Laser speckle contrast analysis is a reliable measure of digital blood perfusion in Black Africans with systemic sclerosis

OBJECTIVESLaser speckle contrast analysis (LASCA) is evolving as a promising non-invasive tool to assess cutaneous microvascular function in systemic sclerosis (SSc). Reliability studies have mainly focused on Caucasian populations. To determine for the first time the inter-rater reliability of fingertip blood perfusion (BP) using LASCA in Black South African patients with SSc. METHODSConsecutive Black adult patients with SSc were evaluated for peripheral BP using LASCA. Mean BP in defined regions of interest for dorsal fingertips and volar fingertips were measured in two subgroups of 20 SSc patients, each by three independent operators. Two operators were experienced in the use of the LASCA instrument and one was newly trained. Standardised protocols for conditions were followed for all measurements. Inter-rater reliability was tested using the intraclass correlation coefficient (ICC). RESULTSThe majority (87.5%) of the 40 patients included were females and 67.5% had diffuse cutaneous SSc. The mean age (standard deviation) was 48.5 (9.9) years and the median disease duration (interquartile range) was 8.5 (4, 13) years. There was good to excellent agreement, inter-rater ICC (dorsal fingertip range: 0.86-0.97 and volar fingertip range: 0.85-0.96), in both subgroups irrespective of operator skill. CONCLUSIONSLASCA is a credible instrument in patients of Black ethnicity with SSc, and across operator experience.