Socio-economic aspects of the testing for antibodies in MS-patients under interferon therapy in Austria: a cost of illness study.

Background: According to EU-guidelines testing patients on interferon-beta (IFNb) for the presence of neutralising antibodies (NAb) is recommended; IFNb treatment efficacy of NAb-positive patients equals that of placebo-treated patients. Economic impact of NAb testing in MS patients has not been explored yet. The aim of this analysis is to estimate the impact of NAb testing in RRMS-patients on Austria׳s health-care-system.

Methods: A decision-analytic model over 5 years was performed. The cost effectiveness of NAb testing versus no testing was evaluated. The model considers switching after relapse and withdrawal. All direct costs are based on Austrian data from 2013 and were discounted at 5% per year. The efficacy outcome measure was "relapse free". Clinical data and resource use were determined by literature.

Results: Total costs for all Austrian MS-patients on IFNb-therapy with testing amount to 187,554,021€ over 5 years; without testing is 175,091,300 €. Costs per relapse avoided over 5 years were 90,075€ in the NAb testing arm, and 99,535€ in the no NAb test arm, resulting in a difference of 9460€ in favour of routine NAb testing. Considering all 3590 IFNb-treated patients 2082 relapses can be avoided in the NAb testing arm versus 1759 in the no-testing arm within 5 years. Testing for NAb leads to costs per relapse avoided of 18,015€ per year versus 19,907€ when no tests are done.

Conclusion: The results suggest that NAb testing reduces relapses and associated costs.