IMPORTANCE: Transition to adult care is a challenging and complex process for youth and emerging adults with chronic health and/or mental health conditions. Patient navigation has been proposed to improve care during transition, but previous studies have used single disease cohorts with a nonrandomized design. OBJECTIVE: To compare the effectiveness of a patient navigator service to reduce emergency department (ED) use among adolescents and emerging adults with chronic health and/or mental health conditions undergoing transition to adult-oriented health care. DESIGN, SETTING, AND PARTICIPANTS: This was a pragmatic, parallel-group, nonblinded randomized clinical trial design. Patients were followed up for a minimum 12 months and maximum 24 months after enrollment. The setting was the Canadian province of Alberta, with a population of 4.3 million inhabitants, having 3 tertiary care pediatric hospitals serving the entire population with universal health coverage. Participants included youth aged 16 to 21 years, followed up within a diverse array of chronic care clinics, expected to be transferred to adult care within 12 months, residing in Alberta, Canada. INTERVENTIONS: A 1:1 allocation to either access to a personalized navigator, an experienced social worker within the health services environment, or usual care, for up to 24 months after randomization. MAIN OUTCOMES AND MEASURES: All-cause ED visit rate while under observation. RESULTS: A total of 335 participants were randomized over a period of 45 months, 164 (49.0%) to the intervention arm and 171 (51.0%) to usual care. After 1 patient withdrew, 334 participants (usual care: mean [SD] age, 17.8 [0.7] years
99 female [57.9%]
intervention: mean [SD] age, 17.7 [0.6] years
81 male [49.7%]) were included in the final data analysis. Among the participants, 131 (39.2%) resided in a rural location, and 126 (37.7%) had a self-reported mental health comorbidity during baseline assessment. We observed significant effect modification in the relationship between intervention and ED visits based on mental health comorbidity. Among those with a self-reported mental health condition, ED visit rates were lower in those with access to the navigator, but the association was not significant (adjusted incidence rate ratio [IRR] 0.75
95% CI, 0.47-1.19). Among those with no mental health comorbidity, the corresponding adjusted IRR was 1.45 (95% CI, 0.95-2.20). CONCLUSIONS AND RELEVANCE: In this randomized clinical trial, the navigator intervention was not associated with a significant reduction in ED visits among youth with chronic health conditions transitioning to adult care. The study did not accrue sufficient sample size to demonstrate a significant difference between groups should it exist. TRIAL REGISTRATION: ClinicalTrials.gov Identifier: NCT03342495.