Determining the modified Rankin score after stroke by postal and telephone questionnaires

The modified Rankin Scale (mRS) is the most common outcome measure in large randomized controlled trials in stroke. We tested 2 postal mRS questionnaires and a telephone questionnaire to determine completion rates and intermodality agreement.

We sent postal questionnaires containing 2 versions of the mRS to surviving stroke patients. One version, tick box, involved the patient/proxy ticking 1 of the 5 descriptions equating to mRS scores; the other, the simplified modified Rankin questionnaire (smRSq), included 5 questions with yes/no responses from which the mRS is derived. We performed a semistructured telephone interview to consenting respondents, blinded to postal responses, to assign an mRS. We compared the mRS obtained by these different methods.

We sent questionnaires to 343 of 356 surviving patients (96%) and received 225 responses (66%). The mRS could not be derived in 27 respondents (12%) and 10 respondents (4%) on the tick box and smRSq, respectively (difference in proportion, 8% [95% CI, 3-13]. One hundred three of 190 respondents (54%) to the postal questionnaire agreed on the tick box versus smRSq version (κ=0.44 [0.38, 0.50]). Agreements between the tick box versus telephone and smRSq versus telephone were 57% (ie, 87/152, κ=0.47 [0.40, 0.55], and 64% (ie, 104/161, κ=0.55 [0.47, 0.62], respectively.

In large studies where face-to-face assessment of mRS is impractical, a postal smRSq with telephone follow-up to nonresponders will achieve higher levels of follow-up than will the tick box version and also good levels of intermodality agreement with least risk of bias.