Original Article
Defining Mild Stroke: Outcomes Analysis of Treated and Untreated Mild Stroke Patients

https://doi.org/10.1016/j.jstrokecerebrovasdis.2015.01.037Get rights and content

Background

Mild deficit is a relative contraindication to administration of intravenous recombinant tissue plasminogen activator (IV rtPA) for acute ischemic stroke. However, what constitutes “mild” deficit is vague. Prior studies showed patients with mild strokes have substantial disability rates at hospital discharge and at 90 days. We investigated whether the application of a new definition altered the rates of disability overall and assessed the effects of thrombolysis.

Methods

This analysis included all adult acute ischemic stroke patients from a prospective registry of consecutive patients (University of California San Diego Specialized Programs of Translational Research in Acute Stroke (SPOTRIAS) database, 2003-2014) with 90-day modified Rankin Scale (mRS) score available who were defined as “mild” using either: National Institutes of Health Stroke Scale (NIHSS) 0-5 or a “Re-examining Acute Eligibility for Thrombolysis” (TREAT) Task Force definition (NIHSS 0-5 and nondisabling based on prespecified syndromes). Dichotomized 90-day mRS were compared between treated and untreated patients using the 2 definitions.

Results

Of 802 ischemic stroke patients with mRS scores available, 184 had baseline mRS (0) and met TREAT criteria; 45 (24.5%) were rtPA treated. Among the treated patients, 35.6% had 90-day mRS (2-6), versus 28.8% in the untreated group, a nonsignificant difference after adjusting for baseline NIHSS (P = .47). None of the 45 treated patients had symptomatic hemorrhage. Outcomes were similar using the simpler NIHSS 0-5 definition.

Conclusions

About one third of mild stroke patients were not functionally independent at 90 days, irrespective of treatment or mild definition applied, calling into question the treatment efficacy of IV rtPA for mild strokes and what constitutes an appropriate definition of “mild.” Randomized studies are necessary to determine rtPA treatment efficacy in mild stroke patients.

Section snippets

Methods

This analysis included review of all adult acute ischemic stroke patients from a prospective registry of consecutive stroke code patients (the University of California San Diego Specialized Programs of Translational Research in Acute Stroke (SPOTRIAS) database, 2003-2014) with 90-day modified Rankin Scale (mRS) score available who could be classified as “mild” by various definitions. Stroke codes are routinely called on patients presenting within 12 hours of onset of neurologic deficit.

Results

There were 802 acute ischemic stroke patients included in our database who had 90-day mRS scores available. These patients did not represent mimics or transient ischemic attacks; after analysis of the clinical course and imaging, multiple stroke practitioners determined them to be ischemic strokes. This consensus was reached at a weekly stroke team meeting during which all aspects of the case were presented. When analysis was limited to baseline mRS of 0 (analyses 1 and 2), we identified 276

Discussion

Using both definitions of mild stroke (either simply NIHSS 0-5 or the TREAT-derived definition) we were unable to convincingly show a difference in outcomes in treated versus untreated mild stroke patients. In addition, we did not show a difference in outcomes based on the definition used. Regardless of treatment being given, or which definition was used, 25%-30% of patients did not have good functional outcome at 90 days. This emphasizes the current equipoise for efficacy of intravenous rtPA

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B.C.M. was supported by an NIH grant: P50N5044148 (UCSD). The University of Cincinnati Department of Neurology iis paid for P.K.'s research efforts by Penumbra (THERAPY Trial Neuro PI), Genentech (PRISMS Trial PI), and Biogen (DSMB Member).

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