title: Improving assessment in small fiber neuropathy.
abstract: Interval measures at the impairment level addressing symptoms and at the activity/participation level addressing daily and social restrictions have not been developed for small fiber neuropathy (SFN). We developed an SFN-specific Rasch-built overall disability scale (SFN-RODS©), an activity/participation scale at the interval level. A preliminary SFN-RODS containing 146 activity/participation items was assessed twice (reliability studies) in 238 patients with SFN. The ordinal-based 13-item SFN-symptoms inventory questionnaire (SFN-SIQ©) and pain-visual-analogue-scale were also assessed (validity studies). The pre-SFN-RODS and SFN-SIQ data were subjected to the Rasch analyses. The pre-SFN-RODS did not meet Rasch model expectations. Based on requirements, such as misfit statistics, differential item functioning, and local dependency, items were systematically removed and model fit improved. Finally, a 32-item SFN-RODS© scale was constructed that fulfilled all Rasch requirements, demonstrating acceptable reliability and validity scores. The 13-item SFN-SIQ© was successfully transformed to an interval Rasch-built measure fulfilling model's requirements. In conclusion, the 32-item SFN-RODS© is a disease-specific interval measure suitable for detecting activity limitations and participation restrictions in patients with SFN. The 13-item SFN-SIQ© was transformed through Rasch to an interval measure. The use of these scales is recommended in future clinical interventional trials involving patients with SFN.
authors.affiliation: Department of Anesthesiology and Pain Management, Maastricht University Medical Center, PO Box 5800, 6202 AZ, Maastricht, The Netherlands.
authors.forename: Brigitte A
authors.initials: BA
authors.lastname: Brouwer
authors.affiliation: Department of Neurology, Maastricht University Medical Center, PO Box 5800, 6202 AZ, Maastricht, The Netherlands.
authors.forename: Mayienne
authors.initials: M
authors.lastname: Bakkers
authors.affiliation: Department of Neurology, Maastricht University Medical Center, PO Box 5800, 6202 AZ, Maastricht, The Netherlands.
authors.forename: Janneke G J
authors.initials: JG
authors.lastname: Hoeijmakers
authors.affiliation: Department of Neurology, Maastricht University Medical Center, PO Box 5800, 6202 AZ, Maastricht, The Netherlands.
authors.forename: Catharina G
authors.initials: CG
authors.lastname: Faber
authors.affiliation: Department of Neurology, Maastricht University Medical Center, PO Box 5800, 6202 AZ, Maastricht, The Netherlands.|Department of Neurology, Spaarne Hospital, Spaarnepoort 1, 2134 TM, Hoofddorp, The Netherlands.
authors.forename: Ingemar S J
authors.initials: IS
authors.lastname: Merkies
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D015331:Cohort Studies; D006233:Persons with Disabilities; D004916:Erythromelalgia / Q000175:diagnosis* / Q000503:physiopathology*; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D017063:Outcome Assessment, Health Care / Q000379:methods*; D011594:Psychometrics; D015203:Reproducibility of Results; D012720:Severity of Illness Index; D011795:Surveys and Questionnaires; D055815:Young Adult
keywords: Rasch-built overall disability scale; outcome research; peripheral neuropathy; small fiber neuropathy