Digital pitting scars are associated with a severe disease course and death in systemic sclerosis: A study from the EUSTAR cohort

Objective: Digital pitting scars (DPS) are frequent, but little studied in SSc to date. Methods: An analysis of SSc patients enrolled in the EUSTAR database. Primary objectives were to (i) examine DPS prevalence; (ii) examine whether DPS are associated with digital ulcers (DUs) and active digital ischaemia (DUs or gangrene); and (iii) describe other associations with DPS including internal organ complications. Secondary objectives were whether DPS are associated with (i) functional impairment; (ii) structural microvascular disease; and (iii) mortality. Descriptive statistics and parametric/non-parametric tests were used. Binary logistic regression was used to examine the association between DPS and DUs, active digital ischaemia and mortality. Results: A total of 9671 patients were included with reported DPS at any time point (n = 4924) or 'never' DPS (n = 4747). The majority (86.9%) were female and mean age was 55.7 years. DPS were associated with longer disease and Raynaud's duration (both P ≤ 0.001). DPS were associated with interstitial lung disease, pulmonary hypertension, conduction blocks, telangiectases, calcinosis (all P ≤ 0.001) and joint synovitis (P = 0.021). Patients were more likely to have more severe capillaroscopic abnormality and greater hand functional impairment. Multivariable logistic regression analyses showed that DPS were associated (odds ratio) with DUs: 22.03 (19.51-24.87), active digital ischaemia: 6.30 (5.34-7.42) and death: 1.86 (1.48-2.36). Conclusion: DPS are associated with a severe disease course including death. The impact of DPS on hand function and ischaemia is significant. The presence of DPS should alert the clinician to a poor prognosis and need to optimize the therapeutic strategy.