A Cochrane review [Abstract] 1 included 22 studies with a total of 763 patients.Most participants had schizophrenia. One study had a one year duration. Four studies were medium-term, with a duration of 13 to 19 weeks. All of the others were in the 'short-term' category, lasting between 3 and 8 weeks.Three small studies comparing lithium with placebo as the sole treatment showed no difference in any of the outcomes analysed.In 8 studies (n=270) comparing lithium with antipsychotic drugs as the sole treatment, more participants in the lithium group left the studies early (RR 1.77, 95% CI 1.01 to 3.11).Thirteen studies examined whether the augmentation of antipsychotic drugs with lithium is more effective than antipsychotic drugs alone. More participants who received lithium augmentation had a clinically significant response (RR 1.81, 95% CI 1.10 to 2.97; 10 RCTs, n=396). However, this effect became non-significant when the following studies were excluded: patients with schizoaffective disorders (RR 1.64, 95% CI 0.95 to 2.81; 7 RCTs; n = 272), non-double-blind studies (RR 1.82, 95% CI 0.84 to 3.96; 7 RCTs; n = 224), or studies with high attrition (RR 1.67, CI 0.93 to 3.00; 9 RCTs; n = 355). The overall acceptability of treatment (measured by the number of participants leaving the studies early) was not significantly different between the groups (RR 1.89, CI 0.93 to 3.84; 11 RCTs; n = 320). Few studies reported on side effects. For example, there were no data on thyroid dysfunction and kidney problems, which are two major and well-known side effects of lithium.
Comment: The quality of evidence is downgraded by study quality (unclear allocation concealment, high drop-out rate), imprecise results (few patients in each study) and indirectness (short follow-up time).
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