Course trajectories of unipolar depressive disorders identified by Latent Class Growth Analysis Chapter 6

Background Current classification of unipolar depression reflects the idea that prognosis is essential. However, do DSM-categories of Major Depressive Disorder (MDD), Dysthymic Disorder and Double Depression indeed adequately represent clinically relevant course trajectories of unipolar depression? Our aim was to test DSM-categories (MDD, Dysthymic Disorder and Double Depression) in comparison with empirically derived prognostic categories, using a prospectively followed cohort of depressed patients. Methods A large sample (n=804) of outpatients with unipolar depression were derived from a prospective cohort study (NESDA). Using Latent Class Growth Analysis (LCGA) empirically derived two-year course trajectories were constructed. These were compared with DSMdiagnoses and a wider set of putative predictors for class membership. Results Five course trajectories were identified, ranging from mild severity and rapid remission to high severity and chronic course trajectory. Contrary to expectations, over 50% of Dysthymia and Double Depression were allocated to classes with favorable course trajectories, suggesting that current DSM-categories do not adequately represent course trajectories. The class with the most favorable course trajectory differed on a number of characteristics from other classes (younger age, more females, less childhood adversity, less somatic illnesses, lower neuroticism, higher extraversion). Older age, earlier age of onset and lower extraversion predicted poorest course trajectory. Conclusion MDD, Dysthymia and Double Depression did not adequately match empirically derived course trajectories for unipolar depression. For the future classification of unipolar depression, it may be wise to retain the larger, heterogeneous category of unipolar depression, adopting cross-cutting dimensions of severity and duration to further characterize patients. Didi Rhebergen Femke Lamers Jan Spijker Ron de Graaf Aartjan TF Beekman Brenda WJH Penninx Published in: Psychological Medicine 2011; 7: 1-14. Course trajectories of unipolar depressive disorders | 103