1. Primary objectives
To evaluate clinically meaningful benefits of interventions used to treat clinically significant obsessive compulsive symptoms occurring in people with schizophrenia with regard to global improvement, changes in mental state, hospitalisation, behaviour and functioning in the short term (less than six weeks), medium term (six weeks to six months) and long term (more than six months).

In this review we specifically addressed the efficacy and safety of the following when used to treat clinically significant obsessive compulsive symptoms occurring in people with schizophrenia:

1.1 Conventional and newer (or atypical) antipsychotic drugs
1.2 Conventional and newer antidepressant drugs
1.3 Any other drug or pharmacologically active substance
1.4 Non-pharmacological interventions

In future versions of this review we will cover the use of psychosurgery, deep brain stimulation or other invasive interventions for this purpose.

2. Secondary objectives
To determine whether these interventions would have a differential effect:
2.1 In people with schizophrenia in whom obsessive compulsive symptoms preceded the onset of symptoms of schizophrenia as opposed to those in whom obsessive compulsive symptoms occurred in the prodromal stages or after the symptoms of schizophrenia were firmly established
2.2 In people with obsessive compulsive symptoms as opposed to obsessive compulsive disorder as defined by diagnostic criteria