A study reported that the nail-fold capillaroscopy (NFC) test, used in the diagnosis of systemic sclerosis (SSc), can also be used to distinguish between forms of Raynaud’s disease.
The study, “Absence of Scleroderma pattern at nail fold capillaroscopy valuable in the exclusion of Scleroderma in unselected patients with Raynaud’s Phenomenon,” was published by Lesley-Anne Bissell and her colleagues from research units in Leeds, England, in the journal BMC Musculoskeletal Disorders.
The NFC test is a non-invasive method to evaluate microcirculation in patients by detecting abnormalities in blood vessels. This test has been used in the diagnosis of SSc because the disease is associated with a pattern characterized by the presence of early, active, or late abnormalities in the blood vessels. The NFC pattern correlates with SSc disease duration, severity, and can help predict future organ damage.
A few studies have indicated that the SSc NFC pattern also happens in patients with secondary Raynaud’s phenomenon (sRP), while patients with primary Raynaud’s phenomenon (pRP) usually have normal blood vessels.
The study’s aim was to analyze whether the NFC test could detect the presence of SSc in patients with Raynaud’s syndrome, and defining which patients have primary or secondary Raynaud’s phenomenon.
The study included 347 patients, mostly women, who were referred to an SSc center between January 2009 and October 2013. Patients were classified as having pRP; if they had Raynaud’s with no features of connective tissue disease (CTD)/antibody positivity; or sRP when diagnosed with a non-SSc connective tissue disease such as systemic lupus erythematosus (SLE) or undifferentiated CTD (UCTD).
The NFC exam consisted of applying a drop of immersion oil on the nail beds of the fingers except the thumbs, after which the nail-fold capillaries were examined by microscope or video-microscopy. NFC patterns were classified as normal, non-specific, or with an SSc pattern (early, active, or late).
Compared to the original diagnosis that the patients had before the study, the NFC results indicated that 16 percent of the patients did not to have true Raynaud’s; 20 percent had primary Raynaud’s; 50 percent had seconary Raynaud’s; and 15 percent had SSc.
The NFC test indicated that SSc patterns were observed in 71 percent of the SSc patients; in 17 percent with sRP; in 13 percent with pRP; and in 7 percent with no Raynaud’s phenemonon. The test also identified which patients met the criteria for SSc (VEDOSS or 2013 ACR/EULAR criteria) with 71 percent sensitivity and 95 percent specificity.
Together, the results indicated that since the absence of an SSc NFC pattern is important to exclude the presence of the disease, the NFC test could be performed in Raynaud’s patients to help distinguish between primary or seconary Raynaud’s phenomenon.