Background Nail-fold capillaroscopy (NFC) is a non-invasive, in vivo diagnostic tool for the assessment of microvasculature of the proximal nail fold. The comprehensive approach based on assessment of four finger each hand excluding the thumbs (in total eight fingers are examined) is the gold standard for NFC evaluation and scoring. The patient is identified to have abnormal nailfold capillaries, if abnormality was present in any finger/nailbed. However, this process is time consuming and is not applicable in standard clinical practice. Therefore, a question was raised can a concise approach based on assessment of a smaller number of fingers be implemented in standard practice. The challenge to this hypothesis is that there may be marked variability in the nailfold morphology between different fingers, as abnormalities may only be seen in some but not all fingers.

Objectives 1. To evaluate the comparability of the concise to the comprehensive approach (the gold standard) represented as the percentage of agreement of the NFC patterns recorded from each approach. 2. To assess the statistical difference on comparing the concise approach score to the gold standard score.

Methods This was a prospective, cross sectional multicenter study. 164 Patients were recruited for this study. The patients’ cohort included systemic sclerosis, rheumatoid arthritis, psoriatic arthritis, systemic Lupus erythematosus, Behcet’s disease, Sjogren’s syndrome and mixed connective tissue diseases. Imaging sessions were carried following the national standard for NFC [1]. NFC with 200x magnification was used to capture panoramic nailfold videocapillaroscopy images. Images were recorded from 4-fingers each hand, excluding the thumbs. For each finger 5 parameters were assessed: density, architecture, hemorrhage, neoangiogenesis and dimension. Semiquantitative scoring system was implemented to score each parameter [2].

Results Considering the correct diagnosis using the gold standard score was 100%, the concise approach based on mean of the scores recorded from the middle and ring fingers both hands gave the correct pattern in 155/164 (94.5%) of the cases. There was no statistical difference between the comprehensive approach total score (3.5 + 0.76 [CI 95% 1.918 - 5.082]), when compared to the concise total score from 2 fingers both hands which was (3.25 + 2.87 [1.873 - 4.626], p= 0.18. There was no significant difference on comparing the right to the left hand fingers.

Conclusion Examining the NFC from middle and ring fingers in each hand, can be time saving and not inferior to the comprehensive NFC assessment. Concise approach can be used in the standard clinical practice and, in the meantime, are able to give an overall NFC picture reflecting the real state of the nailfold capillaries.

References [1]El Miedany et al. Towards a consensus on the clinical applications and interpretations of the nailfold capillaroscopy standards in clinical practice: An initiative by the Egyptian Society of Microcirculation. Arch Rheumatol 2023;38.

[2]Cutolo M, Sulli A, Smith V. How to perform and interpret capillaroscopy. Best Pract Res Clin Rheumatol 2013; 27:23748.

Acknowledgements: NIL.

Disclosure of Interests None Declared.