Background Nailfold Capillaroscopy is a non-invasive diagnostic technique designed to evaluate small vessels of the microcirculation. The most important indication for capillaroscopy is Raynaud's phenomenon. The complexity and meticulous evaluation of the eight fingers is difficult to apply in daily practice given the limited availability of time to perform. For this reason it is necessary to develop simple and abbreviated techniques, to achieve an optimal and rapid evaluation of the patient.
Objectives Determine the performance of the method of the 4° finger for the diagnosis of SD pattern in patients with Raynaud's Phenomenon taking the eight finger pattern as a gold standard.
Methods Cross-sectional study with blinded and independent measurements. Nailfold Capillaroscopy was performed on the four fingers of each hand, except thumbs. Another observer evaluated the 4th finger of the hands. The interobserver agreement was made before carrying out the study and was 100%. The 8-finger method (gold standard) was considered positive when at least one finger has SD pattern and the 4° finger method was considered positive when at least one of them presents the SD pattern. We included patients older than 18 years with a diagnosis of Raynaud Phenomenon. Patients with thickening of the skin in the nailfold, digital lesion that made it difficult to assess (trauma, amputation, burns, etc.) and patients who did not consent to the procedure were excluded.
Results We included 78 patients, 90% was female. The mean age was 53 years (DS +/- 13.5). Sixty-three patients had a score of eight fingers positive (cases) and 15 had a score of eight fingers negative (controls). The sensitivity of the 4° finger evaluation method was 89% (95% CI: 82–96%) and 93% specificity (95% CI: 88–99%). The positive predictive value of this method was 98% (95% CI: 95–100%) and the negative predictive value was 67% (95% CI: 56–77%). The positive likelihood ratio was 13 (95% CI: 2–89).
Conclusions The simplified method of the 4° finger showed good performance for the diagnosis of SD pattern compared to the standard method of evaluation of the 8 fingers.
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Disclosure of Interest None declared