mortality ratios (Rehm, et al., 2005); more psychological problems (Chatham, et al., 1999; Mills, Teesson, Darke, Ross, & Lynskey, 2004); and were more likely to sustain abstinence after treatment (Darke, et al., 2007a) than men. The evidence regarding sex differences in polysubstance use and dependence amongst heroin users is mixed, with one study finding no differences in the number of current or lifetime diagnoses (Darke & Ross, 1997), another found higher levels of polydrug use amongst male heroin users (Darke & Hall, 1995) and another finding no sex differences in class memberships based on polysubstance use (Monga, et al., 2007).
