Randomised controlled trials (RCTs) that compared the effect of add-on antidepressants with placebo on the negative symptoms of chronic schizophrenia were eligible for inclusion. Trials were excluded if the antidepressant was used to treat an explicit comorbid psychiatric disorder (defined in the review), if the antidepressant was not add-on and if the antidepressant was not normally classified as an antidepressant. Relevant outcomes were the scale for the assessment of negative symptoms (SANS), positive and negative syndrome scale (PANSS) and brief psychiatric rating scale (BPRS). Trials that did not meet the quality criteria were excluded.
The included trials studied citalopram, fluoxetine, fluvoxamine, mianserin, mirtazapine, paroxetine, reboxetine, ritanserin, sertraline and trazodone in patients with schizophrenia. Trial duration ranged from four to 12 weeks. Mean age of patients at study entry ranged from 30 to 62 years. Duration of illness varied from four to 34 years. The proportion of males ranged from 23% to 93%. The severity of negative symptoms ranged from 1.73 to 8.21 and the severity of positive symptoms ranged from 0.46 to 5.66.
Two reviewers independently performed study selection. Disagreements were resolved by consultation with a third reviewer.