Variability of the Modified Rankin Scale Score Between Day 90 and 1 Year After Ischemic Stroke.

Abstract

Studies indicate that the functional outcome evolves in the year after ischemic stroke onset. However, the traditional outcome measure in stroke trials is the modified Rankin Scale (mRS) at 90 days from onset. To determine mRS fluctuations in the first year after stroke, we examined data from 3 major stroke trials. In a secondary analysis, we evaluated intrapatient mRS between 90 days and 1 year from stroke onset, the mRS shift (∆mRS = 1 year-day 90), and the trials' primary outcome at day 90 and 1 year. We included 624 patients from the National Institute of Neurological Disorders and Stroke rt-PA Stroke Study, 587 from Albumin Treatment for Acute Ischaemic Stroke, and 611 from Interventional Management of Stroke III, for which the proportion of patients with a ∆mRS change between day 90 and 1 year was 36.5%, 41.7%, and 36.0%. However, the trials' primary outcomes did not differ at 1 year vs 90 days. Similar findings were seen in a second cohort where we pooled the trials and excluded patients with recurrent stroke or death during the follow-up. In those 1,314 patients, 544 (41.4%) had a ∆mRS change, of which 379 (28.9%) had improvement and 165 (12.5%) had worsening, apart from death. We describe the patient-level spectrum of mRS change from day 90 to 1 year after ischemic stroke in 3 high-quality randomized trials. The patient-level shifts consisted of a sufficiently counterbalanced number of mRS improvements and declines, which masked clinical evolution occurring in over one-third of patients. These results may have important implications, both for clinical trial design and outcome adjudication in stroke research and duration of rehabilitative therapy.