Serum sodium valproate testing: Is it appropriate?

Objective: To assess whether serum sodium valproate (SVP) testing in the hospital setting is being performed according to evidence-based criteria. Design and setting: Retrospective audit of serum SVP concentration measurements performed on inpatients and emergency department patients at The Canberra Hospital from May to July 2005. Main outcome measures: Indication for performing the test, assessed against evidence-based criteria; timing of blood sample collection; whether the test result altered patient management; whether the request form allowed laboratory staff to assess the appropriateness of the test; cost of performing inappropriate tests. Results: We retrieved 211 test results performed on a total of 95 patients. Notes on 89 patients were available for analysis. Based on evidence-based criteria, 15% of tests were done for an appropriate indication and 29% of the samples were taken at an appropriate time. At most (using generous criteria), 57% of test results made a difference to patient management. Forty-four per cent of request forms contained sufficient detail to allow the pathology department to assess the appropriateness of the test. An estimated $13 236 would be spent unnecessarily on SVP testing at our hospital over a 1-year period. Conclusions: Most serum SVP level measurements were requested inappropriately, and many were not taken at the correct time, thereby rendering the results uninterpretable. Better education of requesting clinicians could significantly reduce the number of unnecessary tests and thus reduce the cost to the health service.