Naloxone challenge as a biological predictor of treatment outcome in opiate addicts.

Thirty seven consecutive applicants to methadone maintenance were assessed for depression and for level of opiate dependence using a 0.8-mg naloxone challenge. Nineteen of the applicants met DSM-III-R criteria for current major depression. At 3-month follow-up, high naloxone challenge test (NCT) scores at intake (high levels of opiate addiction) were found to predict poor program retention and elevated symptoms of depression at follow-up. Reports of heavy current drug use at intake were also associated with poor program retention and with high frequencies of positive urine screens for illicit substances during treatment. Level of addiction and reported amount of drug use at intake independently predicted program retention with a multiple correlation of 0.46 (P less than .01). Although NCT predicted depression at follow-up, depression at intake did not significantly predict treatment outcome, and NCT score predicted outcome independently of psychopathology.