P096 A study on clinical characteristics and severity of salt-and-pepper pigmentation in systemic sclerosis

Abstract Skin manifestation is vital for the diagnosis and subclassification of systemic sclerosis (SSc). Salt-and-pepper pigmentation (SaPP) helps readily identify a case of systemic sclerosis (SSc) but is an overlooked manifestation in terms of prognosis. We will define the prevalence and characteristics of SaPP, explore its association, and develop a scoring system. Patients with SSc aged ≥ 18 years were recruited by convenience sampling. The pigment distribution, skin sclerosis severity and internal organ involvement were noted based on the revised preliminary SSc severity scale by Medsger et al. The SaPP severity (SaPPs) score was adopted from vitiligo scores due to its similar appearance. The construct validity and the photographic guide for various depigmentation levels were developed from the expert survey. Domains with experts having 70% agreement were incorporated into the score. The construct validity of the score was tested with Physician’s Global Assessment (PGA) and Patient Global Assessment (PtGA) as the anchors. The score was repeated monthly for test–retest reliability. Among 131 patients with SSc, there was SaPP (n = 74), diffuse SSc (n = 73), limited SSc (n = 40), SSc sine scleroderma (n = 4) and overlap syndromes (n = 14). Among the patients with SaPP (n = 74), 74% had symmetrical distribution and 61% experienced SaPP corresponding with areas of sclerosis. SaPP was associated with moderate-to-severe peripheral vascular disease [odds ratio (OR) 5.63, 95% confidence interval (CI) 1.27–24.9] and skin sclerosis (OR 3.27, 95% CI 1.03–10.4), and shorter disease duration of first non-Raynaud symptom (OR 0.81, 95% CI 0.68–0.97). The SaPPs score is a composite of the sum of each quadrilateral (0.25%) and the depigmentation level within each patch. A modified Lund and Browder chart was used to document the body, and the depigmentation was reported as 10%, 25%, 50%, 75%, 90% or 100%, as with the Vitiligo Area Severity Index. The mean SaPPs score was 3.5 (SD 4.1), with excellent correlation for inter-investigator observation (r = 0.94, P < 0.001). SaPPs score moderately correlated with PGA (r = 0.64, P < 0.001). The body surface area from the physician’s point of view highly correlated with the total body unit subcomponent of the SaPPs score (r = 0.78, P < 0.001). Among the patient-reported assessments, disease impact moderately correlated with the SaPPs score (r = 0.51, P < 0.001). Scores taken at two timepoints had an excellent correlation between them (r = 0.97, P < 0.001). The modified Rodnan Skin Score weakly correlated with the score (r = 0.32, P = 0.006). In conclusion, SaPP is seen in half of patients with SSc. It is symmetrical in many; however, it may or may not correspond to the areas of sclerosis. SaPP is independently associated with moderate-to-severe skin sclerosis, peripheral vascular disease and shorter disease duration. The SaPPs score can be used to measure SaPP disease severity.