Expanded Disability Status Scale Calculator for Handheld Personal Digital Assistant: Reliability Study

Through a standard neurological examination, the Expanded Disability Status Scale (EDSS) score is traditionally determined by a pen-and-paper method. The objectives of this study were to compare the interrater/method reliability of EDSS scores obtained through the pen-and-paper method with those obtained with the EDSS Calculator, evaluate test-retest reliability of the EDSS Calculator, and examine the validity of EDSS Calculator scores through correlation with the Ambulation Index (AI). During a single office visit, 62 subjects with multiple sclerosis (MS) from six study centers had disability levels evaluated by separate raters using the EDSS calculator and pen-and-paper methods in random order. Seven days later, subjects returned for reevaluation with the EDSS Calculator; AI was also evaluated. Mean EDSS scores for the sample were 3.5 ± 2.2 with the calculator and 3.4 ± 2.0 (range 0–8) with the traditional method. Interrater reliability between scores with the two methods was high (κ = 0.84; confidence interval [CI], 0.74–0.94). Test-retest reliability with the calculator was also high (κ = 0.93; CI, 0.86–0.996). Correlation between disability scores from the EDSS Calculator and AI was 0.73 (P <.001). Relative to the pen-and paper method, the EDSS Calculator was found to be highly reliable and provide valid results when measuring disability in MS patients.