Optimizing cutoff scores for the Barthel index and the modified Rankin scale for defining outcome in acute stroke trials.
OBJECTIVE
There is little agreement on how to assess outcome in acute stroke trials. Cutoff scores for the Barthel Index (BI) and modified Rankin Scale (mRS) are frequently arbitrarily chosen to dichotomize favorable and unfavorable outcome. We investigated sensitivity and specificity of BI cutoff scores in relation to the mRS to obtain the optimal corresponding BI and mRS scores.


METHODS
BI and mRS scores were collected from 1034 ischemic stroke patients. Sensitivity and specificity were calculated for BI cutoff scores from 45 to 100 in mRS score 1, 2, and 3 and were plotted in receiver operator characteristic (ROC) curves.


RESULTS
The cutoff scores for the BI with the highest sum of sensitivity and specificity were 95 (sensitivity 85.6%; specificity 91.7%), 90 (sensitivity 90.7%; specificity 88.1%), and 75 (sensitivity 95.7%; specificity, 88.5%) for, respectively, mRS 1, 2, and 3. The area under the ROC curve was 0.933 in mRS 1, 0.960 in mRS 2, and 0.979 in mRS 3.


CONCLUSIONS
The optimal cutoff scores for the BI were 95 for mRS 1, 90 for mRS 2, and 75 for mRS 3. For future acute stroke trials that assess stroke outcome with the BI and mRS, we recommend the use of these BI cutoff score(s) with the corresponding mRS cutoff score(s), to ensure the use of consistent and uniform end points.
Uyttenboogaart
Maarten
M
Department of Neurology, University Medical Center Groningen, PO Box 30.001, 9700 RB Groningen, The Netherlands. m.uyttenboogaart@neuro.umcg.nl
Stewart
Roy E
RE
Vroomen
Patrick C A J
PC
De Keyser
Jacques
J
Luijckx
Gert-Jan
GJ
D000368:Aged; D002545:Brain Ischemia / Q000628:therapy; D002986:Clinical Trials as Topic / Q000379:methods*; D004185:Disability Evaluation; D023381:Endpoint Determination; D005260:Female; D006801:Humans; D007511:Ischemia / Q000628:therapy; D008297:Male; D008875:Middle Aged; D015233:Models, Statistical; D017063:Outcome Assessment, Health Care / Q000379:methods*; D012372:ROC Curve; D012107:Research Design; D012680:Sensitivity and Specificity; D020521:Stroke / Q000628:therapy*; D000071939:Stroke Rehabilitation; D016896:Treatment Outcome