Selective Serotonin Reuptake Inhibitors(SSRIs) are the first line pharmacotherapy for Obsessive-Compulsive Disorder (OCD) according to APA（American Psychological Association）guideline. Nevertheless, a large proportion (40% or more) of patients response only partially or not at all to treatment with a SSRI. On the basis of the existing sparse literature, several pharmacotherapy options for OCD patients who do not respond, or who respond but do not remit, have been outlined in current treatment guidelines. These include 1) treatment with higher than usual doses of an SSRI, 2) switch to a different SSRI, 3) switch to a different class of medication, 4) augmentation with a dopamine blocker, and 5) augmentation with a glutamatergic agent. There is a need for additional data, particularly real-world data, on how best to choose between these options.~This proposed Randomized Controlled Trial (RCT) study is a multi-center clinical study with a total of 13 centers that specialize in OCD patients. A randomized block design will be used in this study and all eligible participants accepted into this study will undergo an initial course of pharmacotherapy (phase I), and non-remmitters will be randomly allocated to five treatment arms (phase II). In phase I all participants will be treated with sertraline for 12 weeks.In phase II,The 5 arms will comprise 1) treatment with higher than usual doses of sertraline, 2) switch to fluvoxamine, 3) switch to venlafaxine, 4) augmentation with memantine, and 5) augmentation with aripiprazole. Clinicians and patients will know which treatment arm is being employed, but raters will be kept blind to treatment group.
This study includes a sequenced clinical trial in order to assess the efficacy of several switching or augment strategies when initial treatment is ineffective，and to provide strong evidence for clinical practice and international guidelines for Obsessive-Compulsive Disorder treatments.