Selective serotonin re-uptake inhibitors (SSRIs) versus placebo for obsessive compulsive disorder (OCD)

Obsessive compulsive disorder (OCD) is a common and disabling disorder, which frequently follows a chronic course. It is characterised by intrusive thoughts of imagined harm, which are difficult to dispel, and ritualistic behaviour such as repetitive washing of hands and repetitive checking for risk of harm. Individual randomised controlled trials have demonstrated that antidepressants are effective for OCD. This review summarises all the available evidence for one class of antidepressant drugs, the selective serotonin re-uptake inhibitors (SSRIs) (including citalopram, fluoxetine, fluvoxamine, paroxetine and sertraline) compared to placebo in the treatment of OCD in adults. The review included 17 studies (3097 participants), and showed that SSRIs were effective in reducing the symptoms of OCD. Based on 13 studies (2697 participants), the review showed that people receiving SSRIs were nearly twice as likely as those receiving placebo to achieve clinical response (defined as a 25% or more reduction in symptoms). Indirect comparisons of effectiveness suggested that although individual SSRI drugs were similar in their effectiveness, they differed in terms of their adverse effects. The most common adverse effect reported by participants was nausea. Further studies involving head to head comparisons between different SSRI drugs are required to obtain more reliable information on differences between SSRIs, both in terms of effectiveness and adverse effects.