Bech, Per4; Csillag, Claudio3; Hellström, Lone3; Fleck, Marcelo Pio de Almeida3
1 Section of Neurology, Psychiatry and Sensory Sciences, Department of Clinical Medicine, Faculty of Health and Medical Sciences, Københavns Universitet2 Department of Clinical Medicine, Department of Clinical Medicine, Faculty of Health and Medical Sciences, Københavns Universitet3 unknown4 Department of Clinical Medicine, Department of Clinical Medicine, Faculty of Health and Medical Sciences, Københavns Universitet
Objective: To use principal component analysis (PCA) to test the hypothesis that the items of the Hamilton Depression Scale (HAM-D17) have been selected to reflect depression disability, whereas some of the items are specific for sub-typing depression into typical vs. atypical depression. Method: Our previous study using exploratory factor analysis on HAM-D17 has been re-analyzed with PCA and the results have been compared to a dataset from another randomized prospective study. Results: PCA showed that the first principal component was a general factor covering depression disability with factor loadings very similar to those obtained in the STAR*D study. The second principal component was a bi-directional factor contrasting typical vs. atypical depression symptoms. Varimax rotation gave no new insight into the factor structure of HAM-D17. Conclusion: With scales like the HAM-D17, it is very important to make a proper clinical interpretation of the PCA before attempting any form of exploratory factor analysis. For the HAM-D17, our results indicate that profile scores are needed because the total score of all 17 items in the HAM-D17 does not give sufficient information.
Revista Brasileira De Psiquiatria, 2013, Vol 35, Issue 4, p. 360-3