PREDICTORS OF DRUG-TREATMENT RESPONSE IN OBSESSIVE-COMPULSIVE DISORDER

Background: Although a large body of evidence indicates the efficacy o f pharmacotherapy in the treatment of obsessive-compulsive disorder (O CD), a considerable percentage of these patients do not respond. Very few studies focus on factors related to treatment response of OCD. The purpose of this study was to investigate which clinical factors are r elated to drug treatment response in OCD. Method: We examined 53 OCD p atients treated with either clomipramine or fluoxetine for a period of 6 months, dividing the sample into ''responders'' and ''nonresponders '' to treatment. At admission, patients were evaluated using a semistr uctured clinical interview, the Yale-Brown Obsessive Compulsive Scale (Y-BOCS), the Hamilton Rating Scale for Depression, and the Hamilton R ating Scale for Anxiety. We then compared acute-phase patient characte ristics and response to drug treatment. Response was defined as a decr ease of at least 40% in the Y-BOCS total score and a rating of ''impro ved'' or ''very improved'' on the Clinical Global Impressions scale wi thin 16 weeks of treatment and maintained over three consecutive evalu ations. Results: By the sixth month of treatment, 31 patients (58.5%) responded to either clomipramine or fluoxetine. Nonresponders had lowe r age at onset and longer duration of the disorder; in addition, they showed higher frequency of compulsions, washing rituals, chronic cours e, concomitant schizotypal personality disorder, and previous hospital izations. A worse response to drug treatment was predicted in a stepwi se multiple regression by (1) concomitant schizotypal personality diso rder, (2) presence of compulsions, and (3) longer illness length. Conc lusion: Our findings suggest that there are distinct types of OCD with respect to drug treatment response. They provide indirect evidence of treatment specificity by identifying characteristics responsive to di fferent modalities, which may be of value in the selection of patients for alternative treatments.