Performance of finger systolic blood pressure measurement to detect digital occlusive arterial disease in systemic sclerosis

Objective Digital ulcers related to digital occlusive arterial disease (DOAD) are frequent in patients with SSc. Finger systolic blood pressure (FSBP) and digital-brachial pressure index (DBI) using laser Doppler flowmetry constitute a non-invasive means of detecting DOAD in SSc, although thresholds have yet to be established for defining DOAD. The purpose of this study was to ascertain FSBP and DBI thresholds to detect DOAD in SSc patients. The intra/interday reproducibility of curve reading by four vascular physicians in relation to finger pressure measurement was also investigated. Methods SSc patients were followed in this single-centre study (Rennes University Hospital, France) between November 2017 and October 2019.These patients underwent tests before and after heating at two visits spaced 10 days apart. DOAD was diagnosed on the basis of post-warming skin blood flow of <= 206 arbitrary units measured by laser Doppler flowmetry, contingent on previous results validated by arteriography as a gold standard. An interday kappa coefficient with a 95% confidence interval was used to assess reproducibility. Results Sixteen [10 females; mean age: 63 (9) years] SSc patients were included. Mean time interval between visits was 9 (5) days. The best FSBP threshold for DOAD diagnosis was 76 mmHg and DBI was 0.74 after warming. FSBP and DBI sensitivity/specificity were 59.1% (95% CI: 49.6, 68.5%)/92.5% (95% CI: 85.3, 99.6%) and 73.3% (95% CI: 64.9, 81.8%)/83.0% (95% CI: 72.9, 93.1%), respectively. Intra/interday reproducibility ranged from fair to good. Conclusion The conclusions drawn from this study suggest that FSBP <= 76 mmHg and DBI <= 0.74 thresholds are potentially reliable indicators of DOAD and demonstrate fair to good intra- and interday reproducibility.