Abstract
OBJECTIVES: Fried () quantified the overlap of items among seven widely used depression rating scales. The analysis revealed substantial heterogeneity of the depressive syndromes and a low overlap among the scales. To our best knowledge, there are no studies evaluating the content overlap of (hypo)mania scales. The goal of our study, therefore, is to quantify the overlap of items among seven widely used (hypo)manic scales, implementing the methodology developed by Fried (). METHODS: Seven commonly used (hypo)manic scales underwent content analysis. Symptom overlap was evaluated with the use of the Jaccard index (0 = no overlap, 1 = full overlap). In case of every scale, rates of idiosyncratic symptoms and rates of specific versus compound symptoms were calculated. RESULTS: The seven scales gathered 64 hypo(manic) symptoms. The mean overlap among all of the instruments was low (0.35), the mean overlap of each scale with all others ranged from 0.29 to 0.48, and the overlap among individual scales ranged from 0.20 to 0.65. Thirty-six percent of symptoms appeared only on one scale. Only 6% of the symptoms appeared on all of the instruments. CONCLUSIONS: We have shown that using (hypo)manic scales as interchangeable measurements may be problematic.