by the Reitox National Focal Point: Greece: New Development, Trends and in-depth information on selected issues" (Athens, Greece: UMHRI, 2012), p. 55.