Arthritis & Rheumatism, Volume 62,
November 2010 Abstract Supplement

Abstracts of the American College of
Rheumatology/Association of Rheumatology Health Professionals
Annual Scientific Meeting
Atlanta, Georgia November 6-11, 2010.


High Reliability of Nailfold VideocapillaroscopyAn Outcome Measure for Systemic Sclerosis-Related Microvsacular Disease?

Hofstee4,  Herman, Serne4,  Erik, Roberts2,  Chris, Hesselstrand1,  Roger, Scheja1,  Agneta, Moore3,  Tonia, Wildt1,  Marie

Lund University, Sweden
The University of Manchester, United Kingdom
The University of Manchester, United Kingdom
VU University Medical Center, Amsterdam, The Netherlands

Background:

Systemic sclerosis (SSc)-related structural microvascular abnormalities can be directly visualised using the non-invasive technique of nailfold capillaroscopy. Computerised techniques combined with high magnification videocapillaroscopy bring the potential of capillaroscopy being not only a diagnostic tool but also an outcome measure in longitudinal studies of SSc-related microvascular disease, including studies of treatment response. Good reliability is a necessary prerequisite for a test to be a valid clinical or research tool. The aim of our study was to investigate the inter- and intra-observer reliability of both qualitative and quantitative nailfold capillaroscopic parameters.

Methods:

Mosaic nailfold images were acquired from the non-dominant ring finger of 10 healthy controls, 10 patients with primary Raynaud's phenomenon, and 30 with SSc using a computerised videocapillaroscopy system (magnification 300x). Each image was assessed 'blindly' by 6 observers (2 from each of 3 centres from 3 different countries). Images were graded for both qualitative (including capillary architecture, avascularity, haemorrhages, and tortuous, ramified, bushy and bizarre loops) and quantitative parameters (including number of mega- and giant capillaries, capillary density, and capillary dimensions). Inter-and intra-rater reproducibility were assessed for (a) ordered categorical scores (qualitative and quantitative) using a weighted kappa co-efficient with quadratic weights and (b) quantitative measurements using intra-class correlations.

Results:

These are summarised in the table.

 Inter-observer reliabilityIntra-observer reliability
Weighted Kappa of ordered categories (95% CI)
Architecture0.72 (0.55, 0.82)0.75 (0.64, 0.83)
Avascularity0.61 (0.37, 0.75)0.74 (0.62, 0.82)
Haemorrhage0.56 (0.16, 0.79)0.73 (0.57, 0.86)
Tortuous0.39 (0.25, 0.50)0.68 (0.60, 0.76)
Ramified0.58 (0.30, 0.73)0.73 (0.59, 0.84)
Bushy0.73 (-0.02, 0.90)0.80 (0.58, 0.94)
Bizarre0.21 (0.00, 0.32)0.76 (0.55, 0.92)
Mega capillary0.76 (0.64, 0.84)0.87 (0.82, 0.91)
Giant capillary0.84 (0.71, 0.92)0.92 (0.87, 0.96)
Intra-class correlation coefficient of quantative measurements (95% CI)
Density0.87 (0.88, 0.92)0.92 (0.91, 0.97)
Apex0.94 (0.93, 0.97)0.97 (0.96, 0.99)
Arterial0.88 (0.87, 0.93)0.96 (0.95, 0.99)
Venous0.91 (0.90, 0.96)0.96 (0.95, 0.99)
Total width0.94 (0.93, 0.97)0.98 (0.98, 0.99)

Inter- and intra-observer reliability of quantitative parameters showed substantial to almost perfect agreement. Certain qualitative parameters (architecture, avascularity, haemorrhage, ramified, and bushy capillaries) showed moderate to substantial inter-observer agreement and substantial intra-observer agreement, whereas other parameters including tortuous and bizarre capillaries showed moderate to poor inter-observer agreement.

Conclusions:

1) All quantitative and some qualitative parameters are highly reliable in terms of inter- and intra-observer agreement.

2) Other qualitative parameters, including tortuosity, are less reliable.

3) Capillaroscopy is likely to be a useful diagnostic tool and an outcome measure in studies of SS-related microvascular disease, provided that parameters selected are those with high reliability.

To cite this abstract, please use the following information:
Hofstee, Herman, Serne, Erik, Roberts, Chris, Hesselstrand, Roger, Scheja, Agneta, Moore, Tonia, et al; High Reliability of Nailfold VideocapillaroscopyAn Outcome Measure for Systemic Sclerosis-Related Microvsacular Disease? [abstract]. Arthritis Rheum 2010;62 Suppl 10 :1623
DOI: 10.1002/art.29389

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