Perceived changes and minimum clinically important difference of the Neurological Fatigue Index for multiple sclerosis (NFI-MS)

Abstract

The determination of the minimum clinically important difference (MCID) is an important aspect of scale development. The Neurological Fatigue Index for multiple sclerosis (NFI-MS) was administered before and after expected change or stability in fatigue in 208 multiple sclerosis (MS) patients. The overall change scores of the NFI-MS accorded with perceived direction of change; importantly, no change was seen when none was perceived. Using the interval level NFI-MS scores, the largest MCID equated to 2.49 points on the Summary scale, 2.36 points on the Physical scale, 0.84 points on the Cognitive scale, 0.97 on the Diurnal Sleep scale and 1.95 on the Nocturnal Sleep scale. Our conclusion is that the NFI-MS responds as expected to changes in fatigue and has desirably small MCID scores.

Keywords

fatigue outcome measurement Rasch analysis

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References

Mills

Young

Pallant

. Development of a patient reported outcome scale for fatigue in multiple sclerosis: The Neurological Fatigue Index (NFI). Health Qual Life Outcomes 2010; 8: 22.

Chuang-Stein

Kirby

Hirsch

. The role of the minimum clinically important difference and its impact on designing a trial. Pharm Stat 10: 250–256.

King

A point of minimal important difference (MID): a critique of terminology and methods. Expert Rev Pharmacoecon Outcomes Res 11: 171–184.

Revicki

Cella

Hays

. Responsiveness and minimal important differences for patient reported outcomes. Health Qual Life Outcomes 2006; 4: 70.

Shikiar

Willian

Okun

. The validity and responsiveness of three quality of life measures in the assessment of psoriasis patients: results of a phase II study. Health Qual Life Outcomes 2006; 4: 71.

Kurtzke

Rating neurologic impairment in multiple sclerosis: an expanded disability status scale (EDSS). Neurology 1983; 33: 1444–1452.