Prevalence, Clinical Correlates and Explanatory Models of Substance Use among Patients with Schizophrenia: A Cross-sectional Study from a Tertiary Care Hospital, Southern India

Introduction: Prevalence rates of Substance Use Disorders (SUDs) in patients with schizophrenia are reported to be about twice of that of the general population. Co-morbid SUDs in these patients can affect the natural course of the illness, quality of life and treatment compliance. Increased rates of hospital admissions, longer duration of inpatient stay, more severe psychopathology, increased rates of criminal activity and violent behaviour have also been reported in this group of patients. Data from the region on substance use in patients with schizophrenia is sparse.

Aim: To study the prevalence of SUD’s in patients with schizophrenia and the risk factors associated with SUD’s and patient Explanatory Models (EM) regarding the same.

Materials and Methods: The present cross-sectional study was conducted in the Psychiatry Outpatient Clinic at Christian Medical College, Vellore, Tamil Nadu, India, from November 2016 to May 2017 in 103 consecutive patients with schizophrenia. Symptom severity was assessed using the Positive and Negative Symptom Scale (PANSS), substance use patterns with the Drug Abuse Screening Test (DAST), Alcohol Use Disorders Identification Test (AUDIT) and Fagerstrom’s Test for Nicotine Dependence (FTND) and patient EMs for substance use with a semi-structured questionnaire. Socio-demographic and clinical details were also recorded. Data was analysed using Statistical Package for Social Sciences (SPSS) software version 16.0.1. Chi-square test and the student’s t-test were used to assess the significance of association for categorical and continuous variables, respectively. The Pearson’s correlation coefficient was employed to assess the statistical significance of the association between two continuous variables. A p-value <0.05 was considered as statistically significant.

Results: The mean age of the participants was 37.54 years. The majority of the participants were males (n=60, 58.3%), 62 (60.2%) were married, 97 (94.2%) were literates and 54 (52.4%) participants were employed. The prevalence of substance use was seen in 30 (29.1%) participants. Nicotine was the most common substance of abuse (n=21, 20.4%) followed by alcohol (n=19, 18.4%). Male gender, being employed and a family history of substance use were factors significantly associated with any substance use with p-values 0.001, 0.001 and 0.01, respectively. Patient’s explanations for the use of the nicotine included the feeling of relaxation it produced (n=13, 61.9%), and feeling more energetic and active (n=12, 57.1%). Making one more relaxed and social (n=14, 73.7%) was the most common patient explanation for alcohol use.

Conclusion: Alcohol and nicotine were common substances of abuse among the participants in this study. It is useful to understand patient’s explanations for substance use in order to develop effective intervention programmes tailored to the individual patient’s beliefs.