Co-occurring medical and substance use disorders in patients with schizophrenia: a systematic review

Comorbid medical and substance use disorders are common in people with schizophrenia. The aim of this systematic review was to summarize evidences on co-occurring medical and substance use disorders (SUDs) in patients with schizophrenia. A Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) review was conducted. Medline, CinAHL, Embase, PsycINFO, and the Cochrane Library were searched to August 31, 2016 without restriction by publication status. Publications were screened according to predefined inclusion criteria. Qualitative analysis was undertaken for this systematic review. Twenty-six materials published from 1990 to 2015 were included in a qualitative analysis. From a total of 202 articles identified, 26 articles were eligible for systemic review. The evidence shows that 18.5 to 90% of people with schizophrenia develop any SUDs at some point in their lives including nicotine and 18.5% to 61.5% excluding nicotine. Nicotine use disorders are particularly common in people with schizophrenia, with a lifetime prevalence of roughly 58-90% followed by alcohol, khat, and cannabis use disorders, respectively. In addition, up to 80% of people with schizophrenia have recognizable medical disorders of which approximately up to 50% remain undetected and medical problems may explain or exacerbate their condition in about 20% of people with schizophrenia. This systematic review indicates that comorbid medical disorders and SUD are common in people with schizophrenia. Routine screening and integrated management of medical and substance use disorders is implicated in persons with schizophrenia.