Implementing Care for Cannabis and Other Drug Use in Adult Primary Care: Outcomes of a Cluster-Randomized Implementation Trial.

Abstract

The U.S. Preventive Services Task Force recommends substance use screening for adults when accurate diagnosis and follow-up treatment can be offered. This study evaluated whether implementation of population-based screening and symptom assessment increased treatment for cannabis and other drug use disorders in a large primary care system. Nineteen randomized regional healthcare system sites implemented population-based screening and symptom assessment for cannabis and other drug use as part of a stepped-wedge trial to integrate mental health in adult primary care from January 2016 to July 2018. Implementation strategies included practice facilitation, electronic health record decision support, and performance feedback. Outcomes included treatment initiation and engagement rates among patients with any new drug use disorder and, secondarily, the rates for specific drug use disorders (e.g., cannabis use disorder), using electronic health record and insurance claims data. Mixed-effect logistic regression modeled binary outcomes before and after implementation (January 2015-January 2019), adjusted for randomization stratification and time, accounting for person-level repeated outcomes. Monthly outcome rates (per 10,000 patient-visits) were estimated using marginal standardization. Analyses were conducted in 2023-2024. Before implementation, 244,542 patients had 942,400 visits; after implementation, 287,696 patients had 1,087,565 visits. Implementation resulted in an increased cannabis screening (9-153 per 10,000 patient-visits; p<0.001) and newly identified cannabis use disorder (10-17 per 10,000 patient-visits; p<0.001). Treatment initiation for cannabis use disorder increased by 0.5-1 per 10,000 patient-visits (p=0.006), but treatment engagement did not change (p=0.147). Treatment initiation and engagement for any drug use disorder did not change (p=0.777 and 0.584). Findings underscore the potential value of integrating population-based cannabis screening/assessment in primary care for treatment initiation and highlight the need for improved engagement for cannabis use disorder.