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



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.



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).



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.
Division of Musculoskeletal & Dermatological Sciences, University of Manchester, Manchester Academic Health Science Centre, Manchester, UK. Electronic address: graham.dinsdale@manchester.ac.uk.
Graham
G
Dinsdale
Salford Royal Hospital NHS Foundation Trust, Salford, UK.
Tonia
T
Moore
Centre for Biostatistics, Division of Population Health, Health Services Research & Primary Care, University of Manchester, Manchester, UK.
Neil
N
O'Leary
Centre for Imaging Sciences, Division of Informatics, Imaging & Data Sciences, University of Manchester, Manchester, UK.
Philip
P
Tresadern
Centre for Imaging Sciences, Division of Informatics, Imaging & Data Sciences, University of Manchester, Manchester, UK.
Michael
M
Berks
Centre for Biostatistics, Division of Population Health, Health Services Research & Primary Care, University of Manchester, Manchester, UK.
Christopher
C
Roberts
Salford Royal Hospital NHS Foundation Trust, Salford, UK.
Joanne
J
Manning
Microvascular Diagnostics, Northern Medical Physics and Clinical Engineering, Freeman Hospital, Newcastle upon Tyne, UK.
John
J
Allen
Institute of Ageing and Chronic Disease, University of Liverpool, Liverpool, UK.
Marina
M
Anderson
Research Laboratory and Academic Division of Clinical Rheumatology, Dept. Internal Medicine, University of Genova, Italy.
Maurizio
M
Cutolo
Department of Clinical Sciences, Section of Rheumatology, Lund University, Lund, Sweden.
Roger
R
Hesselstrand
Institute of Immunity and Transplantation, University College London, Royal Free Campus, London, UK.
Kevin
K
Howell
Research Laboratory and Academic Division of Clinical Rheumatology, Dept. Internal Medicine, University of Genova, Italy.
Carmen
C
Pizzorni
Department of Rheumatology, Ghent University Hospital, Faculty of Internal Medicine, Ghent University, Ghent, Belgium.
Vanessa
V
Smith
Research Laboratory and Academic Division of Clinical Rheumatology, Dept. Internal Medicine, University of Genova, Italy.
Alberto
A
Sulli
Department of Clinical Sciences, Section of Rheumatology, Lund University, Lund, Sweden.
Marie
M
Wildt
Centre for Imaging Sciences, Division of Informatics, Imaging & Data Sciences, University of Manchester, Manchester, UK.
Christopher
C
Taylor
Division of Musculoskeletal & Dermatological Sciences, University of Manchester, Manchester Academic Health Science Centre, Manchester, UK.
Andrea
A
Murray
Division of Musculoskeletal & Dermatological Sciences, University of Manchester, Manchester Academic Health Science Centre, Manchester, UK; NIHR Manchester Musculoskeletal Biomedical Research Unit, Central Manchester NHS Foundation Trust, Manchester Academic Health Science Centre, Manchester, UK.
Ariane L
AL
Herrick
D000328:Adult; D000368:Aged; D002196:Capillaries / Q000473:pathology*; D016022:Case-Control Studies; D005060:Europe; D005260:Female; D006801:Humans; D007090:Image Interpretation, Computer-Assisted; D008297:Male; D020678:Microscopic Angioscopy; D008875:Middle Aged; D009262:Nails / Q000098:blood supply*; D015588:Observer Variation; D011237:Predictive Value of Tests; D015203:Reproducibility of Results; D012595:Scleroderma, Systemic / Q000150:complications* / Q000175:diagnosis; D012720:Severity of Illness Index; D012984:Software; D014652:Vascular Diseases / Q000175:diagnosis* / Q000209:etiology / Q000473:pathology; D055815:Young Adult
Capillaroscopic patterns; Nailfold videocapillaroscopy; Raynaud's phenomenon; Reliability; Systemic sclerosis