“…The EMCDDA had utilized: (i) national estimates of problem opioid users or IDUs, which are typically derived by CRC methods (Fienberg, 1972; Frischer et al., 1993; King & Brooks, 2001) and below ; (ii) national statistics on drug-induced deaths, some subject to substantial registration delays (see http://www.rss.org.uk/site/cms/newsarticle.asp?chapter=15&nid=33; accessed on 12 April 2012), others to under-reporting (Janssen, 2011); and (iii) studies of mortality among problem drug users who, for the most part, were enlisted because they had attended drug treatment services, been arrested, or been diagnosed with a blood-borne virus (see, e.g. Strang, McCambridge, & Best, 2003; Davoli, Bargali, & Perucci, 2007; Hickman et al., 2009; McDonald et al., 2009; Bird on behalf of European COSMO Workshop, 2010; Kimber et al., 2010; Gibson, Randall, & Degenhardt, 2011; Merrall, Bird, & Hutchinson, 2012).…”