Pediatric anxiety disorders can have a chronic course and are considered gateway disorders to adult psychopathology, but no consistent predictors of long-term outcome have been identified. A single latent symptom dimension that reflects features shared by all mental health disorders, the p factor, is thought to reflect mechanisms that cut across mental disorders. Whether p predicts outcome in youth with psychiatric disorders has not been examined. We tested whether the p factor predicted long-term psychiatric and functional outcomes in a large, naturalistically followed-up cohort of anxiety-disordered youth.

Children and adolescents enrolled in a randomized controlled treatment trial of pediatric anxiety were followed-up on average 6 years posttreatment and then annually for 4 years. Structural equation modeling was used to estimate p at baseline. Both p and previously established predictors were modeled as predictors of long-term outcome.

Higher levels of p at baseline were related to more mental health disorders, poorer functioning, and greater impairment across all measures at all follow-up time points. p Predicted outcome above and beyond previously identified predictors, including diagnostic comorbidity at baseline. Post hoc analyses showed that p predicted long-term anxiety outcome, but not acute treatment outcome, suggesting that p may be uniquely associated with long-term outcome.

Children and adolescents with anxiety disorders who present with a liability toward broad mental health problems may be at a higher risk for poor long-term outcome across mental health and functional domains. Efforts to assess and to address this broad liability may enhance long-term outcome.