In the past decades the cost-effectiveness of new effective disease-modifying therapies (DMTs) for Relapsing Remitting Multiple Sclerosis (RRMS) form was assessed through decision analytical models. Recently, new treatment option for the Primary Progressive (PPMS) form was developed. Aim of this work was assessing the similarities and differences of PPMS and RRMS and their impact in the development of decision analytical model for PPMS.

Literature review was performed to retrieve information on natural history of PPMS and RRMS and impact of DMTs agents on the progression of these conditions. Further, a review of the published cost-effectiveness models for RRMS was performed. Based on these data, an analysis on the difference and similarities between the two MS forms that could have an impact on the development of decision analytical model for PPMS was performed.

Based on the analysis, similar structure model used for RRMS could be applied for PPMS. Health states of the model could be based on Expanded Disability Status Scale score as already done for RRMS. The relapse events considered for RRMS should not be included in PPMS model, and no possibility to develop another form, as the Secondary Progressive, should be included. While RRMS models should include at least a second line treatment option due to alternative DMTs available, only first treatment line should be considered for PPMS. Assessing data available to populate the model, poor data on the natural history, utility and cost associated to PPMS were available and assumption or expert opinions will be needed to overcome the lack of robust data.

A decision analytical model for PPMS can use a similar structure used in the models for RRMS. However, more robust data on PPMS and some structural change are needed to provide a good tool to assess cost-effectiveness of DMTS in PPMS.