Mapping the mRS Into the EQ-5D-5L in Patients With Ischemic Stroke

Area of Science:

• Health Economics
• Clinical Outcomes Research
• Psychometrics

Background:

• Health-related quality of life (HRQoL) instruments are crucial for assessing patient outcomes.
• Translating between different HRQoL measures, like the modified Rankin Scale (mRS) and EQ-5D, is essential for consistent cost-effectiveness analyses.
• Quality-adjusted life years (QALYs) require utility values, often derived from instruments like EQ-5D.

Purpose of the Study:

• To translate modified Rankin Scale (mRS) scores at 3 months post-ischemic stroke into 5-level EQ-5D utility values.
• To enable the derivation of quality-adjusted life years (QALYs) for cost-effectiveness studies in stroke.
• To establish a reliable mapping algorithm for converting mRS to EQ-5D utility values.

Main Methods:

• Pooled data from three Dutch phase III ischemic stroke clinical trials (MR CLEAN-NO-IV, MR CLEAN-MED, MR CLEAN-LATE).
• Assessed mRS scores and 5-level EQ-5D via telephone interview at 3 months poststroke.
• Explored various direct and indirect mapping algorithms, including multinomial logit models, and validated results in an external dataset.

Main Results:

• The EQ-5D dimensions of self-care, daily activities, and mobility showed the strongest correlation with mRS scores (ρ=0.46-0.70).
• Indirect mapping using a multinomial logit model was identified as the preferred algorithm.
• Mean fitted utility values per mRS score ranged from 0.947 (mRS 0) to 0.147 (mRS 5).

Conclusions:

• The derived mean utility weights facilitate direct estimation of QALYs from mRS scores.
• The multinomial logit model can derive utility values for new datasets, adaptable to country-specific tariffs.
• These results are highly applicable for informing cost-effectiveness analyses in stroke care.