Leaving methadone maintenance treatment: the role of personality traits and psychiatric status.

This study investigates personality traits and psychiatric status among 174 methadone patients (121 men and 53 women) and 387 untreated controls (191 men and 196 women) in Sweden in 1993 and 1994. The methadone patients were followed up to 1998 with respect to being expelled from treatment. Pretreatment factors, like home background and behavioral factors, were studied in relation to treatment outcome. The methadone patients were interviewed using a structured questionnaire about alcohol and drug use and psychological, social, and behavioral factors. To obtain data about personality traits, the patients were asked to fill in a questionnaire, the Karolinska Scales of Personality (KSP) questionnaire. The male methadone patients had significantly (p < 0.0001) higher scores on somatic anxiety, muscular tension, impulsiveness, and psychasthenia, and significantly lower scores with regard to socialization, social desirability, and inhibited aggression compared with the controls. Compared with the female controls, the female methadone patients differed most significantly (p < 0.0001) in respect of socialization. Low socialization, social desirability, detachment, feelings of guilt, and suspicion were most predictive for later expulsion from treatment. Nearly half of the methadone patients who suffered from human immunodeficiency virus (HIV) infection had difficulties with compliance with the treatment and were later expelled. The results suggest that awareness of personality traits and psychiatric status may be crucial for a better methadone treatment outcome.