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Published on: June 12, 2019
Prestroke modified rankin stroke scale has moderate interobserver reliability and validity in an acute stroke setting
Patrica Fearon1, Kate S McArthur, Kevin Garrity
1Institute of Cardiovascular and Medical Sciences, Undergraduate Medical School, University of Glasgow, and Department of Academic Geriatric Medicine, Walton Bldg, Glasgow Royal Infirmary, Glasgow, UK G4 0SF.
Stroke
|November 15, 2012
Summary
Prestroke modified Rankin Scale (mRS) assessment in stroke trials shows limited reliability and validity. Relying solely on mRS may bias trial participant selection and outcomes.
Area of Science:
- Neurology
- Clinical Trials
- Biostatistics
Background:
- The modified Rankin Scale (mRS) is standard for assessing functional outcomes in stroke trials.
- Interobserver variability can limit the utility of the mRS.
- Prestroke function, assessed by mRS, is frequently used as a trial entry criterion.
Purpose of the Study:
- To evaluate the reliability and validity of prestroke mRS in acute stroke patients.
- To determine if prestroke mRS is a reliable measure for trial eligibility.
Main Methods:
- Two analyses were conducted: paired interviewer assessments and a retrospective dataset analysis.
- Interobserver variability was quantified using percentage agreement and weighted kappa statistics.
- Validity was assessed by correlating prestroke mRS with comorbidity indices, age, medication count, and need for carers.
Main Results:
- Prestroke mRS showed moderate reliability (70% agreement, kw=0.70), comparable to standard mRS (56% agreement, kw=0.55).
- Strong correlation was found between prestroke mRS and frailty index (Spearman Rho=0.82).
- Weak correlations were observed with Charlson Comorbidity Index (0.50) and age (0.45), with no association with need for carers.
Conclusions:
- Prestroke mRS demonstrates limited interobserver reliability, though comparable to standard mRS.
- The poor correlation with some functional markers indicates limited validity for prestroke mRS.
- Using mRS alone for prestroke function assessment may be suboptimal and could introduce bias in stroke trial participant selection.
