Table 5Key Assumptions of the Submitted Economic Evaluation

Sponsor’s key assumptionCADTH comment
Baseline characteristics of the modelled population reflect the Canadian population.Appropriate.
No stopping rule for satralizumab was considered.Appropriate. The expert panel consulted by CADTH noted that administration of satralizumab would be continued despite relapse or significant deficits accumulated by patients over time. Satralizumab would be discontinued only if patients experienced severe side effects or debilitating disability.
No treatment waning effect was assumed.Potentially appropriate. There is no evidence to suggest that treatment effects would wane over the model time horizon, as indicated by CADTH’s clinical expert, but this remains an area of uncertainty given the duration in which clinical evidence is available.
No treatment discontinuation for maintenance IST.Appropriate. CADTH’s clinical expert indicated that existing maintenance IST would continue to be provided to patients if they were responding well to therapy without serious adverse effects.
Relapse duration and recovery are unaffected by the treatment.Appropriate. There is no clinical evidence to suggest that satralizumab may impact relapse duration and recovery.
Increased risk of mortality in NMOSD patients compared with patients with MS.Likely appropriate. CADTH’s clinical expert indicated that NMOSD is a more aggressive and debilitating disease than MS. As noted in CADTH’s Clinical Review, relapses in NMOSD can result in blindness, paraplegia, and increased overall mortality.
Assumed that the likelihood of experiencing an optic neuritis attack was the same across the spectrum of EDSS health states < 6 but differed for EDSS health states ≥ 6. An additional disutility for severe visual impairment was applied for individuals with an EDSS health state ≥ 6.Potentially appropriate. As indicated by CADTH’s clinical expert, the EDSS scale does not appropriately address vision loss and overvalues ambulation. The sponsor addressed this limitation of the EDSS scale by applying an additional disutility for severe visual impairment across EDSS health states 6 to 9.

EDSS = Expanded Disability Status Scale; IST = immunosuppressive therapy. MS = multiple sclerosis; NMOSD = neuromyelitis optica spectrum disorder.

From: Economic Review

Cover of Pharmacoeconomic Report: Satralizumab (Enspryng)
Pharmacoeconomic Report: Satralizumab (Enspryng): (Hoffmann-La Roche Limited): Indication: Neuromyelitis optica spectrum disorder [Internet].
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