Estimation of resource utilisation difference between lithium and valproate treatment groups from the VALID study

Abstract

Objective:To assess the difference in resource utilisation between lithium and valproate treatment groups from the VALID study.Methods:A modelled economic study was conducted as an appendage to the VALID study, an international, randomised, open-label, parallel-group, 12-week, equivalence study in patients with bipolar I disorder experiencing a manic/mixed episode, compared the efficacy and safety of valproate against that of lithium. The difference in health resource utilisation between the treatment groups was analysed based on information collected from a standardised questionnaire.Results:Efficacy and tolerability of valproate and lithium were shown to be comparable in the management of bipolar disorder in the VALID study. Cost analysis was based on information for 138 (35.5% male, mean age: 37.73 years) and 131 (45.8% male, mean age: 38.98 years) patients from lithium and valproate treatment groups, respectively. The groups differed in the number of hospital visits (503 vs. 421), outpatient visits (15 vs. 2), and number of work days lost (907 vs. 514.5) due to bipolar disorder. All differences were in favour of the valproate treatment group. In the modelled analysis and subsequent sensitivity analyses, the total cost saving was calculated to be US$199,322 (range: US$37,629–$226,903). This would translate into a cost saving of US$1444 per patient, or a cost saving of US$6278 per patient per year (range: US$1185–$7145 per patient per year).Limitations:The present study suffers from the limitations inherent in any economic evaluation that uses data from multicentre clinical trials with potential variations in treatment provision as well as the theoretical bias from an open-label study design. The study sample size had also limited statistical power to detect moderate differences in total medical costs, given the large variances often observed on cost variables.Conclusions:The use of valproate over lithium is likely to result in substantial cost savings to the healthcare system and reduce the financial burden to patients.