Screening Performance of the <scp>DSM</scp> ‐5 Level 1 Cross‐Cutting Symptom Measure to Detect Psychiatric Comorbidity Among Youth: A Community‐Based Study

INTRODUCTION: Detection of psychiatric comorbidity is essential given its high burden and frequent under-recognition. The DSM-5 Level 1 Cross-Cutting Symptom Measure (DSM-XC) is a multidimensional screener designed to capture relevant psychopathological domains, yet its ability to detect comorbid conditions remains unclear. In this study, we evaluated the DSM-XC's capacity to screen additional psychiatric comorbidity in individuals with an existing psychiatric diagnosis. METHODS: Cross-sectional data from 796 individuals aged 22 years (60.8% female) from the 1993 Pelotas birth cohort in Brazil were analysed. Participants were included if they met criteria for at least one of seven psychiatric diagnoses based on structured clinical interviews. Screening accuracy metrics were calculated for targeted DSM-XC domains in identifying secondary diagnoses (e.g., depression domain for major depressive disorder [MDD]), using standard and Youden-optimized thresholds. Non-targeted performance assessments (e.g., anxiety domain for MDD) were also performed. Additionally, all 13 domains and the total score were evaluated for detecting any comorbidity. RESULTS: For the targeted domain assessment, high sensitivity and negative predictive values were observed using original thresholds, supporting rule-out utility, but specificity and positive likelihood ratios were low. The application of optimized thresholds increased specificity, with positive likelihood ratios reaching ~2 across domains. Non-targeted domains frequently outperformed targeted domains. Good discrimination for detecting any comorbidity was achieved using the DSM-XC total score (AUC = 0.75), with a cutoff of ≥ 21 providing the best balance between sensitivity (0.71) and specificity (0.69) and acceptable likelihood ratios. CONCLUSIONS: DSM-XC domains are useful for excluding comorbidities but have limited confirmatory value. The total score provides a global indicator of comorbidity. These findings support the DSM-XC primarily as a rule-out transdiagnostic triage tool for improving comorbidity detection in community settings.