Relapses after discontinuation of drug associated with increased resistance to treatment in obsessive-compulsive disorder.

The aim of the present study was to determine whether obsessive-compulsive disorder (OCD) patients whose symptoms recur after drug discontinuation respond again when the same drug at the same daily dosage is reinstituted. Eighty-one patients who were responders to a previous 6-month, open-label, noncomparative, acute treatment phase with fixed doses of selective reuptake inhibitors (SRIs) and who relapsed within 6 months of drug discontinuation had the drug to which they responded in the acute phase reinstated at the same daily dose. The reinstitution trial lasted 24 weeks with monthly evaluations (Yale-Brown Obsessive-Compulsive Scale and Clinical Global Improvement). Data obtained in the reinstitution phase were analysed using Pearson's chi-squared test or Fisher's exact test when appropriate. The cumulative percentages of patients who responded in the second trial were compared to those of patients who responded in the acute treatment phase (for each treatment and for all SRIs together) across all evaluation times. When considering all patients together, a lower percentage of responders resulted when SRIs were reinstated: the difference in the cumulative percentage of responders appeared at month 4 and increased at months 5 and 6 (Pearson chi-squared, P = 0.028, P = 0.009 and P < 0.001, respectively). When considering the patients separately according to the SRI used, no differences in the percentages of responders were found at any time. Our results indicate that patients whose symptoms recur after drug discontinuation respond again when the same drug used previously (at the same dosage used in the acute phase) is reinstated, but at a lower degree with respect to the acute treatment. Findings from our study, together with literature data indicating high relapse rates when discontinuing the treatment after the acute phase, support the idea of continuing the treatment in OCD over the long term.