Intra-and inter-observer reliability of nailfold videocapillaroscopy — A possible outcome measure for systemic sclerosis-related microangiopathy

Graham Dinsdale, Tonia Moore, Neil O'Leary, Philip Tresadern, Michael Berks, Christopher Roberts, Joanne Manning, J. Allen, Marina E. Anderson, Maurizio Cutolo, Roger Hesselstrand, Kevin Howell, Carmen Pizzorni, Vanessa Smith, Alberto Sulli, Marie Wildt, Christopher Taylor, Andrea Murray, Ariane L Herrick

Research output: Contribution to journalArticle

12 Citations (Scopus)

Abstract

Objectives
Our aim was to assess the reliability of nailfold capillary assessment in terms of image evaluability, image severity grade (‘normal’, ‘early’, ‘active’, ‘late’), capillary density, capillary (apex) width, and presence of giant capillaries, and also to gain further insight into differences in these parameters between patients with systemic sclerosis (SSc), patients with primary Raynaud's phenomenon (PRP) and healthy control subjects.

Methods
Videocapillaroscopy images (magnification 300 ×) were acquired from all 10 digits from 173 participants: 101 patients with SSc, 22 with PRP and 50 healthy controls. Ten capillaroscopy experts from 7 European centres evaluated the images. Custom image mark-up software allowed extraction of the following outcome measures: overall grade (‘normal’, ‘early’, ‘active’, ‘late’, ‘non-specific’, or ‘ungradeable’), capillary density (vessels/mm), mean vessel apical width, and presence of giant capillaries.

Results
Observers analysed a median of 129 images each. Evaluability (i.e. the availability of measures) varied across outcome measures (e.g. 73.0% for density and 46.2% for overall grade in patients with SSc). Intra-observer reliability for evaluability was consistently higher than inter- (e.g. for density, intra-class correlation coefficient [ICC] was 0.71 within and 0.14 between observers). Conditional on evaluability, both intra- and inter-observer reliability were high for grade (ICC 0.93 and 0.78 respectively), density (0.91 and 0.64) and width (0.91 and 0.85).

Conclusions
Evaluability is one of the major challenges in assessing nailfold capillaries. However, when images are evaluable, the high intra- and inter-reliabilities suggest that overall image grade, capillary density and apex width have potential as outcome measures in longitudinal studies.

Original languageEnglish
Pages (from-to)1-6
Number of pages6
JournalMicrovascular Research
Volume112
Early online date2 Feb 2017
DOIs
Publication statusPublished - Jul 2017
Externally publishedYes

Keywords

  • Systemic sclerosis
  • Nailfold videocapillaroscopy
  • Reliability
  • Capillaroscopic patterns
  • Raynaud's phenomenon

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