The ICD-10 was used to diagnose current SUDs, the current type and severity of psychiatric problems, and the level of functioning . All patients were interviewed with a clinical psychiatric examination, supported by the Mini International Neuropsychiatric Interview (MINI) version 2005. The MINI is a short psychiatric interview for the assessment of psychiatric disorders, which is in accordance with the Diagnostic and Statistical Manual of Mental Disorders, Fourth Edition and ICD-10 classification systems . This interview has high acceptance and validity [17, 18]. Interviews were conducted by senior psychiatrists and psychologists with several years of clinical and research experience in the psychiatric assessment of patients with physical disorders. Severe SUD was indicated by the injection of illicit drugs within 6 months before admission and a high lifetime frequency of overdoses.