Structural equation modeling for identifying the drivers of health-related quality of life improvement experienced by patients with migraine receiving eptinezumab.

Background: As new migraine therapies emerge, it is crucial for measures to capture the complexities of health-related quality of life (HRQoL) improvement beyond improvements in monthly migraine day (MMD) reduction. Investigations into the correlations between MMD reduction, symptom management, and HRQoL are lacking, particularly those that focus on improvements in canonical symptoms and improvement in patient-identified most-bothersome symptoms (PI-MBS), in patients treated with eptinezumab. This exploratory analysis identified efficacy measures mediating the effect of eptinezumab on HRQoL improvements in patients with migraine.

Methods: Data from the DELIVER study of patients with 2-4 prior preventive migraine treatment failures (NCT04418765) were inputted to two structural equation models describing sources of HRQoL improvement via Migraine-Specific Quality-of-Life Questionnaire (MSQ) scores. A single latent variable was defined to represent HRQoL and describe the sources of HRQoL in DELIVER. One model included all migraine symptoms while the second model included the PI-MBS as the only migraine symptom. Mediating variables capturing different aspects of efficacy included MMDs, other canonical symptoms, and PI-MBS.

Results: In the first model, reductions in MMDs and other canonical symptoms accounted for 35% (standardized effect size [SES] - 0.11) and 25% (SES - 0.08) of HRQoL improvement, respectively, with 41% (SES - 0.13) of improvement comprising "direct treatment effect," i.e., unexplained by mediators. In the second model, substantial HRQoL improvement with eptinezumab (86%; SES - 0.26) is due to MMD reduction (17%; SES - 0.05) and change in PI-MBS (69%; SES - 0.21).

Conclusions: Improvements in HRQoL experienced by patients treated with eptinezumab can be substantially explained by its effect on migraine frequency and PI-MBS. Therefore, in addition to MMD reduction, healthcare providers should discuss PI-MBS improvements, since this may impact HRQoL. Health technology policymakers should consider implications of these findings in economic evaluation, as they point to alternative measurement of quality-adjusted life years to capture fully treatment benefits in cost-utility analyses.

Trial Registration: ClinicalTrials.gov (Identifier: NCT04418765 ; EudraCT (Identifier: 2019-004497-25; URL: https://www.clinicaltrialsregister.eu/ctr-search/search?query=2019-004497-25 ).