Just how good is clozapine at treating suicide?

From
http://priory.com/focus14.htm

"
Meltzer, (1999) in the Clozapine and InterSepT study reported a 80-85% reduction in the incidence of suicide in neuroleptic resistant patients on clozapine. 
Walker et al (1997) reported the results of a retrospective analysis of mortality of 67,072 schizophrenic patients receiving clozapine in the interval between April 1 ,1991 and December 31, 1993. The data were acquired from the clozaril national registry. Patients were classified as current, recent, or past clozapine users. The striking finding was that of a dramatic reduction in the incidence of suicide among current users of clozapine. While the incidence of suicide in this cohort was 19% of overall mortality, the patients who completed suicide were primarily those who had stopped using clozapine.
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