Diagnostic stability in substance-induced psychosis

Substance-induced psychosis (SIP) is the name given to a psychosis that starts in the context of substance abuse but persists for days and weeks with no substance use. There is as yet little knowledge about the longitudinal course of this psychosis, which suggests that significant numbers go on to be diagnosed with a severe mental disorder (SMD). The objective of this study was to analyse the progression of SIP to SMD in our environment and the possible factors that may be involved in that conversion.

We used a retrospective cohort follow-up design. We reviewed all diagnoses of patients discharged from the psychiatric hospitalisation unit of the University Hospital of Basurto from January 2002 to December 2015 inclusively. In addition to sociodemographic and clinical data, information was collected on the consumption of cannabinoids, opioids, amphetamines, cocaine and alcohol. The data were analysed using descriptive analysis, Kaplan-Meier survival curves and Cox regression.

Of the 116 patients, 78.4% were male, had an average age of 33.0 (SD = 8.9) years and 44.0% were single; 31.0% had a psychiatric family history; the most commonly used substance was cannabis (60.3%), followed by cocaine (40.5%). The cumulative risk of diagnostic conversion to an SMD in 16 years was 41.6% (95%CI: 32.2-52.2) over a mean 36.43 months.

In interventions in episodes of SIP we must bear in mind that a significant proportion will progress to an SMD in the first three years.