Cost-effectiveness of mirtazapine relative to amitriptyline in the treatment of moderate and severe depression in France.

Authors: MCJ Brown, JMT van Loon & JF Guest.
Source: European Journal of Psychiatry 1999; 13(4): 197-208.

ABSTRACT

This study estimated the cost-effectiveness of mirtazapine, compared to amitriptyline, in the management of moderate and severe depression among outpatients in France, from the perspective of the Social Security Fund.

The economic analysis was based on significant clinical differences obtained from a meta-analysis of four randomised trials comparing mirtazapine with amitriptyline in the US. A decision model of the treatment paths and associated resource use attributable to managing moderate and severe depression in France was developed from the trial data, information on French clinical practice obtained from interviews with a French Delphi panel and published literature. Decision analysis techniques enabled the expected direct Social Security costs and the expected indirect societal costs due to lost productivity to be estimated over 28 weeks at 1995/96 prices. This study was critically appraised by an Expert Panel who endorsed and supported the analysis and its assumptions.

Using mirtazapine instead of amitriptyline for 28 weeks increased the proportion of successfully treated patients by 21% (from 19.2% to 23.2%) and reduced the expected Social Security cost from FF22,310 to FF23,096. Consequently, the expected direct cost per patient successfully treated with mirtazapine was FF96,263 compared to FF120,475 for an amitriptyline-treated patient. Patients treated with mirtazapine and amitriptyline for 28 weeks were expected to miss 17.49 and 18.37 weeks of work respectively, due to their depression. Hence, the expected indirect cost to French Society over this period was estimated to be FF96,507 and FF101,321 per patient respectively. The expected cost-differences were largely accounted for by the difference in the cost of managing adverse events and the Social Security payments made to patients during their time off work. Social Security payments were the main cost driver, accounting for up to 86% of the expected direct cost per patient. In contrast, the acquisition costs of antidepressants accounted for between 1% and 3% of the expected direct cost per patient.

The analysis used an acquisition cost (public price) of FF8.98 per 30mg of mirtazapine. Sensitivity analyses showed that across a range of acquisition costs for mirtazapine, up to FF15 per 30mg, mirtazapine remained cost-effective relative to amitriptyline.
In conclusion, this study demonstrated that despite the differences in acquisition costs, mirtazapine is a cost-effective antidepressant compared to amitriptyline in the management of moderate and severe depression in France.