Abstract T MP92: Patient Valuation of Each Level of the Modified Rankin Global Disability Scale: Insights from the Stroke Impact Scale
Background: The modified Rankin Scale (mRS) assessment of global disability is the most commonly used primary endpoint in acute stroke clinical trials and is endorsed for use by US and European drug/device regulatory authorities. However, the mRS is an ordinal scale with ranks an unknown distance apart, hampering identification of minimally clinically important differences in scale outcome distributions. The Stroke Therapy Academic Industry Roundtable and other authorities have called for studies to assign utility weights to each scale level, permitting construction of a “utility-weighted mRS”.
Methods: Consecutive patients undergoing 3 month final outcome visits in the NIH FAST-MAG phase 3 trial were assessed with the mRS and the Stroke Impact Scale, a patient-reported, stroke specific quality of life instrument. The SIS has 8 subscales, assessing different outcome dimensions.
Results: Among 44 alive patients, mean age was 71.9 (SD±13.9), 68% were male, and entry NIHSS was 9.3 (SD±8.6). At 90d, the median mRS was 1 (IQR 0 - 3, lower better). On the SIS patient global judgment of recovery, the 90d median value was 80 (IQR, 60-95, higher better). Score distributions of the 8 SIS functioning domains showed varied patterns across the 6 Rankin levels. At low mRS scores, SIS-QOL scores were modestly lowered in the domains of strength, emotion, activities of daily living, and social participation; lower SIS-QOL in the domains of memory and thinking, communication, and mobility only began to accrue at moderate to severe mRS scores. Utility weights for the mRS, derived from a cross-dimension average SIS score, were: mRS 0 - 0.95, mRS 1 - 0.90; mRS 2 - 0.74; mRS 3 - 0.67; mRS 4 - 0.44; mRS 5 - 0.36. The utility values were monotonic, with natural clusters at mRS 0-1, mRS 2-3, and mRS 4-5.
Conclusion: Mild scores on the modified Rankin Scale are particularly associated with quality of life deficits in the domains of strength, emotion, activities of daily living, and social participation, while more severe mRS abnormalities compromise QOL across all domains of functioning. Utility values for the modified Rankin Scale derived from the Stroke Impact Scale show a decrement with each mRS level, with a natural tetrachotomization of the mRS at 0-1, 2-3, 4-5, and 6.
Author Disclosures: N.N. Chaisinanunkul: None. S. Starkman: None. S.A. Hamilton: None. F. Chatfield: None. R.A. Conwit: None. J.L. Saver: None.
- © 2014 by American Heart Association, Inc.