Item Content and Overlap Analysis of common Depression and Anxiety Scales

Background: Although overlap between depression and anxiety scales has been investigated separately, research examining shared and unique symptom profiles across both domains is limited. Given that comorbidity between depressive and anxiety disorders can reach up to 65%, understanding symptom-level overlap could provide valuable insights for improving diagnostic accuracy and developing targeted transdiagnostic assessments. Methods: We conducted a content analysis of 18 widely used clinical scales, assessing both depression and anxiety domains individually and together. Using the Jaccard Index (0 = no overlap; 1 = complete overlap), we quantified overlap across individual depression scales, individual anxiety scales, and combined depression and anxiety scales to capture symptom-level intersections. Results: Our findings indicated low mean overlap within each domain (0.29 and 0.26 for depression and anxiety, respectively) and even lower mean overlap (0.13) when depression and anxiety scales were analyzed together, underscoring significant heterogeneity among scales. The Hamilton Rating Scale for Depression (HRDS) and Hamilton Anxiety Rating Scale (HAM-A) displayed the highest cross-domain overlap (0.41), suggesting these scales may assess overlapping symptom dimensions. Conclusion: Results reveal distinct symptom structures in depression and anxiety scales, with only a limited degree of shared content. This suggests that many current scales may inadequately capture the mixed symptoms often present in clinical populations. Our findings underscore the importance of developing transdiagnostic measures capable of assessing both shared and distinct symptom dimensions across affective disorders, which may ultimately enhance clinical precision in assessing comorbid presentations and inform future revisions of existing assessment tools