Impact of Pre-Stroke Frailty on Outcome Three Years after Acute Stroke: The Nor-COAST Study

We aimed to explore the predictive value of pre-stroke frailty index (FI) on functional dependency and mortality 3 years after stroke.

Based on the Rockwood 36-item FI score, we calculated the pre-stroke FI from medical conditions recorded at baseline in the multicenter prospective Nor-COAST study 2015-2017. Participants with a FI score and a modified Rankin scale (mRS) 0-6 3 years post-stroke were included in this study. We used logistic regression analysis with unfavorable mRS (over 2 vs. 0-2) at 3 years, or dead within 3 years, as dependent variable, and frailty and pre-stroke mRS, one at a time, and simultaneously, as predictors. The analyses were carried out unadjusted and adjusted for the following variables one at a time: Age, sex, years of education, stroke severity at admission, infections treated with antibiotics and stroke progression. We report odds ratio (OR) per 0.10 increase in FI.

At baseline, the 609 included patients had mean age 72.8 (standard deviation [SD] 11.8), 261 (43%) were females, and had a FI mean score of 0.16 (SD 0.12), range 0-0.69. During 3 years, 138 (23%) had died. Both the FI, and pre-stroke mRS, were strong predictors for unfavorable mRS (OR 4.1 and 2.7) and dead within 3 years (OR 2.2 and 1.7). Only adjusting for age affected the result. The OR for pre-stroke mRS decreased relatively more than the OR for FI when entered as predictors simultaneously.

FI is a stronger predictor than premorbid mRS for prognostication after stroke.