title: Effectiveness of lithium in subjects with treatment-resistant depression and suicide risk: results and lessons of an underpowered randomised clinical trial.
abstract: BACKGROUND
  As lithium treatment might be effective in reducing the risk of deliberate self-harm (DSH) in adult patients with unipolar affective disorders, we designed a pragmatic randomised trial to assess its efficacy in more than 200 patients with treatment-resistant depression. However, we randomised 56 patients only. The aim of this report is therefore twofold: first, to disseminate the results of this underpowered study which may be incorporated into future meta-analytical reviews; second, to analyse some critical aspects of the study which might explain failure to reach the target sample size.
  
  
  METHODS
  We carried out a randomised, parallel group, assessor-blinded superiority clinical trial. Adults with a diagnosis of major depression, an episode of DSH in the previous 12 months and inadequate response to at least two antidepressants given sequentially at an adequate dose for an adequate time for the current depressive episode were allocated to add lithium to usual care (intervention arm) versus usual care alone (control arm). Suicide completion and acts of DSH during the 12 months of follow-up constituted the composite primary outcome.
  
  
  RESULTS
  Of 58 patients screened for inclusion, 29 were allocated to lithium plus usual care and 27 were assigned to usual care without lithium. Six patients in the lithium plus usual care group and seven in the usual care group committed acts of DSH during the follow-up phase. The survival probability did not differ between the two treatment arms (Chi2 = 0.17, p =0.676). With regard to changes in the severity of depressive symptomatology from baseline to endpoint, no significant differences were detected.
  
  
  CONCLUSIONS
  The present study failed to achieve the minimum sample size needed to detect a clinically meaningful difference between the two treatment arms. Consequently, the finding that lithium, in addition to usual care, did not exert a positive effect in terms of reduction of DSH after 12 months of follow-up is likely due to the lack of sufficient statistical power to detect a difference, if a difference existed. The dissemination of the results of this underpowered study will inform future meta-analytical reviews on lithium and suicide-related outcomes.
  
  
  BACKGROUND
  ClinicalTrials.gov identifier: NCT00927550.
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authors.affiliation: Dipartimento di Sanità Pubblica e Medicina di Comunità, Sezione di Psichiatria, Università di Verona, Verona, Italy. corrado.barbui@univr.it.
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authors.lastname: Barbui
mesh_terms: D000328:Adult; D000339:Affect / Q000187:drug effects; D000928:Antidepressive Agents / Q000627:therapeutic use*; D018692:Antimanic Agents / Q000627:therapeutic use*; D014150:Antipsychotic Agents / Q000627:therapeutic use; D003863:Depression / Q000175:diagnosis / Q000188:drug therapy* / Q000401:mortality / Q000523:psychology; D004359:Drug Therapy, Combination; D005260:Female; D006801:Humans; D007558:Italy; D053208:Kaplan-Meier Estimate; D018020:Lithium Compounds / Q000627:therapeutic use*; D008297:Male; D011569:Psychiatric Status Rating Scales; D012107:Research Design; D018401:Sample Size; D012720:Severity of Illness Index; D059020:Suicidal Ideation; D013405:Suicide / Q000523:psychology; D013997:Time Factors; D016896:Treatment Outcome; D000092864:Suicide Prevention
chemical_list: D000928:Antidepressive Agents; D018692:Antimanic Agents; D014150:Antipsychotic Agents; D018020:Lithium Compounds