5. Antipsychotic use and associating factors among persons with substance-induced psychosis and first-episode psychosis. A nationwide register-linkage study

Aim of the study was to investigate the antipsychotic use and associated factors in persons with substance-induced psychosis (SIP) and compared with persons with other first-episode psychosis (FEP).

Incident Swedish SIP cases (n=7320) during 2006-2016 were identified from health care registers, matched 1:1 with persons with FEP (n=7320) by age, gender and calendar year of diagnosis. Prevalence of antipsychotic use was assessed as point prevalence every six months, from 3 years before until 3 years after the first diagnosis. Factors associating with antipsychotic use among SIP was analysed with multivariable logistic regression including information on sociodemographic and work-related background, including disability pension and sickness absence, SIP types, and psychiatric diagnoses. Conflict of interest: none.

Among SIP and FEP, the prevalence of antipsychotic use was low before the first diagnosis (3-7% in SIP, 8-16% in FEP), peaked 6 months after the first diagnosis (23% in SIP, 54% in FEP) and stabilized after that. After 3 years of first-diagnosis, 19% of persons with SIP and 45% of persons with FEP used antipsychotics. Antipsychotic use one year after diagnosis among SIP was associated with previous substance use disorder, depression, anxiety and personality disorder diagnoses, being on disability pension or on long-term sickness absence (>90 days), and cannabis- or multisubstanceinduced psychosis.

Although substance-induced psychoses are considered to be short-lived, antipsychotic use after incident SIP episode is relatively common, especially among those with cannabis- or multisubstance-induced psychoses. Previous psychiatric comorbidity and poorer ability to work seem to increase the odds for antipsychotic medication use.