Generalized anxiety disorder versus panic disorder: participation in controlled efficacy trials

Seventy-one patients with panic disorder (PD) and 46 patients with generalized anxiety disorder (GAD) were studied in relation to their behavior before, during, and after participation in two contemporaneous and procedurally similar double-blind drug efficacy trials. The two groups were administered a battery of assessments aimed at comparing them on the nature and intensity of various symptom domains, social and work-related disability, personality, life events, and previous treatments. The results yielded few significant differences that were not due to definitional factors, most notably a more prevalent history of depression and treatment for depression in the GAD group and a higher rate of pharmacological treatment in the PD group. On the other hand, the two groups behaved in a comparable way in the screening, experimental, and postexperimental phases of the trials. The findings are in support of more similarities than differences between the groups. In addition, the comparable behavior of the two groups throughout the three phases of the trial suggests that differential pretreatment attrition and compliance with placebo-controlled trials may not present major confounding problems in comparative treatment effectiveness studies between GAD and PD diagnostic groups.