Hair analysis underestimates heroin use in prisoners

The value of hair analysis in measuring treatment outcome was examined in a randomised controlled trial (RCT) of an Australian state prison-based methadone programme between 1997 and 1998 (n = 382 male prisoners). Hair samples were analysed for morphine using immunoassay techniques. Agreement between hair analysis and self-report was tested using kappa, McNemar's test of symmetry and Pearson's correlation coefficient r. Hair analysis based on immunoassay was inadequate as the primary outcome measure for the RCT but had value in supplementing self-reported heroin use. There was a modest correlation (r = 0.31, p < 0.001) between self-reported frequency of heroin use and morphine concentrations in hair. Sectional hair analysis, a reflection of duration of drug use, was uninformative and generally impractical due to the length of hair sections needed.