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
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.
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.
These are summarised in the table.
|Inter-observer reliability||Intra-observer reliability|
|Weighted Kappa of ordered categories (95% CI)|
|Architecture||0.72 (0.55, 0.82)||0.75 (0.64, 0.83)|
|Avascularity||0.61 (0.37, 0.75)||0.74 (0.62, 0.82)|
|Haemorrhage||0.56 (0.16, 0.79)||0.73 (0.57, 0.86)|
|Tortuous||0.39 (0.25, 0.50)||0.68 (0.60, 0.76)|
|Ramified||0.58 (0.30, 0.73)||0.73 (0.59, 0.84)|
|Bushy||0.73 (-0.02, 0.90)||0.80 (0.58, 0.94)|
|Bizarre||0.21 (0.00, 0.32)||0.76 (0.55, 0.92)|
|Mega capillary||0.76 (0.64, 0.84)||0.87 (0.82, 0.91)|
|Giant capillary||0.84 (0.71, 0.92)||0.92 (0.87, 0.96)|
|Intra-class correlation coefficient of quantative measurements (95% CI)|
|Density||0.87 (0.88, 0.92)||0.92 (0.91, 0.97)|
|Apex||0.94 (0.93, 0.97)||0.97 (0.96, 0.99)|
|Arterial||0.88 (0.87, 0.93)||0.96 (0.95, 0.99)|
|Venous||0.91 (0.90, 0.96)||0.96 (0.95, 0.99)|
|Total width||0.94 (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.
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