The article you requested is

Is Divalproex a Cost Effective Alternative in the Acute and Prophylactic Treatment of Bipolar I Disorder?

J Clin Psychiatry 1997;58(11):495-496 [letter]

Letter to the Editor

Sir: A recent pharmacoeconomic study concluded that divalproex is a less costly treatment than lithium in the acute and prophylactic treatment of patients with bipolar I disorder.

Such a decision-analytic study must rest on hard data, and hard data supporting the prophylactic properties of divalproex are unavailable. The authors did mention that no controlled study assessed the prophylactic efficacy of divalproex, and, to our knowledge, no such study has been published since then.