Side Effects to Antidepressant Treatment in Patients With Depression and Comorbid Panic Disorder.

Objective: Side effects to antidepressant medication can affect the efficacy of treatment, but few predictors foretell who experiences side effects and which side effects they experience. This secondary data analysis examined whether depressed patients with comorbid panic disorder were more likely to experience side effects than those without panic disorder. The study also examined whether greater burden of side effects predicted a poorer treatment course for patients with panic disorder than those without panic disorder. To examine the specificity of these effects, analyses also examined 2 other anxiety disorders-social phobia and generalized anxiety disorder (GAD).

Methods: Between 2002 and 2006, a large sample (N = 808) of chronically depressed individuals (assessed using the Structured Clinical Interview for DSM-IV-TR Axis I Disorders [SCID-IV]) received antidepressants according to a predetermined algorithm for 12 weeks. Every 2 weeks, depressive symptoms (per the Hamilton Depression Rating Scale) and side effects (specific side effects as well as several indicators of side effect burden) were assessed.

Results: Lifetime diagnosis of panic disorder (assessed using the SCID-IV) at baseline was associated with higher likelihood of gastrointestinal (OR = 1.6 [95% CI, 1.0-2.6]), cardiac (OR = 1.8 [95% CI, 1.1-3.1]), neurologic (OR = 2.6 [95% CI, 1.6-4.2]), and genitourinary side effects (OR = 3.0 [95% CI, 1.7-5.3]) during treatment. Increases in side effect frequency, intensity, and impairment over time were more strongly associated with increases in depressive symptoms for patients with panic disorder compared to those without panic disorder. Neither social phobia nor GAD was associated with these effects.

Conclusions: Potentially due to heighte​ned interoceptive awareness of changes in their body, chronically depressed individuals with panic disorder may be at greater risk than those without panic disorder for antidepressant side effects and to experience a worsening of depressive symptoms as a result of these side effects over time.

Trial Registration: ClinicalTrials.gov identifier: NCT00057551​.