Interrater Reliability of Nailfold Capillaroscopy in Systemic Sclerosis Using Widefield Microscopy

Jessica K. Gordon¹, Meng Zhang², Shervin Assassi³, Elana J. Bernstein⁴, Robyn T. Domsic⁵, Faye N. Hant⁶, Monique E. Hinchcliff⁷, Dinesh Khanna⁸, Ami A. Shah⁹, Victoria K. Shanmugam^10,11, Virginia D. Steen¹² and Tracy M. Frech¹³, ¹Rheumatology, Hospital for Special Surgery, New York, NY, ²Epidemiology and Biostatistics, Hospital for Special Surgery, New York, NY, ³Rheumatology, University of Texas Medical School at Houston, Houston, TX, ⁴Rheumatology, Columbia University College of Physicians & Surgeons, New York, NY, ⁵Medicine - Rheumatology, University of Pittsburgh, Pittsburgh, PA, ⁶Dept of Medicine, Medical University of South Carolina, Charleston, SC, ⁷Division of Rheumatology, Division of Rheumatology, Northwestern University, Feinberg School of Medicine, Chicago, IL, ⁸Division of Rheumatology, University of Michigan, Ann Arbor, MI, ⁹Rheumatology, Johns Hopkins University School of Medicine, Baltimore, MD, ¹⁰Director, Division of Rheumatology, The George Washington University, Washington, DC, ¹¹Division of Rheumatology, The George Washington University, Washington, DC, ¹²Rheumatology, Georgetown University Medical Center, Washington, DC, ¹³Div of Rheumatology, University of Utah, Salt Lake City, UT

Meeting: 2015 ACR/ARHP Annual Meeting

Date of first publication: September 29, 2015

Keywords: Clinical research methods, Diagnostic imaging, nailfold capillaroscopy, scleroderma and systemic sclerosis

Session Information

Date: Tuesday, November 10, 2015

Title: Systemic Sclerosis, Fibrosing Syndromes and Raynaud's - Clinical Aspects and Therapeutics Poster III

Session Type: ACR Poster Session C

Session Time: 9:00AM-11:00AM

Background/Purpose:

The presence of nailfold capillary (NFC) abnormality is part of the 2013 ACR/EULAR Classification Criteria for Systemic Sclerosis (SSc). NFC findings include the presence of capillary dilation, hemorrhage, and neoangiogenesis, and it has been shown that these patterns have prognostic value. Patients in the Prospective Registry of Early Systemic Sclerosis (PRESS) cohort (diffuse SSc patients with < 2 years disease duration) have NFC evaluation using widefield microscopy (WM) at eleven centers in the United States. Our objective in this study was to assess the interrater agreement of the PRESS investigators assessment of NFC abnormalities by WM in order to ensure the quality of our data collection.

Methods:

Investigators from the PRESS registry assessed 26 cases of patients with SSc without macrovascular changes or significant hand contractures who had been photographed using WM. The PRESS Investigators have attended training exercises to learn the capillaroscopic techniques, but no specific training was provided prior to this exercise. Each case was assessed for NFC dilation, hemorrhage, and neoangiogenesis (defined as bushy capillaries) and rated as normal, mild, moderate, or severe for each of these categories. Data were captured via surveymonkey and analyzed in two ways: 1.) using all 4 categorical variables and 2.) using a simplified approach where the variables were collapsed to normal vs abnormal. Krippendorf’s alpha reliability estimate was used to assess the interrater agreement between these categorical variables. The following values represent the following degrees of agreement: <0 – poor; 0-0.2 – slight; 0.21- 0.4 – fair; 0.41- 0.6 – moderate; 0.61-0.8 – substantial; and 0.81-1.0 – almost perfect agreement.

Results:

Intrarater reliability ranged from substantial to almost perfect agreement for NFC hemorrhage to substantial agreement for dilation of NFC loops to fair agreement for neoangiogenesis. Assessment with four variables showed improved agreement when compared to 2 variables. Results are presented in Table 1.

Interrater Reliability
	4 variables (normal, mild, moderate, severe)	2 variables (normal/abnormal)
NFC Hemorrhage – alpha (95% CI)	0.7991 (0.7528, 0.8403)	0.8205 (0.6801, 0.9262)
Dilated Capillary Loops – alpha (95% CI)	0.6538 (0.5930, 0.7093)	0.4869 (0.2846, 0.6934)
Neoangiogenesis – alpha (95% CI)	0.3738 (0.2820, 0.4644)	0.2706 (0.0879, 0.4527)
Table 1. Krippendorf’s alpha reliability estimate using 4 variables (normal, mild, moderate, severe) and using 2 variables for the 3 categories of NFC abnormality assessed.

Conclusion:

Fair inter-rater reliability was observed for neoangiogenesis, moderate to substantial reliability was observed for dilated capillary loops, and substantial to near perfect agreement was noted for reading of WM photomicrographs for NFC hemorrhage among PRESS investigators. This attests to quality data collection for this procedure. Classification of specific NFC abnormalities using the terms normal, mild, moderate, and severe is feasible and can be used reliably in registries. Whether NFC abnormalities carry prognostic significance in patients with early diffuse SSc is a subject for future study in the PRESS registry.

Disclosure: J. K. Gordon, Bayer, 5; M. Zhang, None; S. Assassi, Biogen Idec, 5,Boehringer Ingelheim, 5; E. J. Bernstein, None; R. T. Domsic, Biogen-Idec, 5,Bayer, 5; F. N. Hant, None; M. E. Hinchcliff, None; D. Khanna, Bristol-Myers Squibb, 2,EMD Serono, 2,Genentech and Biogen IDEC Inc., 2,Bayer, 5,Biogen Idec, 5,Cytori, 5,EMD Serono, 5,Forward, 5,Genentech and Biogen IDEC Inc., 5,Gilead, 5,Lycera, 5,Seattle Genetics, 5; A. A. Shah, None; V. K. Shanmugam, None; V. D. Steen, None; T. M. Frech, None.

To cite this abstract in AMA style:

Gordon JK, Zhang M, Assassi S, Bernstein EJ, Domsic RT, Hant FN, Hinchcliff ME, Khanna D, Shah AA, Shanmugam VK, Steen VD, Frech TM. Interrater Reliability of Nailfold Capillaroscopy in Systemic Sclerosis Using Widefield Microscopy [abstract]. Arthritis Rheumatol. 2015; 67 (suppl 10). https://acrabstracts.org/abstract/interrater-reliability-of-nailfold-capillaroscopy-in-systemic-sclerosis-using-widefield-microscopy/. Accessed .

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