{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,7,21]],"date-time":"2026-07-21T23:10:51Z","timestamp":1784675451916,"version":"3.55.0"},"reference-count":48,"publisher":"Wiley","issue":"2","license":[{"start":{"date-parts":[[2017,6,27]],"date-time":"2017-06-27T00:00:00Z","timestamp":1498521600000},"content-version":"vor","delay-in-days":0,"URL":"http:\/\/onlinelibrary.wiley.com\/termsAndConditions#vor"}],"funder":[{"name":"Neurological Disability Fund"},{"name":"Research Department of the Walton Centre NHS Foundation Trust"}],"content-domain":{"domain":["onlinelibrary.wiley.com"],"crossmark-restriction":true},"short-container-title":["PM&amp;R"],"published-print":{"date-parts":[[2018,2]]},"abstract":"<jats:title>Abstract<\/jats:title><jats:sec><jats:title>Background<\/jats:title><jats:p>Fatigue in post\u2010polio syndrome (PPS) has been shown to affect quality of life adversely. There is currently no disease\u2010specific measure of fatigue for PPS.<\/jats:p><\/jats:sec><jats:sec><jats:title>Objective<\/jats:title><jats:p>To develop a scale to measure fatigue in PPS that meets rigorous psychometric standards.<\/jats:p><\/jats:sec><jats:sec><jats:title>Design<\/jats:title><jats:p>Qualitative followed by validation and test\u2010retest studies.<\/jats:p><\/jats:sec><jats:sec><jats:title>Setting<\/jats:title><jats:p>Polio clinic followed by national questionnaire studies.<\/jats:p><\/jats:sec><jats:sec><jats:title>Participants<\/jats:title><jats:p>A total of 45 participants from polio clinic for qualitative; 319 participants from clinic or self\u2010referral for validation study, of whom 87 completed the retest questionnaire.<\/jats:p><\/jats:sec><jats:sec><jats:title>Methods<\/jats:title><jats:p>Draft questionnaire items on PPS fatigue were derived from transcripts of qualitative interviews. After cognitive debriefing, the draft measure was administered by mail along with comparator questionnaires to a new sample.<\/jats:p><\/jats:sec><jats:sec><jats:title>Main Outcome Measurements<\/jats:title><jats:p>Draft PPS fatigue measure, Fatigue Severity Scale, and visual analog scale for fatigue.<\/jats:p><\/jats:sec><jats:sec><jats:title>Results<\/jats:title><jats:p>Analysis of 271 of 319 (85%) questionnaires identified a 2\u2010factor solution (RMSEA 0.058). For the physical subscale, a 20\u2010item scale showed good fit (\u03c7<jats:sup>2<\/jats:sup> <jats:italic>P<\/jats:italic> = .189), strict unidimensionality (<jats:italic>t<\/jats:italic>\u2010test 5.17%), and reliability 0.91. For the cognitive subscale, a 7\u2010item scale showed excellent fit (\u03c7<jats:sup>2<\/jats:sup> <jats:italic>P<\/jats:italic> = .917), strict unidimensionality (<jats:italic>t<\/jats:italic>\u2010test 5.2%), and reliability 0.89. Evidence of a \u201cdifficulty factor\u201d emerged also supporting a total score that showed good fit (\u03c7<jats:sup>2<\/jats:sup> <jats:italic>P<\/jats:italic> = .151), strict unidimensionality (<jats:italic>t<\/jats:italic>\u2010test 0.4%), and reliability consistent with group use at 0.73. Test\u2010retest correlations for all scales were greater than 0.85. Standard error of measurement on metric ranges was 5.4 for total, 2.9 for physical, and 1.69 for cognitive domains. With the latent estimate of the total score transformed to a 0\u2010100 scale, the mean score was 49.5 (SD 6.9). Spearman correlations with the Fatigue Severity Scale and visual analog scale were 0.60 and 0.55, respectively.<\/jats:p><\/jats:sec><jats:sec><jats:title>Conclusions<\/jats:title><jats:p>A patient\u2010derived Neurological Fatigue Index for PPS, with physical and cognitive subscales and a total score, has demonstrated good reliability, appropriate concurrent validity, and satisfies the Rasch measurement model. A raw\u2010score to interval scale transformation is available for parametric applications and the calculation of change scores.<\/jats:p><\/jats:sec><jats:sec><jats:title>Level of Evidence<\/jats:title><jats:p>III<\/jats:p><\/jats:sec>","DOI":"10.1016\/j.pmrj.2017.06.014","type":"journal-article","created":{"date-parts":[[2017,6,27]],"date-time":"2017-06-27T06:17:43Z","timestamp":1498544263000},"page":"129-136","update-policy":"https:\/\/doi.org\/10.1002\/crossmark_policy","source":"Crossref","is-referenced-by-count":2,"title":["Measuring Physical and Cognitive Fatigue in People With Post\u2010Polio Syndrome: Development of the Neurological Fatigue Index for Post\u2010Polio Syndrome (NFI\u2010PP)"],"prefix":"10.1002","volume":"10","author":[{"given":"Carolyn A.","family":"Young","sequence":"first","affiliation":[],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Samantha M.","family":"Wong","sequence":"additional","affiliation":[],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Anne\u2010Marie C.","family":"Quincey","sequence":"additional","affiliation":[],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Alan","family":"Tennant","sequence":"additional","affiliation":[],"role":[{"vocabulary":"crossref","role":"author"}]}],"member":"311","published-online":{"date-parts":[[2017,6,27]]},"reference":[{"key":"e_1_2_7_2_2","volume-title":"Polio Survivors in the U.S., 1915\u20102000. 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