Duration of untreated illness in panic disorder : a poor outcome risk factor?

Objective: The aim of this naturalistic study was to evaluate the impact of the duration of untreated illness (DUI) on the outcome and treatment response of panic disorder (PD). Methods: Ninety-six outpatients with PD who underwent an 8-week open-label treatment with serotonergic antidepressants were subdivided into two subgroups: those with DUI ≤ 1 year and those with DUI > 1 year. The main baseline demographic and clinical variables were calculated and compared between the two subgroups of patients (chi-square test or t-test for independent samples). The effect of the antipanic medication was evaluated by analysis of variance with repeated measures considering Hamilton Rating Scale for Anxiety, Clinical Global Impression rating scores, and the number of panic attacks/week as the dependent variables (outcome measures), while the subgroups were the independent ones. Comorbidity with onset later than PD was also considered. Results: There were no differences between patients with DUI ≤ 1 year and patients with DUI > 1 year with respect to the outcome measures considered. However, patients with DUI > 1 year (N = 64) had a higher frequency of comorbid major depressive disorder (MDD) with onset later than PD (p = 0.006). Conclusions: Results from this study suggest that the DUI may be a predictor of the development of comorbid MDD in PD. Further investigations on larger samples and with longer follow-up are warranted.