Improving assessment in small fiber neuropathy

Brigitte A. Brouwer, Mayienne Bakkers, Janneke G. J. Hoeijmakers, Catharina G. Faber, Ingemar S. J. Merkies*

*Corresponding author for this work

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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(C)), 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(C)) 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(C) scale was constructed that fulfilled all Rasch requirements, demonstrating acceptable reliability and validity scores. The 13-item SFN-SIQ(C) was successfully transformed to an interval Rasch-built measure fulfilling model's requirements. In conclusion, the 32-item SFN-RODS(C) is a disease-specific interval measure suitable for detecting activity limitations and participation restrictions in patients with SFN. The 13-item SFN-SIQ(C) was transformed through Rasch to an interval measure. The use of these scales is recommended in future clinical interventional trials involving patients with SFN.
Original languageEnglish
Pages (from-to)333-340
JournalJournal of the Peripheral Nervous System
Issue number3
Publication statusPublished - Sept 2015


  • outcome research
  • peripheral neuropathy
  • Rasch-built overall disability scale
  • small fiber neuropathy

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