The most influential decision factors for choosing a formal diagnostic classification system for describing personality pathology.

There are currently three models for diagnosing personality disorders for practitioners to choose from in the formal diagnostic classification systems Diagnostic and Statistical Manual of Mental Disorders (DSM) and International Classification of Diseases (ICD): the categorical model retained from DSM-IV, a dimensional model in the ICD-11, and the DSM-5 Alternative Model for Personality Disorders (AMPD) that is a hybrid of categorical and dimensional methods. We used a sequential mixed-methods approach to explore how psychologists and psychiatrists decide which model to use for diagnosing personality pathology. In Study 1, we elicited eight themes and seven subthemes that capture the factors that psychologists and psychiatrists (N = 18) consider when deciding whether or not to use the AMPD. In Study 2, these themes were converted to 16 statements reflecting factors that practitioners might consider when deciding which diagnostic model to use when working in a therapeutic role. Psychiatrists (n = 13) and psychologists (n = 70) rated each of the 16 factors according to the degree to which they influence deciding which diagnostic model to use. The most important factors were those pertaining to usefulness in communicating personality information, knowledge about and training in each model, usefulness of the model for describing clients' difficulties and pathology, and level of acceptance of the model by peers and experts in the field. While our data do not identify which model lends itself best to clear communication about personality functioning, or which model is most scientifically sound and accepted within the field, our data indicate that practitioners consider those things important, so clear guidance about those matters based on empirical evidence is needed. (PsycInfo Database Record (c) 2026 APA, all rights reserved).