Description of the characteristics of the nailfold capillary structure in healthy children: a multi-centric study.

Background: Nailfold videocapillaroscopy (NVC) is the primary diagnostic tool for the assessment of microcirculation in the pediatric population.
Objective: To define and standardize age-specific normal NVC patterns in healthy children and adolescents.
Methods: A cross-sectional observational multicentric study was conducted in 564 participants aged 5-17 years. Dino-Lite CapillaryScope 200 Pro Model MEDL4N Pro was performed at 200× magnification. Quantitative and qualitative NVC parameters were analysed separately for each age group and divided into four groups based on age categories.
Results: Of the 564 healthy participants, 54.9% were female. A total of 1184 images and 3384 capillaries were analysed. Positive correlations were observed between age and capillary density (P < 0.001, R = 0.450, CI95% 0.398-0.503). There was also a positive correlation between age and arterial/venous, loop diameter and capillary length, whereas there was a weak negative correlation between intercapillary distance. However, no correlation was found between age and capillary width. In addition, capillary density was significantly lower in the 5-7 age group compared with the other patient groups. Arterial limb diameter was lower in the 5-7 age group, while venous limb diameter was significantly wider in the 15-17 age group compared with the other patient groups. Dilated capillaries (8.7%), capillary tortuosity (14.4%), crossed capillaries (43.1%), micro-haemorrhages (2.7%) and avascular area (4.8%) were present in all age groups. Excellent intra- and interobserver ICC values were obtained for all parameters.
Conclusion: These findings hold potential significance for future studies, aiding in the analysis and differentiation of children suspected of rheumatological diseases with potential microangiopathy.
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