The Pseudoscience of Lithium and Suicide: Reanalysis of a Misleading Meta-analysis

By manipulating inclusion criteria, one can prove whatever point one wishes in meta-analysis. This critique examines a recent meta-analysis claiming lithium ineffectiveness for suicidality, based on three biased features: inclusion of many large studies specifically designed to exclude suicidality, producing zero suicide outcomes in all groups ( = 1856), thereby artificially decreasing statistical significance; arbitrary exclusion of all trials prior to the year 2000, thereby excluding two randomized clinical trials which demonstrated benefit for lithium; and underreporting of placebo suicide events in a recent randomized trial. It thereby created a smaller effect size (two suicides with lithium versus five with placebo = RR = 0.42), though still beneficial for lithium, and a larger denominator of no events (total for included studies = 2578), leading to the claim of statistical non-significance (95% confidence intervals (CIs) 0.1-4.5). The same literature can be analyzed including the two excluded older studies, and including the two placebo deaths in the recent trial, producing a larger effect size (two suicides with lithium versus nine with placebo, RR = 0.25). Furthermore, uninformative studies with no events could be excluded (total for included studies = 1203), as is standard practice in meta-analysis, producing statistically significant results (95% CIs 0.05, 0.83). This more complete, more accurate, and less biased meta-analysis is provided in this article.In short, including all studies with non-zero suicide outcomes, there is clear benefit for lithium. The recent meta-analysis is a classic example of pseudoscience, using scientific technique superficially to confirm, rather than refute, one's own opinions.