Progressive capillary loss over a decade in patients with systemic sclerosis, in particular in patients with early digital ischaemic manifestations

Objective: Characteristic capillary abnormalities occur early in systemic sclerosis (SSc). Our aim was to study the longitudinal development of capillary density in SSc patients. Methods: Forty-eight consecutive patients with SSc fulfilling a follow-up of at least 8 years were retrospectively analysed for capillary loss over the observation period. Eleven had diffuse cutaneous SSc (dcSSc) and 37 limited cutaneous SSc (lcSSc). The median disease duration at first assessment was 2.5 years. Capillary density was determined by direct counting of capillaries in the distal row on eight fingers in a stereo-zoom microscope at 20 x magnification. Results: Capillary density decreased over the observation period in dcSSc (from median 5.1 to 4.4 loops/mm, p < 0.05) and in lcSSc (from 5.1 to 4.2 loops/mm, p < 0.001). No significant difference was found between the two forms at start or at follow-up. Digital ischaemic manifestations had already been found at the first assessment in 19 patients. They did not differ in capillary density from those without ischaemic manifestations at the first assessment (5.0 and 5.3 loops/mm), but did differ at follow-up (3.6 and 4.7 loops/mm, p < 0.001). Capillary loss was more pronounced in patients who already had digital ischaemic manifestations at the first assessment compared to those without (p < 0.02). Conclusion: In SSc, early digital ischaemic manifestations may precede a subsequent progressive capillary loss. The association between capillary loss and serious internal vascular complications remains to be studied.