Frisher and Forsyth1 question whether the number of problematic drug users (PDUs) has increased or decreased in the 21st century, what the impact of treatment has been, particularly with reference to drugs-related deaths, and the Drug Harm Index’s reliance on readily available published data. These and other questions, particularly about injector incidence, off-injecting rates and model, as well as statistical, uncertainty, are addressed in 21^st Century Drugs and Statistical Science in the UK, which was published in December 2008 by the Home Office’s Surveys, Design and Statistics Subcommittee (chair: S.M.B.) and is available at http://www.homeoffice.gov.uk/documents/science-advisory-committee/ (accessed 16 January 2008).

The report includes an …