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.