Nailfold capillaroscopy (NC) and laboratory tests for antinuclear antibodies (ANA) are routinely used in parallel for detection of emerging connective tissue disease (CTD) in patients with Raynaud's phenomenon (RP).
The aim of this study was to assess the associations between distinct nailfold capillary abnormalities and concomitant autoantibodies in patients with incipient RP without previously known CTD.
Patients with incipient RP without previously known CTD were included in this retrospective analysis. We analysed the association of particular capillary abnormalities (reduced density, avascular fields, dilations, giant capillaries, haemorrhages, tortuosity, ramifications, oedema) with ANA and ANA subsets (anti-Scl-70, anti-CENP-B, anti-U1-RNP, anti-dsDNA, anti-SSA(Ro), anti-SSB(La), anti-Sm, and anti-Jo-1 antibodies). We also developed a score that allows the estimation of each patient's individual probability for the presence of an ANA titre ≥ 1:160.
The final analysis comprised 2971 patients. Avascular fields, giant capillaries, reduced capillary density, and capillary oedema were closely related to an ANA titre ≥ 1:160. Both giant capillaries and avascular fields were associated with anti-Scl-70 and anti-CENP-B antibodies. Only a weak association was found between giant capillaries and anti-U1-RNP antibodies. Each patient's individual probability for the presence of an ANA titre ≥ 1:160 can be represented by a sum score comprising giant capillaries, reduced density, avascular fields, ramifications, and oedema as well as patients' sex and age.
In patients with incipient RP, anti-Scl-70 and anti-CENP-B antibodies are related most specifically to distinct capillary alterations. Although a sum score can represent the patient's probability for elevated ANA titres, NC cannot substitute for immunological tests in patients with incipient RP.