A cost-effectiveness analysis of subcutaneous interferon beta-1a 44mcg 3-times a week vs no treatment for patients with clinically isolated syndrome in Sweden

Figures & data

Figure 1. Model schematic. CIS, clinically isolated syndrome; Tx, treatment; EDSS, expanded disability status scale; MS, multiple sclerosis.

Table 1. Heath state costs and utility values by EDSS score.

Disability score	Direct costs (excluding DMDs)	Indirect costs	Utility
EDSS 0	23,359 SEK	53,904 SEK	0.83
EDSS 1	23,359 SEK	53,904 SEK	0.83
EDSS 2	102,418 SEK	113,199 SEK	0.70
EDSS 3	80,857 SEK	190,462 SEK	0.65
EDSS 4	147,339 SEK	127,574 SEK	0.60
EDSS 5	201,243 SEK	190,462 SEK	0.58
EDSS 6	188,665 SEK	188,665 SEK	0.57
EDSS 7	472,562 SEK	222,805 SEK	0.38
EDSS 8	950,514 SEK	247,960 SEK	0.05
EDSS 9	950,514 SEK	247,960 SEK	0.05

EDSS, expanded disability status score; DMD, disease modifying drug.

Note: Costs were obtained in 2005 Euros and converted to 2012 SEK.

Figure 2. Estimated time to MS conversion: treatment vs no treatment.

Table 2. Cost-effectiveness of sc IFN beta-1a tiw vs no treatment.

	sc IFN ß-1a 44 mcg tiw	No treatment	Increment
Total cost (SEK)	7,730,509	8,000,772	−270,263
CIS Tx	304,669	0	304,669
CIS (state)	396,210	219,194	177,015
MS Tx	832,709	882,288	−49,579
MS (state)	6,196,920	6,899,289	−702,369
QALYs	13.79	13.26	0.53
PFLYs	3.51	1.88	1.63
Cost/QALY	–	–	Dominant
Cost/PFLY	–	–	Dominant
Net monetary benefit (NMB)*			535,118

*Using a willingness-to-pay threshold of 500,000 SEK/QALY.

CIS, clinically isolated syndrome; Tx, treatment; MS, multiple sclerosis; QALY, quality-adjusted life year; PFLY, progression-free life year; sc, subcutaneous; IFN, interferon; tiw, 3-times weekly.

Figure 3. One-way sensitivity analysis tornado diagram. Note, this figure illustrates the variation from the base-case net monetary benefit (535,118 SEK) found when individual model parameters were changed. Values in parentheses represent the lower, base-case, and upper values tested in the sensitivity analysis. EDSS, Expanded Disability Status Scale; HR, hazard ratio; IFN, interferon; sc, subcutaneously; SPMS, secondary progressive MS; tiw, 3-times weekly. For ‘McDonald progression approach’, 1 = constant probability of conversion to MS, 2 = parametric extrapolation used in base case. For ‘Utility dataset in use’, 1 = UK dataset²⁶, 2 = Swedish dataset used in base case⁴.

Figure 4. Cost-effectiveness plane showing incremental cost vs incremental QALYs for each PSA iteration.