Predictors of response to pharmacotherapy with citalopram in obsessive-compulsive disorder

Although serotonin reuptake inhibitors (SRIs) are the medications of choice in the treatment of obsessive-compulsive disorder (OCD), only 50-60% of patients respond to a single trial of any of these agents. Improved knowledge of the predictors of response to treatment may have important clinical implications. Data from a large randomized placebo-controlled trial of citalopram in OCD was analysed using logistic regression to determine predictors of response. Demographic (age, sex), clinical (OCD severity and duration, depression severity, prior treatment) and trial variables (citalopram dose, treatment duration) were included. Subjects with longer duration of OCD, more severe OCD symptoms or previous selective SRI use were less likely to be responders in the citalopram trial. In contrast, subjects who received adequate medication doses for sufficient periods of time in the citalopram trial were more likely to be responders. Despite greater awareness of OCD in recent years, there is evidence that the disorder continues to be underdiagnosed and undertreated. The data here emphasize the crucial importance of early diagnosis and treatment of OCD, and of pharmacotherapy with appropriate dose and duration.