OPTIMAL TREATMENT FOR OCD (OTO): A RANDOMISED CONTROLLED FEASIBILITY TRIAL COMPARING THE CLINICAL AND COST EFFECTIVENESS OF COGNITIVE BEHAVIOURAL THERAPY (CBT) AND SELECTIVE SEROTONIN REUPTAKE INHIBITORS (SSRI) AND THEIR COMBINATION IN THE MANAGEMENT OF OBSESSIVE COMPULSIVE DISORDER

Abstract

Background Established treatments for Obsessive Compulsive Disorder (OCD) include cognitive behavioural psychotherapy (CBT) and selective serotonin reuptake inhibitor (SSRI) medication. Combining CBT with SSRI may be superior to either monotherapy, but few studies have addressed this question in adults with OCD. Aim Optimal Treatment for OCD (OTO) is a feasibility study aimed to inform the design of a definitive trial of sufficient size to provide accurate information about the cost-effectiveness of each treatment approach. Design The study took place at three centres. Participants were community-based service-users aged 18-65y with OCD of at least moderate severity and a duration of symptoms >1 year. Out of 258 potential participants, 66 were screened and 49 entered the study and were randomly assigned to CBT (n=16), SSRI (n=18) or SSRI+ CBT (combination; n=15). Sertraline (50-200mg/d) was given as the SSRI for 52 weeks. Sixteen hours’ manualised individual CBT was delivered over 8 weeks with 4 additional hour-long follow-up sessions. Regular assessments were made by researchers ‘blinded’ to the treatment allocation for 52 weeks. A preliminary health economic evaluation was made using standardised measures of resource use and the EQ-5D-3L. Results At baseline the mean total Y-BOCS across all groups was 26.7 (SD =5.9). 29 patients completed 16 weeks of treatment, with adequate adherence to allocated treatments. At week 16, for participants remaining in the study, there was evidence of improvement (all patients’ mean total YBOCS =18.4 (8.9)). Combination treatment (n=13) was associated with the largest improvement, sertraline (n=7) the next largest and CBT (n=9) the smallest. Symptomatic improvement continued to 52 weeks, but participant discontinuation made it not possible to perform further reliable between-treatment comparisons. Compared to sertraline monotherapy, the mean costs were higher for the CBT monotherapy, and the combined group. The mean QALY score was greater for sertraline monotherapy when compared with CBT monotherapy and when compared with the combined group. Eleven of a total of 288 adverse events were considered to be severe. Three serious adverse events were reported. One was a suicide attempt, which was considered to be possibly related to treatment, and 2 were hospital admissions for termination of pregnancy which were not related. Conclusions SSRI with CBT may offer the most clinically effective treatment (especially over CBT), and SSRI monotherapy the most cost-effective treatment. Implications If the superiority of SSRI in OCD were to be replicated in a future study, there would be potential for large cost savings to health services. However the small size of the current study means that the conclusions drawn have to be treated with caution, and further research would thereby be of value. Our study confirms that a definitive study can be conducted.