Open-label evaluation of venlafaxine sustained release in outpatients with generalized anxiety disorder with comorbid major depression or dysthymia: effectiveness,tolerability and predictors of response

In a setting of routine clinical practice, 32 outpatients with generalized anxiety disorder (GAD) and major depression (MD) (n = 21) or dysthymia (n = 11), according to DSM-IV criteria, were consecutively treated with flexible dosages of sustained-release venlafaxine (SR-VF) for at least 8 weeks. In a 16-week follow-up, SR-VF daily dose could be modified on the basis of the therapeutic response and of the side effect profile. Symptomatological modifications were explored by means of the Clinical Global Impression (CGI) scale, Hamilton Rating Scale for Depression (HAM-D), and Hamilton Anxiety Scale (HAM-A). SR-VF was well tolerated and only 2 patients interrupted the treatment before 24 weeks; the mean final dose +/- SD was 135.5 +/- 71.8 mg (range 75-225); in 26 (81.2%) patients, a statistically significant response was observed in depressive symptomatology within the first 8 weeks. The mean total score of HAM-D showed a significant reduction during the first 8 weeks of treatment, while the mean total score of HAM-A did not present a significant reduction until week 24. In patients with MD, a statistically significant response was observed after the first 8 weeks, while the reduction of the anxiety scores required more time and, in some cases, did not appear at all. Conversely, in patients with GAD and dysthymia, anxious and depressive symptomatology improved simultaneously. Stepwise multiple regression indicated that the improvement of depression is negatively related to a high score of CGI anxiety severity, and the improvement of anxiety is related to the presence of dysthymia and, to a lesser extent, to a short duration of the illness. Our data confirm the effectiveness and tolerability of SR-VF in mixed anxiety-depressive states. The differential response suggests a pathophysiologic and clinical distinction between GAD with comorbid MD or dysthymia.