Psychiatric Comorbidity Among Patients on Methadone Maintenance Therapy and Its Influence on Quality of Life

Background and Objectives: Co-occurring psychiatric disorders are among the difficulties faced by patients with opioid dependence on methadone maintenance therapy (MMT). This study aims to assess the prevalence of psychiatric comorbidity among patients on MMT, the factors predicting psychiatric comorbidity and to examine the association between psychiatric comorbidity and quality of life. Methods: A total of 225 male patients on MMT in a tertiary hospital in Malaysia were assessed for psychiatric comorbidity and substance use disorders using the Mini-International Neuropsychiatric Interview (MINI) and Opiate Treatment Index (OTI). Their quality of life was assessed using World Health Organization Quality of Life (WHOQOL)-BREF. Results: The prevalence of a current and lifetime non-substance use Axis I psychiatric disorder was 14.2% and 15.6%, respectively, while 14.7% fulfilled the criteria for antisocial personality disorder. 80.9% had comorbid substance dependence, predominantly nicotine dependence. Factors significantly associated with a non-substance use Axis I psychiatric disorder on multivariate analysis were use of psychiatric medications, antisocial personality disorder and poorer physical health. Patients with a non-substance use Axis I psychiatric disorder had a significantly poorer quality of life in all domains namely physical health, psychological, social relationships, environment as well as combined quality of life and general health after controlling for possible confounders. Conclusion: Psychiatric comorbidity among patients on MMT negatively impacts quality of life. Scientific Significance: The detection of psychiatric disorders and provision of appropriate treatment is needed to improve the quality of life of patients on MMT.