Lithium Treatment Reduces Suicide Risk in Recurrent Major Depressive Disorder

OBJECTIVE: Evidence that clinical treatment reduces suicide risk in major depressive disorder (MDD) is limited and inconsistent. Since lithium shows major antisuicidal effects in bipolar disorders and in heterogeneous mood disorder samples, we evaluated evidence of antisuicidal effects of lithium in patients with recurrent MDD. DATA SOURCES: We searched MEDLINE (January 1966 to April 2006; search terms: lithium, suicide, affective disorder, depression, major depression, and mood disorder) for studies reporting suicides or suicide attempts during treatment with and without lithium in recurrent MDD patients, and we added data for 78 new subjects, provided from the Lucio Bini Mood Disorders Research Center in Sardinia, Italy. Suicide rates were pooled and analyzed by use of incidence-rate ratios (IRRs) and meta-analytic methods. DATA SYNTHESIS: Eight studies involved 329 MDD patients and exposure for 4.56 years (1149 person-years) with, and 6.27 years (1285 person-years) without, lithium. Overall risk of suicides and suicide attempts was 88.5% lower with vs. without lithium: 0.17%/y versus 1.48%/y (IRR = 8.71; 95% CI: 2.10 to 77.2, p = .0005); for completed suicides (85% risk reduction), IRR = 6.77 (95% CI: 1.29 to 66.8, p = .01). Meta-analysis by risk difference and risk ratio supported these findings, and sensitivity analysis yielded similar results with studies omitted serially. CONCLUSIONS: This is the first meta-analysis suggesting antisuicidal effects of lithium in recurrent MDD, similar in magnitude to that found in bipolar disorders.