• microcirculation
• nailfold capillaroscopy
• Sjögren’s Syndrome

Background: Nailfold capillaroscopy (NC) is a non-invasive, reproducible imaging method to assess microcirculation in rheumatic diseases. In contrast to well-defined capillaroscopic findings in patients with systemic sclerosis, specific capillaroscopic findings in Sjögren’s Syndrome (SS) have not been documented.

Methods: The literature was systematically reviewed in three databases (Pubmed/Embase/Web of Science) to identify the role of NC in SS. The results were gathered for capillaroscopic parameters, and in a second time, an overview of correlations between these with clinical and laboratory values was given. All original studies to date published were revised. A quality assessment was applied to all included studies based on: sample size, well described target population, presence of a control group, capillaroscopic tool specifications and/or standardly applied methodology, clear definitions and descriptions of capillaroscopic parameters, statistic analysis used. Following the systematic review of literature (SRL), a prospective monocentric study was carried out in the Rheumatology Unit (Department of Medicine, University of Perugia) from September to November 2019. The NC was performed on 14 healthy controls (HC) and 20 patients with Sjögren’s Syndrome (SS).
Either qualitative and quantitative assessment were applied aimed to identify more frequent capillaroscopic alterations and/or pattern. Statistical analysis was performed using Student’s t-test and Mann–Whitney U-test.

Results: The literature search resulted in 826 hits. Based on title and abstract screening 519 original studies were retained and of these, 18 full texts describe an assessment by NC in SS. Finally, seven studies passed the quality assessment and form the object of this review: five case-control studies (only two studies compared SS with HC) and two case-series. The studies included on average of 61 SS patients (range 18-136).
Five studies performed a quantitative assessment of the NC images describing presence of dilations and haemorrhages in SS whereas abnormal morphology and tortuosity were equally seen in SS patients as in HC. One study performed a semi-quantitative assessment and any significant difference between SS and HC was shown. Six studies performed a qualitative assessment describing normal, non-specific and scleroderma pattern in SS patients. Only one study suggests an association between Raynaud’s phenomenon (RP), anticentromere autoantibodies (ACA) and capillaroscopic findings, though the results were not confirmed by analysis in external cohorts.
In our study the only significant difference between SS and HC was observed for the mean number of enlarged capillaries. No capillaroscopic differences in SS patients with and without RP were found, SS patients with double positivity (anti-SSA/Ro, anti-SSB/La antibodies) more frequently showed haemorrhages than patients with isolated positive anti-SSA/Ro antibodies.

Conclusion: Until now, the nailfold capillaroscopic assessment in patients with SS has not been uniformly clarified. Overall, the reviewed studies in literature show that capillaroscopic findings observed in SS are not significantly different from those observed in HC. In our study we tried to overcome some limits of previous investigations. We observed two statistically significant differences between SS and HC. In particular, more enlarged capillaries was seen in SS. In addition an increased number of haemorrhages was observed in double positive SS also compared to subjects with isolated anti-Ro circulating antibodies. Further research in this domain and on a larger sample of patients is needed to attest the reliability of this results.