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

Research output: Contribution to journalArticle

  • External authors:
  • Tonia Moore
  • Neil O'Leary
  • Philip Tresadern
  • Christopher Roberts
  • Joanne Manning
  • John Allen
  • Marina Anderson
  • Maurizio Cutolo
  • Roger Hesselstrand
  • Kevin Howell
  • Carmen Pizzorni
  • Vanessa Smith
  • Alberto Sulli
  • Marie Wildt

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.

Bibliographical metadata

Original languageEnglish
Pages (from-to)1-6
Number of pages6
JournalMicrovascular Research
Volume112
Early online date2 Feb 2017
DOIs
StatePublished - 2017