Background/Purpose: Nailfold Video Capillaroscopy (NVC) is a reliable method to qualitatively differentiate Primary (PRP) from Secondary Raynaud Phenomenon (SRP) through diagnosis of the “early scleroderma pattern” (1, 2). Quantitative evaluation by NVC was demonstrated to be of great value for the analysis of abnormal capillary parameters (2). The purpose was to assess the presence and localization of capillary diameter abnormalities (>20μm),before the transition to SRP. Moreover, to find a threshold value for those dilations, associated to the development of giant capillaries (>50 μm), pathognomonic for the “early scleroderma pattern” (SSc).

Methods: We realized a case-control study, over a total population of 191 RP subjects with a NVC follow-up of 42.77±35.80 months. Two gruoups were identified, uniform for demographic characteristics (gender, age), RP duration (p= 0.98), treatments (p=0.13) and comorbidities (p=0.13). RP subjects were classified as SRP SSc-associated, based on the appearance of the “early” scleroderma pattern and/or ANA positivity, or confirmed with PRP. One operator performed the NVC and results were separately checked by two experts with an inter-rater/intra-rater proportion of agreement of 90% and 96%, respectively. Another observer measured on NVC images the major dilation of capillary branches (arterial, venous, apical) using a dedicated software (Videocap, DS MediGroup, Milan, Italy). More then 6112 images were analyzed. The mean diameter value for each enlarged branch (arterial, venous, apical) and the total mean diameter, were calculated. Statistics were performed by non-parametric tests. ROC curve was performed to find the SSc development associated threshold value.

Results: A statistically significant difference was found in SRP subjects, before the transition, compared to PRP subjects, for diameter values of dilations in both arterial (35.30 ± 8.79 VS 27.84 ± 5.52 μm; p<0.0001) and venous (37.19 ± 6.58 VS 28.86 ± 4.48 μm; p<0.0001) branches. No significant differences were observed for apical dilations (32.64 ± 5.77 VS 30.81 ± 6.35 μm; p=0.07). ANAs were observed in 56.2% of SRP patients (p= <0.0001). No confounding effect was observed for other demographic and clinical data. Kaplan-Meier analysis showed that 50% of SRP patients evolved to SSc in 20 months. The threshold value associated with SSc development was 30.16 μm, determined through ROC curve, with a sensitivity/specificity of 0.85/0.63 respectively, a negative predictive value (NPV) of 0.92 and a positive predictive value (PPV) of 0.44.

Conclusion: Abnormal dilations of arterial and/or venous branches, at baseline, are detectable by NVC, and are significantly more often expressed in RP subjects that will develop a SRP.Progression to “giant” capillaries (>50 μm) pathognomonic for the “early” NVC scleroderma pattern seem to be unlikely for subjects affected by RP with mean capillary diameter lower then 30.16 μm (NPV 0.92). Therefore, it is advisable to perform always the qualitative/quantitative integrated NVC during the follow up of all patients affected by RP.

References: 1) Cutolo M et al. 2000;27:155–60. 2) Cutolo M et al. Best Pract Res Clin Rheumatol. 2013;27(2):237-48. 3) Smith V at al. J Rheumatol. 2013;40:2023-8

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ACR Meeting Abstracts - https://acrabstracts.org/abstract/raynaud-phenomenon-subjects-with-abnormal-capillary-dilations-show-a-risk-threshold-diameter-value-for-the-transition-to-the-capillaroscopic-early%ef%bf%bd-scleroderma-pattern-a-case-control-study/