Clinical characteristics of response to fluoxetine treatment of obsessive-compulsive disorder

Fluoxetine is effective in treating obsessive-compulsive disorder (OCD). Nonetheless, a substantial number of patients do not respond or have only partial improvement. Data generated by a multicenter, placebo-controlled, fixed-dose trial of fluoxetine were reanalyzed to identify characteristics of responders. Multiple regression methods were used to evaluate the relationship between therapeutic response and baseline measures such as severity of symptoms, type of symptoms (obsessions, compulsions, depression), course of illness, previous treatment, age of onset, and other demographic factors (age, race, and sex). Fluoxetine was more effective than placebo on all outcome measures. A 60-mg dosage was associated with a greater drop in Yale-Brown Obsessive-Compulsive Scale total score and a greater drop in Compulsion items than a 20-mg dosage. Response rates and overall improvement were greatest for patients with a history of remissions, with no previous drug treatment or with only prior behavior therapy, with more severe OCD (especially with greater interference and distress from obsessions), or with either low or high Hamilton Rating Scale for Depression scores. This study did not detect any associations between response and current age, age of OCD onset, gender, and race. None of the demographic or clinical factors evaluated was found to be related to improvement in the placebo group.