A Cochrane review [Abstract] 1 included 65 RCTs with a total of 6493 subjects with schizophrenia. The trials, comparing antipsychotic medication with placebo, were published from 1959 to 2011 and their size ranged between 14 and 420 participants. Only four studies lasted two years and only one for three years. Antipsychotic drugs were significantly more effective than placebo in preventing relapse at 7 to 12 months (primary outcome; drug 27%, placebo 64%, RR 0.40, CI 0.33 to 0.49, NNT 3; 24 RCTs, n=2669). Hospitalisation was also reduced, however, the baseline risk was lower (drug 10%, placebo 26%, RR 0.38, CI 0.27 to 0.55, NNT 5; 16 RCTs, n=2090). More participants on placebo group than on antipsychotic drug left the studies early due to any reason (at 7-12 months: drug 38%, placebo 66%, RR 0.55, CI 0.46 to 0.66, NNT 4;18 RCTs, n=2420) and due to inefficacy of treatment (at 7-12 months: drug 20%, placebo 50%, RR 0.36, CI 0.28 to 0.45, NNT 3; 18 RCTs, n=2420). Quality of life was better in drug-treated participants (SMD -0.62, CI -1.15 to -0.09; 3 RCTs, n=527). Conversely, antipsychotic drugs as a group and irrespective of duration, were associated with more movement disorders (e.g. at least one movement disorder: drug 16%, placebo 9%, RR 1.55, CI 1.25 to 1.93, NNTH 25; 22 RCTs, n=3411), sedation (drug 13%, placebo 9%, RR 1.50, CI 1.22 to 1.84, NNTH not significant; 10 RCTs, n=146) and weight gain (drug 10%, placebo 6%, RR 2.07, CI 1.31 to 3.25, NNTH 20; 10 RCTs, n=321). The results of the primary outcome were robust in a number of subgroup, meta-regression and sensitivity analyses, the main exception being that the drug-placebo difference in longer trials was smaller than in shorter trials.
Comment: The quality of the evidence is downgraded by study quality (unclear allocation concealment, short follow-up time) and upgraded by large magnitude of effect.
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