Differences in the Prevalence of Use and Dosage of Psychotropic Drugs by Smoking Status in Inpatient and Outpatient: An Observational, Analytical, Cross-Sectional Study

Objective: To estimate the association between tobacco use and the prevalence of psychotropic medication use and prescribed dosage among inpatients and outpatients with severe mental disorders treated at a neuropsychiatric hospital.

Methods: Observational, cross-sectional, analytical study conducted on May 3, 2023. Smoking status and prescribed psychotropic medications were recorded for all hospitalized patients and community-based outpatients. Dosages were reported in mg/day, defined daily doses (DDD), and for antipsychotics as chlorpromazine equivalents (CPZeq). Bivariate and multivariate analyses were performed.

Results: Tobacco use data were collected from 325 out of 425 total patients (71.7% male, mean age [SD]: 51.4 [14.4] years, 56% inpatients, 70.2% with schizophrenia and related psychosis). The prevalence of smoking was 72.3%, with differences by gender (78.1% in males vs. 57.8% in females, p < 0.001), and decreased with age (18–39 years: 86.1%; 40–59 years: 71.7%; ⩾ 60 years: 63.2%; p = 0.01). Mean dosages of antipsychotics, clozapine, and olanzapine measured in CPZeq were higher in smokers than in non-smokers by 35.4%, 37.1%, and 33.3%, respectively. After adjusting for confounding factors, smoking was associated with a 21.8% higher dosage of antipsychotics (95% CI: 0.4%–43.2%; p = 0.046), equivalent to an additional 132.2 mg/day (24.2–240.1; p = 0.017) of clozapine and 5.4 mg/day (1.2–9.6; p = 0.012) of olanzapine. The average dosage of sedatives/hypnotics was 45.5% higher among smokers (13.6%–89.5%; p = 0.008).

Conclusion: A high prevalence of smoking was found among patients with severe mental disorders, associated with higher average dosages of sedatives/ hypnotics and antipsychotics, particularly clozapine and olanzapine. Psychopharmacology Bulletin. 2026;56(1):48–63.