Background Iloprost (ILO) and bosentan (BOSE) integrated therapy was demonstrated to improve microvascular structure in systemic sclerosis (SSc) patients, in two long-term follow up studies [1].

Objectives Since the alterations in capillary number seem to predict the incidence of clinical SSc complications [2], present study aimed to quantify, by nailfold videocapillaroscopy (NVC), long-term effects of BOSE treatment on nailfold capillary absolute number and their possible correlation with clinical parameters of the disease.

Methods Thirty SSc patients entered the study, with a follow up of for 4 years. Fifteen patients were treated with ILO mono-therapy (80 μg/day, for 5 continuous days, every 3 months), while other 15 patients, because of the onset of systolic pulmonary hypertension (sPAP) or digital ulcers (DUs) were treated with BOSE (125 mg twice/day) and ILO integrated therapy (ILO+BOSE). Nailfold capillaries absolute number, DU incidence, diffusing capacity of the lung for carbon monoxide (DLCO), sPAP and renal artery resistive index (RI) were evaluated yearly. Friedman test, Cochran's q test, Marginal homogeneity and mixed modelling were used to study variables with repeated measures. A p value lower then 0.05 was considered significant.

Results In the ILO+BOSE group, capillary absolute number was found to have a significant increase (p=0.01) from T0: 6.8±1.3 to T4: 7.8±1.5 (14.7%), whereas in the ILO group, a non-significant decrease in capillary number from T0: 7.18±0.5 to T4: 6.5±1.1 (9.4%) was found. According to multivariate analysis, the most significant associations, other then BOSE treatment, were observed between capillary number increase and baseline capillaroscopic “Early” pattern (p<0.0001), lcSSc subtype (p=0.001), while it was independent from other clinical characteristics. In the ILO+BOSE group there was a significant reduction in the annual incidence of new DUs from T0 (10/15 patients) to T4 (2/15 patients) (80%; p=0.0042) and no further negative significant changes were observed in DLCO and sPAP. On the contrary, in the ILO group, DLCO was significantly reduced (8.1%, p=0.039) and sPAP increased (15%, p=0.04) during the follow up. RI did not change significantly in both groups.

Conclusions Capillary absolute number count seems a reliable parameter to evaluate long-term effects of BOSE on microvasculature in SSc. A significant reduction in the annual incidence of new DUs and stabilization of lung function was observed and appeared to be associated to the increased number of capillaries during a four-years integrated treatment with BOSE and ILO.

1. Cutolo M et al. 2013;40:40–5.

2. Smith V et al. 2011;70:180–3.

Disclosure of Interest None declared