Duration of untreated illness as a predictor of treatment response and clinical course in generalized anxiety disorder

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 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.