This report provides estimates of the prevalence of opiate and/or crack cocaine use at the regional and national level in England for 2011/12. It is a follow up to series of comparable prevalence estimates for 2004/05, 2005/06, 2006/07, 2007/08, 2008/09, 2009/10 and 2010/11. Estimates of the prevalence of opiate use, crack cocaine use and drug injecting (by users of opiates and/or crack cocaine) are also presented. Two prevalence estimation methods have been used; the capture-recapture method and the multiple indicator method. The capture-recapture method examines the overlap between different sources of data on individual drug users that are available at the local level to estimate the size of the hidden drug using population at the DAT area level. The multiple indicator method models the relationship between the capture-recapture estimates and readily available drug indicator data, such as numbers of drug offences in an area. It then applies that relationship to the areas where capture-recapture estimates are not available and provides estimates of drug use for those areas. The DAT area estimates are then summed to provide regional and national estimates.

In total there were an estimated 293,879 opiate and/or crack cocaine users aged 15 to 64 in England in 2011/12 (95% confidence interval (CI) 291,029 – 302,146). This converts to 8.40 per thousand population aged 15 to 64 (95% CI 8.32 – 8.63). The estimated prevalence of opiate use was 7.32 per thousand population aged 15 to 64 (95% CI 7.25 – 7.53) and the estimated prevalence of crack cocaine use was 4.76 per thousand (95% CI 4.62 – 4.96). The estimated prevalence of drug injecting was 2.49 per thousand population aged 15 to 64 (95% CI 2.44 – 2.58). Nationally, there was a fall in the prevalence of opiate and/or crack cocaine use between 2010/11 and 2011/12; however this was not statistically significant. There was also a slight non-statistical drop in the prevalence of opiate use from 261,792 in 2010/11 (95% CI 259,260 – 269,025) to 256,163 in 2011/12 (95% CI 253,751 – 263,501).

The estimates for the period 2011/12 also show a non-significant decrease in the levels of crack cocaine use from 170,627 in 2010/11 (95% CI 165,877 – 176,692) to 166,640 (95% CI 161,621 – 173,706). The injecting prevalence rates have significantly decreased between 2010/11 and 2011/12, going from 93,401 (95% CI 90,974 – 96,757) to 87,302 (95% CI 85,307 – 90,353).