Prestroke Modified Rankin Stroke Scale Has Moderate Interobserver Reliability and Validity in an Acute Stroke Setting

Abstract

Background and Purpose-The modified Rankin Scale (mRS) is the recommended functional outcome assessment in stroke trials. Utility of mRS may be limited by interobserver variability. Prestroke function, described using mRS, is often used as trial entry criterion. We assessed the reliability and validity of prestroke mRS in acute stroke. Methods-We present two complementary analyses of the properties of prestroke mRS: (1) Paired interviewers (trained in mRS) performed independently a blinded assessment of mRS and prestroke mRS. Interobserver variability was described using percentage agreement and weighted (kw) κ statistics with 95% confidence interval (95% CI). Validity was assessed by comparing prestroke mRS with other markers of function (comorbidity; medication count; need for carers). (2) We further assessed validity using a larger retrospective dataset. We compared prestroke mRS with Charlson comorbidity index (CCI) and the Rockwood frailty index. Rank correlation coefficient or Fisher exact test were used as appropriate. Results-Paired

Response to Letter Regarding Article, “Prestroke Modified Rankin Stroke Scale Has Moderate Interobserver Reliability and Validity in an Acute Stroke Setting”

“…1 We agree with all the points made in their letter, and it is reassuring that other centers are also giving some consideration to the clinimetric properties of mRS when used to describe functional ability prestroke.…”

Intravenous Thrombolysis in Patients Dependent on the Daily Help of Others Before Stroke

“…(4) The assessment of the prestroke mRS is challenging, and its reliability is limited. 19 Furthermore, the raters of the mRS at 3 months were not blinded to the prestroke mRS, which may have had influenced their rating. (5) The meaning of the causes of preexisting dependency could not be addressed sufficiently because such data were only available for a subgroup of patients.…”

Cognitive and Mood Assessment Tools for Use in Stroke

“…Traditionally the assessment of prestroke function has used the modified Rankin Scale (mRS). 20 Newer assessments designed to describe physical and cognitive frailty may also provide useful information.…”