Duration of Untreated Illness as a Predictor of Treatment Response and Clinical Course in Generalized Anxiety Disorder

Abstract

The aim of the present study was to investigate the impact of the duration of untreated illness (DUI)-defined as the time elapsing between the onset of generalized anxiety disorder (GAD) and the first adequate pharmacologic treatment-on treatment response and clinical course in a sample of subjects with GAD. One hundred patients with GAD, diagnosed according to Diagnostic and Statistical Manual of Mental Disorders, Fourth Edition-Text Revision criteria, were enrolled and their main demographic and clinical features collected. Patients were then treated with selective serotonin reuptake inhibitors or venlafaxine for 8 weeks in open-label conditions. Treatment response and other clinical variables were analyzed after dividing the sample into two groups according to DUI (DUI <or=12 months and DUI >12 months). When the DUI was computed with respect to the first antidepressant treatment (DUI-AD), a higher improvement (Clinical Global Impressions-Severity of Illness scale) after the pharmacologic treatment was found in the group with a shorter DUI (analysis of variance with repeated measures: time effect F=654.975, P<.001; group effect: F=4.369, P=.039). When computed with respect to the first treatment with benzodiazepines (DUI-BDZ), the two groups did not show any significant difference in treatment response (time effect: F=652.183, P<.001; group effect: F=0.009, P=.924). In addition, patients with a longer DUI (DUI-BDZ or DUI-AD) showed an earlier age at onset, a longer duration of illness and a higher rate of comorbid psychiatric disorders with onset later than GAD. Results from this preliminary study seem to suggest that a shorter DUI-AD may determine a better response to pharmacologic treatment in patients with GAD, and that a longer DUI (DUI-BDZ and DUI-AD) may be associated to a worse clinical course. Further investigation on the relationship between DUI and GAD is needed.