Table 2.

Cannabis-Related Outcome Measures Used in Clinical Trials of Comorbid Psychosis and Cannabis Use Disorder

Study	Population	Intervention	Self-report measures of cannabis exposure	Scales	Biochemical measures
CapOpus48	Psychosis and cannabis use disorder, age 18–35, and managed by an early intervention team (n=103)	Motivational interviewing and cognitive behavioral therapy vs. treatment as usual	Number of days cannabis use in the past month, assessed using TLFB “Standard” joints per month. Defined as 0.17 g high-potency cannabis or 0.5 g of cannabis resin, assessed using TLFB	None	Plasma THC, THC-OH, and THC-COOH concentration
Rabin et al.49	Schizophrenia or schizoaffective disorder and cannabis dependence (n=19)	Single-arm trial of contingency management and individual supportive therapy	Cannabis in grams/day over 4 weeks, assessed using TLFB	Marijuana Withdrawal Checklist	Qualitative urinalysis Creatinine-normalized urine THC-COOH concentration
CIRCLE50	Psychosis and cannabis use disorder, age 18–36, and managed by an early intervention team (n=551)	Contingency management (up to £240)+psychoeducation vs. psychoeducation alone	Number of days cannabis use in the past 3 months, assessed using TLFB	None	Qualitative urinalysis
Smeerdijk et al.51	Recent-onset schizophrenia (n=75) and their parents	Family motivational intervention vs. routine family support	Number of days cannabis use in the past 3 months, assessed using TLFB Cannabis in grams/day assessed using TLFB	Obsessive Compulsive Drug Use Scale	Qualitative urinalysis
Schnell et al.52	Schizophrenia or schizoaffective disorder and cannabis abuse or dependence (n=30)	Clozapine vs. ziprasidone	Joints per month, assessed using a detailed interview	Stages of Change Readiness and Treatment Eagerness Scale	Qualitative urinalysis and toxicological hair analysis

THC, delta-9-tetrahydrocannabinol; THC-COOH, 11-nor-9-carboxy-THC; THC-OH, 11-hydroxy-THC; TLFB, Timeline Followback.