Time course of evolution of disability and cause-specific mortality after ischemic stroke: implications for trial design

Journal article

BACKGROUND: Outcome in stroke trials is often based on a 3-month modified Rankin scale (mRS). How 3-month mRS relates to longer-term outcomes will depend on late recovery, delayed stroke-related deaths, recurrent strokes, and nonstroke deaths. We evaluated 3-month mRS and death/disability at 1 and 5 years in a population-based cohort study.

METHODS AND RESULTS: In 3-month survivors of ischemic stroke (Oxford Vascular Study; 2002-2014), we related 3-month mRS to disability (defined as mRS >2) at 1 and 5 years and/or death rates (age/sex adjusted). Accrual of disability and index-stroke-related and nonstroke deaths in each poststroke year was categorized according to 3-month mRS. Among 1606 patients with acute ischemic stroke, 181 died within 3 months, but 126 index-stroke-related deaths and 320 other deaths occurred during the subsequent 4866 patient-years of follow-up up to 5 years. Although 69/126 (54.8%) post-3-month index-stroke-related deaths occurred after 1 year, mRS>2 at 1 year strongly predicted these deaths (adjusted hazard ratio=21.94, 95%CI 7.88-61.09, P<0.0001). Consequently, a 3-month mRS >2 was a strong independent predictor of death at both 1 year (adjusted hazard ratio=6.67, 95%CI 4.16-10.69, P<0.0001) and 5 years (adjusted hazard ratio=2.93, 95%CI 2.38-3.60, P<0.0001). Although mRS improved by ≥1 point from 3 months to 1 year in 317/1266 (25.0%) patients with 3-month mRS ≥1, improvement in mRS after 1 year was limited (improvement by ≥1 point: 91/858 [10.6%]; improvement to mRS ≤2: 13/353 [3.7%]).

CONCLUSIONS: Our results reaffirm use of the 3-month mRS outcome in stroke trials. Although later recovery does occur, extending follow-up to 1 year would capture most long-term stroke-related disability. However, administrative mortality follow-up beyond 1 year has the potential to demonstrate translation of early disability gains into additional reductions in long-term mortality without much erosion by non-stroke-related deaths.

Authors: Ganesh, A; Luengo-Fernandez, R; Wharton, R; Gutnikov, S; Silver, L

• Publication status: Published
• Peer review status: Peer reviewed
• Publisher: Wiley
• Journal: Journal of the American Heart Association
• Volume: 6
• Issue: 6
• Pages: e005788
• Publication date: 2017-06-11
• Acceptance date: 2017-04-10
• DOI: 10.1161/JAHA.117.005788
• ISSN: 2047-9980
• Language: English
• Keywords: longitudinal cohort study; cerebrovascular disease/stroke; stroke recovery; clinical trial design; health economics