The prognostic utility of personality traits versus past psychiatric diagnoses: Predicting future mental health and functioning.

Past psychiatric diagnoses are central to patient case formulation and prognosis. Recently, alternative classification models such as the Hierarchical Taxonomy of Psychopathology (HiTOP) proposed to assess traits to predict clinically-relevant outcomes. The current study directly compared personality traits and past diagnoses as predictors of future mental health and functioning in three independent, prospective samples. Regression analyses found that personality traits significantly predicted future first onsets of psychiatric disorders (ΔR2=06-.15), symptom chronicity (ΔR2=.03-.06), and functioning (ΔR2=.02-.07), beyond past and current psychiatric diagnoses. Conversely, past psychiatric diagnoses did not provide an incremental prediction of outcomes when personality traits and other concurrent predictors were already included in the model. Overall, personality traits predicted a variety of outcomes in diverse settings, beyond diagnoses. Past diagnoses were generally not informative about future outcomes when personality was considered. Together, these findings support the added value of personality traits assessment in case formulation, consistent with HiTOP model.