Abstract TP77: Stroke Rank Order Correlation but Moderate Absolute Value Drift Between Early Day 2/4 and Day 90 Stroke Outcome Scales: mRS, BI, and NIHSS

Abstract

Background: In acute stroke trials, the three most commonly used outcome scales are the modified Rankin Scale (mRS) to assess global disability, the Barthel Index (BI) to assess instrumental activities of daily living, and the National Institutes of Health Stroke Scale (NIHSS) to assess neurologic deficit severity. The value of early scale assessments to forecast 3-month disability outcomes has not been formally investigated. Methods: In this cohort study of patients with acute ischemic stroke (AIS) in the NIH Field Administration of Stroke Therapy- Magnesium (FAST-MAG) Phase 3 trial, we assessed the performance of day 2, 4, and 30, BI, and NIHSS to forecast their day 90 counterparts using correlation coefficients and absolute differences. Results: Among 1041 with AIS, mRS on d2 (r=0.67) and d4 (r=0.72) showed strong correlation and mRS on d30 (r=0.89) very strong correlation with d90 mRS. However, value shifts were common. For example, d4 mRS exactly matched d90 mRS in only 35.8%, while 40.2 % had better and 24 % had worse outcomes. D4 BI exactly matched d90 BI in only 41.2%, while 48.5% had better and 11.2% had worse outcomes. For NIHSS, d4 exactly matched d90 value in only 20.5%, while 57.9% had better and 22.6% had worse outcomes. (Figure) Conclusions: mRS, BI, and NIHSS outcomes as early as days 2 and 4 post-stroke correlate strongly with their longterm, 3m outcome rank ordering but only moderately with their absolute values. Delineation of this outcome trajectory provides a foundation for imputing final patient disability, ADL, and deficit outcomes in clinical trials and quality improvement programs.