A pharmacoeconomic evaluation of escitalopram versus citalopram in the treatment of severe depression in the United Kingdom

Abstract

Background: Severe depression can increase the risk of psychiatric hospitalization, as well as inpatient and outpatient care; it may also lead to long-term absenteeism from work. However, the cost-effectiveness of antidepressant therapy for severe depression has been little studied. Objective: The aim of this work was to investigate the cost-effectiveness of escitalopram compared with citalopram in patients with severe depression (Montgomery-Åsberg Depression Rating Scale [MADRS] total score ≥30) in the United Kingdom. Methods: A probabilistic decision tree with a 6-month time horizon was adapted to the UK setting. The model incorporated clinical data, resource use directly related with care of severe depression, and lost productivity costs due to absenteeism. Primary results were remission (MADRS ≤12) and costs (in year-2003 British pounds [£1.00 = US $0.62 in January 2003]) of treatment calculated from the perspectives of UK society and the National Health Service (NHS). Secondary outcome was first-line success of treatment (ie, remission [MADRS ≤12] without switch of drug). Remission, discontinuation, and response rates were derived from a meta-analysis of 506 patients with severe depression and extrapolated to 6 months. Standard UK price lists and literature were used to identify costs of resources. Societal costs of lost productivity were calculated using the human capital approach. Results: Treatment of patients with escitalopram instead of citalopram rendered a higher overall remission rate (relative difference, 10.3%) and first-line success rate (relative difference, 35.4%). The mean cost per successfully treated patient was 15.7% (£146) lower for escitalopram (£786 [range, £702–£876]) compared with citalopram (£932 [range, £843–£1028]) from the NHS perspective and 15.6% (£238) lower for escitalopram (£1283 [range, £1157–£1419]) than for citalopram (£1521 [range, £1383–£1675]) from the societal perspective. The mean cost per severely depressed patient treated (overall study group) was £32 lower for escitalopram (£422 [range, £404–£441]) than citalopram (£454 [range, £436–£471]) from an NHS perspective and £50 lower for escitalopram (£690 [range, £665–£714]) than citalopram (£740 [range, £715–£767]) from the societal perspective. Using multivariate sensitivity analyses, we found that, in >99.8% of the cases, escitalopram was dominant from both perspectives at all ranges of probabilities tested. A sensitivity analysis on the acquisition cost of citalopram verified that, from the societal perspective, escitalopram remained the dominant strategy, even at a cost of £0.00 for citalopram. Conclusions: These results suggest that escitalopram is a cost-saving alternative to citalopram for the treatment of severe depression in the United Kingdom from the perspectives of both the NHS and society. Therefore, a possible advantage may exist at the population level in the treatment of severe depression with escitalopram in the United Kingdom.