University of Hertfordshire

From the same journal

From the same journal

By the same authors

Revised Hammersmith Scale for Spinal Muscular Atrophy: A SMA specific clinical outcome assessment tool

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  • Mariacristina Scoto
  • Anna Mayhew
  • Marion Main
  • Elena S Mazzone
  • Jacqueline Montes
  • Roberto de Sanctis
  • Sally Dunaway Young
  • Rachel Salazar
  • Allan M Glanzman
  • Amy Pasternak
  • Janet Quigley
  • Elizabeth Mirek
  • Tina Duong
  • Richard Gee
  • Matthew Civitello
  • Gihan Tennekoon
  • Marika Pane
  • Maria Carmela Pera
  • Kate Bushby
  • John Day
  • Basil T Darras
  • Darryl De Vivo
  • Richard Finkel
  • Eugenio Mercuri
  • Francesco Muntoni
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Original languageEnglish
Article numbere0172346
Number of pages19
JournalPLoS ONE
Volume12
Issue2
DOIs
Publication statusPublished - 21 Feb 2017

Abstract

Recent translational research developments in Spinal Muscular Atrophy (SMA), outcome measure design and demands from regulatory authorities require that clinical outcome assessments are 'fit for purpose'. An international collaboration (SMA REACH UK, Italian SMA Network and PNCRN USA) undertook an iterative process to address discontinuity in the recorded performance of the Hammersmith Functional Motor Scale Expanded and developed a revised functional scale using Rasch analysis, traditional psychometric techniques and the application of clinical sensibility via expert panels. Specifically, we intended to develop a psychometrically and clinically robust functional clinician rated outcome measure to assess physical abilities in weak SMA type 2 through to strong ambulant SMA type 3 patients. The final scale, the Revised Hammersmith Scale (RHS) for SMA, consisting of 36 items and two timed tests, was piloted in 138 patients with type 2 and 3 SMA in an observational cross-sectional multi-centre study across the three national networks. Rasch analysis demonstrated very good fit of all 36 items to the construct of motor performance, good reliability with a high Person Separation Index PSI 0.98, logical and hierarchical scoring in 27/36 items and excellent targeting with minimal ceiling. The RHS differentiated between clinically different groups: SMA type, World Health Organisation (WHO) categories, ambulatory status, and SMA type combined with ambulatory status (all p < 0.001). Construct and concurrent validity was also confirmed with a strong significant positive correlation with the WHO motor milestones rs = 0.860, p < 0.001. We conclude that the RHS is a psychometrically sound and versatile clinical outcome assessment to test the broad range of physical abilities of patients with type 2 and 3 SMA. Further longitudinal testing of the scale with regards change in scores over 6 and 12 months are required prior to its adoption in clinical trials.

Notes

This is an open access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.

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