Patterns of Substance Use Disorders and Associated Co-occurring Psychiatric Morbidity among Patients Seen at the Psychiatric Unit of a Tertiary Health Center.

Background: Understanding the pattern of co-occurring mental illness in patients with substance use disorders (SUDs) is essential in improving the prevention and treatment of substance use-related problems. This study examined the pattern of SUDs, the associated co-occurring psychiatric morbidities, and associated factors among patients with SUDs managed at a tertiary health center. Methods: The records of patients who presented with SUDs between 2010 and 2019 were examined. Socio-demographics of interest were extracted from case files. Substance use diagnoses, as well as associated co-occurring mental illness, were extracted and entered into SPSS software. Bivariate analyses including the risk of developing co-occurring mental disorder were calculated. Findings: For most patients, the initiation of substance use was before the age of 21 years, while the onset of SUDs was between 21-30 years. Cannabis use disorders (CUDs), alcohol use disorders (AUDs), and nicotine use disorders (NUDs) were the commonest SUDs. Compared with those with CUDs, non-users of cannabis were significantly less likely to develop co-occurring mental illness [odds ratio (OR) = 0.25, 95% confidence interval (CI) =0.13-0.42, P = 0.001]. Those with tramadol use disorders (OR = 2.13, 95% CI = 1.03-4.41, P = 0.040) and those without pentazocine use disorders (P = 0.003) were more likely to have a comorbid mental illness. Patients with AUDs (P = 0.001), CUDs (P = 0.001), NUDs (P = 0.001), and tramadol use disorders (P = 0.045) were significantly more likely to be multiple substance users. Conclusion: Results suggest an association between SUDs and co-occurring mental illness, though differences in these associations were noticed across the categories of substances. This emphasizes a holistic approach to prevention and care of patients presenting with SUDs.