Outcome Assessment and Clinical Improvement in Panic Disorder: Evidence From a Randomized Controlled Trial of Fluoxetine and Placebo

Medical University of South Carolina, Charleston, USA.
American Journal of Psychiatry (Impact Factor: 12.3). 12/1998; 155(11):1570-7. DOI: 10.1176/ajp.155.11.1570
Source: PubMed


Although panic attacks account for only a portion of the morbidity of panic disorder and panic attack frequency assessments are unreliable, studies of drug efficacy in panic disorder have generally used reduction in panic attack frequency as the primary measure of improvement. The authors studied the efficacy of fluoxetine treatment in panic disorder and measured the relative contributions of changes in symptoms to overall improvement.
Patients with a diagnosis of panic disorder (N = 243) were randomly assigned to treatment with 10 or 20 mg/day of fluoxetine or placebo. Primary outcome measures were change in panic attack frequency and clinician-rated Clinical Global Impression improvement scores. Other assessments included a panic attack inventory, clinician-rated and patient-rated versions of the Panic and Phobic Disorder Change Scale, a phobia rating scale, the Hamilton Anxiety Rating Scale, the 21-item Hamilton Depression Rating Scale, and the Sheehan Disability Scale. Correlations were determined between outcomes in individual symptom domains and overall clinical outcome.
Fluoxetine, particularly the 20-mg/day dose, was associated with more improvement than was placebo in patients with panic disorder across multiple symptom measures, including global improvement, total panic attack frequency, phobic symptoms, and functional impairment. Global improvement was most highly correlated with reductions in overall anxiety and phobic symptoms and least correlated with reduction in panic attacks. Fluoxetine treatment for panic disorder was well tolerated, with a safety profile consistent with that observed for fluoxetine in other disorders.
These data provide support for the efficacy and safety of fluoxetine treatment in reducing panic attacks, phobic symptoms, anxiety, and depressive symptoms in patients with panic disorder. Reductions in panic attack frequency in subjects given either fluoxetine or placebo were less closely related to overall clinical improvement than reductions in phobic avoidance, anxiety, depressive symptoms, and functional impairment, suggesting that outcome measures in this disorder should be more broadly based.

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    • "Furthermore, Telch et al. (1995) found that changes in anxiety and avoidance predicted functioning at both post-treatment and six-month follow-up. However, other studies found no correlation between symptom reduction and QOL, both in panic disorder and obsessivecompulsive disorder (Michelson et al., 1998; Tenney et al., 2003). "
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    • "First, the LCI only assessed the course of panic attacks, but the course of other aspects such as agoraphobia, anticipatory anxiety and level of functioning were not considered as these aspects were not assessed in the LCI. Including multiple outcome criteria is advised in PD research (Roy-Byrne & Cowley, 1994/1995 ; Shear & Maser, 1994 ; van Balkom et al. 2000) because, for example, overall improvement may be more closely related to other aspects than to panic attacks (Michelson et al. 1998). Second, because of the study design, subjects with the most chronic panic (i.e. "
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