RESULTS	Two weeks of initial abstinence was moderately predictive of treatment success ( positive predictive value = 71 % ) , while opioid use in both of the first 2 weeks was strongly predictive of unsuccessful treatment outcome ( negative predictive value [ NPV ] = 84 % ) , especially when successful outcome was defined as total abstinence from opioids in weeks 9-12 ( NPV = 94 % ) .\