Quantitation of microcirculatory abnormalities in patients with primary Raynaud's phenomenon and systemic sclerosis by video capillaroscopy

Objective. To assess nailfold capillary density and dimensions in patients with primary Raynaud's phenomenon (PRP), limited cutaneous systemic sclerosis (LSSc) and diffuse cutaneous SSc (DSSc), and healthy control subjects. Methods. Using the technique of nailfold video capillaroscopy, capillary density and dimensions were averaged from all visible capillaries in a 3 mm length of the nailfold from right and left ring fingers of each subject. Twenty healthy control subjects, 15 patients with PRP, 13 patients with DSSc and 21 patients with LSSc were examined. Intra-observer and inter-observer variability were calculated in 18 and 23 patients, respectively. Results. There were significant trends for capillary density to fall and for all dimensions to rise across the four groups (P < 0.0001 for density and all dimensions, order healthy controls, PRP, DSSc and LSSc). Intra- and inter-observer reproducibility studies showed that although there was good correlation between and within observers, the limits of agreement were between +/-25-50% indicating lack of reproducibility. Conclusions. Microcirculatory abnormalities can be quantified using the technique of video capillaroscopy and were most marked in patients with LSSc.