Psychiatric Comorbidity Reduces Quality of Life in Chronic Methadone Maintained Patients

Despite the efficacy of methadone maintenance treatment (MMT), opioid dependence still involves severe impairment of functioning and low quality of life. This study examines the influence of the psychiatric comorbidity of MMT patients on their quality of life. A total of 193 middle-aged patients in long-term MMT were assessed for current and lifetime Axis I psychiatric disorders, substance use disorders, and personality disorders using the MINI, the CIDI-SAM, and the SIDP-IV. Quality of life (Qol) was assessed using the EQ-5D. Psychiatric comorbidity was documented in 78% of the patients. Mood disorders (60%) and anxiety disorders (46%) were the most common diagnoses. Additional substance use disorders were diagnosed in 70% of the MMT patients. While a probable personality disorder was documented for 65% of the patients, 66 of these patients actually showed an antisocial personality disorder. Qol was severely diminished to a level comparable to that for patients with chronic psychiatric and/or somatic disorders. Multivariate analyses showed the occurrence of comorbid psychiatric disorders to explain about 32% of the variance in Qol. The quality of life for MMT patients is generally low. The present results showed a high rate of psychiatric comorbidity for this patient group with mood disorders, additional substance use disorders, and personality disorders occurring in particular. Such comorbid psychopathology substantially affects quality of life. The negative influence of comorbid psychopathology on quality of life is an important reason to provide additional mental health services for MMT patients. (Am J Addict 2009; 18: 470-480)