Assessment of functional outcome in a national quality register for acute stroke: can simple self-reported items be transformed into the modified Rankin Scale?

Abstract

Background and purpose: To enable self-reporting of functional outcome in quality registers, the corresponding questions have to be easy to interpret. In scientific research, the modified Rankin Scale (mRS) is a standard assessment method. Such methods, with an outsider observer, are not feasible to use in quality registers. For several aspects, eg, comparisons between outcome in clinical studies and observational studies, we determined to see whether the functional outcome, as assessed in a quality register, can be transformed into mRS grades.

Methods: The agreement between self-reported functional outcome (including dependency, living situation, mobility, dressing and toileting) and mRS were analyzed using 555 stroke patients registered in Riks-Stroke, the Swedish quality register for acute stroke, during a 5-month period in 4 hospitals. The self-reported outcome and the mRS grades were concurrently assessed by a telephone interview performed by an experienced nurse 3 months after stroke.

Results: A translation using 5 of the questions from Riks-Stroke classified 76% of the patients to the correct mRS grade. The correlation between Riks-Stroke and mRS was 0.821 and Cohen's kappa (weighted) was 0.853.

Conclusions: The study shows that self-reported functional outcome can be transformed into mRS grades with a high precision, making the translation useful for future comparative purposes in stroke outcome studies.