METHODS	Predictive values were calculated to determine the importance of abstinence versus use at various time points within the first month of treatment ( week 1 , weeks 1-2 , 1-3 , or 1-4 ) in predicting successful versus unsuccessful treatment outcome ( based on abstinence or near-abstinence from opioids ) in the last 4 weeks of buprenorphine-naloxone treatment ( weeks 9-12 ) .\