Systematic literature review and validity evaluation of the Expanded Disability Status Scale (EDSS) and the Multiple Sclerosis Functional Composite (MSFC) in patients with multiple sclerosis

Abstract

BackgroundThere are a number of instruments that describe severity and progression of multiple sclerosis and they are increasingly used as endpoints to assess the effectiveness of therapeutic interventions. We examined to what extent the psychometric properties of two accepted instruments – EDSS and MSFC – meet methodological standards and the value they have in clinical trials.MethodsWe conducted a systematic literature search in relevant databases [MEDLINE (PubMed), ISI Web of Science, EMBASE, PsycINFO & PSYNDEX, CINAHL] yielding 3,860 results. Relevant full-text publications were identified using abstract and then full-text reviews, and the literature was reviewed.ResultsFor evaluation of psychometric properties (validity, reliability, sensitivity of change) of EDSS and MSFC, 120 relevant full-text publications were identified, 54 of them assessed the EDSS, 26 the MSFC and 40 included both instruments. The EDSS has some documented weaknesses in reliability and sensitivity to change. The main limitations of the MSFC are learning effects and the z-scores method used to calculate the total score. However, the methodological criterion of validity applies sufficiently for both instruments.For use in clinical studies, we found the EDSS to be preferred as a primary and secondary outcome measure in recent studies (50 EDSS, 9 MSFC).ConclusionsRecognizing their strengths and weaknesses, both EDSS and MSFC are suitable to detect the effectiveness of clinical interventions and to monitor disease progression. Almost all publications identify the EDSS as the most widely used tool to measure disease outcomes in clinical trials. Despite some limitations, both instruments are accepted as endpoints and neither are discussed as surrogate parameters in identified publications. A great advantage of the EDSS is its international acceptance (e.g. by EMA) as a primary endpoint in clinical trials and its broad use in trials, enabling cross-study comparisons.

Current Issues of Etiopathogenesis, Clinical Picture, Diagnosis and Treatment of Multiple Sclerosis (Literature Review and Own Data)

“…РС не считают наследст-венным заболеванием. Генетическая пред-расположенность к РС, вероятно, связана с сочетанием у данного индивидуума не-скольких генов, обусловливающих нару-шения, прежде всего, в системе иммуноре-гуляции, что может предопределять не только возможность возникновения забо-левания, но и отражаться на особенностях его клинического течения [7,[20][21][22].…”

“…Для оценки неврологических проявлений чаще всего используется шкала состояния функцио-нальных систем (FSS) и расширенная шкала оценки инвалидизации (Expanded Disability Status Scale, EDSS) по J. Kurtzke. Шкала FSS подразумевает оценку в баллах от 0 до 6 по степени выраженности симптомов поражения различных систем, а шкала EDSS оценивает общую степень инвалид-ности в баллах от 0 до 10 [3,21,27].…”

“…РБН может быть, как односторонним, так и двусто-ронним. Изолированный РБН чаще встре-чается у женщин, чем у мужчин [21,28].…”

Comparison of the Kurtkze Expanded Disability Status Scale and the Functional Independence Measure: Measures of Multiple Sclerosis Related Disability

“…The EDSS is scored in increments of 0.5 points, and includes the scores of eight FS items: pyramidal, cerebellar, brain-stem, sensory, bowel and bladder, visual, mental and other functions (Appendix 1A and 1B). The EDSS has a bi-modal distribution in valid cross-sectional studies [6], and has a fair to substantial inter-rater reliability (κ=0.32 to 0.76) [7,8], with a 2 point change considered a reliable indicator of the patient's response to treatment [9]. Though EDSS is an impairment scale it has been commonly used as an outcome measure of MS-related disability [10,11].…”

“…Tests results are converted to z-score [13]. Its advantages include it being reliable (intra-rater intra-class correlation (ICC)=0.98, inter-rater ICC=0.96) [8,14,15], efficient, and reproducible [16]. However, it is a cumbersome scale to use in everyday clinical practice for the following reasons: i) complains such as dysarthria affects PASAT performance; ii) visual disturbance affects 9HPT; iii) there is no measure for involved vision; iv) calculation and clinical interpretation of Z-scores are difficult; and v) there is a practice effect with tests repetition especially for the PASAT.…”