2. Characteristics of incident substance-induced psychosis compared to incident first episode psychosis. A nationwide register-linkage study

Aim is to describe sociodemographic and work-related factors and psychiatric disorders among persons with substance-induced psychosis (SIP) prior to the incident psychotic episode, in comparison to persons with other types of first-episode psychosis (FEP).

Incident SIP cases at age 16-65 years (n=7320, 79.4% male) were identified from the Swedish National Patient Register during the years 2006-2016, and matched 1:1 (age, gender, and calendar year) with incident FEP cases. Information from sociodemographic background, psychiatric disorders, and work-related factors during the proceeding two-year period before the incident SIP/FEP episode were linked from national registries. Comparisons between SIPs vs FEPs were done using logistic regression analysis, adjusted with education level, family situation, type of living area, country of origin and Charlson Comorbidity Index. Conflict of interest: none.

Previous self-harm (23% vs 11.3%; OR 2.1, 95%CI 1.9-2.3), ADHD (14.4% vs 9%; OR 1.4, 95%CI 1.3- 1.6) and substance dependence (21.8% vs 4.6%; OR 4.9, 95%CI 4.3-5.7) were more prevalent among SIPs compared to FEPs. In turn, all other previous psychiatric disorder diagnoses were less prevalent among SIPs. Compared to FEPs, SIPs were more often unemployed (31.5% vs 24.6%; OR 1.2, 95%CI 1.1-1.4) and had less likely any employment (29.3% vs 31.1%; OR 0.9, 95%CI 0.8-0.96), but also, they were less often on a sickness absence over 90 days (8.6% vs 10%; OR 0.8, 95%CI 0.7- 0.95).

Assessment of suicidality and ADHD treatment should be carried out for persons with substanceinduced psychosis. Support for employment and needs for social security among persons with SIP are warranted.