The Netherlands Drug Situation 2010 - Trimbos-instituut

4 Problem drug use4.1 Prevalence estimates of problem drug users4.1.1 Problem hard drug users (opiates and cocaine): national estimatesThe previous national estimate of the number of problem hard drug users in the Netherlandspertained to the year 2001. This estimate has now been updated for the year 2008by means of the treatment multiplier (ST7_2010_NL_03) (Cruts et al. 2010). In order toapply (and improve) the treatment multiplier (TM), it was necessary to establish newestimates of the in-treatment rates. Methodologically, the in-treatment rate was definedas the proportion of drug users recorded in the National Alcohol and Drugs InformationSystem (LADIS) during the past year. This has been accomplished by field work in eightregions in the Netherlands (Amsterdam, Rotterdam, The Hague, Utrecht, Groningen, Enschede,Eindhoven, and Heerlen) by means of a standardized questionnaire for field research.Following an Amsterdam study, a distinction was made between problem hard drug(mainly opiate) users and “hard drug users" in methadone treatment, who function fairlywell, do not use heroin or other hard drugs, and are in this sense not problematic anymore(Buster et al. 2001). According to key informants, it was estimated that about 60per cent of the opiate users in treatment were problem drug users, being a total of about9,740 clients, apart from the 6,500 less problematic opiate users in treatment. The problemhard drug users were defined as the socially marginalized drug users who, during thepast month, used opiates, crack cocaine or amphetamines at least three days a week,and who showed criminal activities, had a psychiatric disorder, had a lifestyle causingpublic nuisance, or had an instable housing situation.A total of 572 hard drug users were recruited (on the street and at various locationsknown to attract drug users), and in-treatment rates were calculated separately foropiate users and crack cocaine users who do not use opiates. For the opiate users an intreatmentrate was found of 87 per cent, and for the crack cocaine users a much lowerin-treatment rate was found of only 41 per cent. It was concluded that a reliable estimatecould only be made about the number of problem opiate users and not yet aboutthe number of crack cocaine users.For the problem opiate users, an in-treatment rate of 87 per cent implies a multiplier of1.15. Applying this multiplier to the 9,740 socially marginalized problem opiate users whoare in treatment, their total number is estimated at about 11,200. Adding the 6,500 lessproblematic opiate users who are in treatment, all in all leads to an estimated number of17,700 more or less problematic opiate users in the Netherlands in 2008. The 95%-confidence interval runs from 17,300 up to 18,100 opiate users.Table 4.1.1 lists the national estimates of the number of problem hard drug users basedon surveys conducted several times in the past years. Due to the large confidence intervals,the estimate for 2001 did not differ significantly from the previous estimate for theyear 1999. Compared to the previous years 1993 up to including 2001, however, thenumber of more and less problem opiate users has clearly decreased in 2008. For 2008,the number of problem opiate users per 1,000 inhabitants aged 15 through 64 years isnow estimated at only 1.60 (range: 1.56-1.64), compared to 2.7 in 1999. The decrease53