Utilization of valproate: Extent of inpatient use in the New York State Office of Mental Health

Objective: To describe the extent and type of use of valproate among hospitalized psychiatric patients. Method: A database containing patient information and drug prescription information for every in-patient within the adult civil facilities of the New York State Office of Mental Health was queried. Results: In 1994, 2,888 of 18,668 in-patients received valproate (15.5%). In 1996, 4,247 of 12,444 in-patients received valproate (34.1%). In 1996, approximately 50% of all patients diagnosed as bipolar or schizoaffective, and 28% of all patients diagnosed with schizophrenia, received valproate. Once started on valproate, over 90% remained on it after 2 weeks, with no difference found in the discontinuation rates between valproic acid or divalproex sodium at the end of the initial 14 day period. Patients received valproate for approximately two-thirds of their hospital stay, at a mean dose of 1400 mg/day. 95% also received concomitant antipsychotics, and 20% received concomitant lithium. Use of lithium and carbamazepine was less in 1996 than in 1994, but the magnitude of this change was much less than the increase in utilization of valproate. Conclusions: From 1994 to 1996 valproate use has more than doubled, and it is being used widely in patients with schizophrenia, an off-label indication for which there is only anecdotal support in the literature. Given the lack of difference in early discontinuation rates, there are probably no dramatic differences in side effects for the two preparations of valproate.