Estimated glomerular filtration rate and renal resistive index as possible predictive markers of mortality in systemic sclerosis

Objective: Subclinical nephropathy is underestimated in systemic sclerosis (SSc). Study aim is to evaluate the role of renal resistance indices (RRI) and estimated glomerular filtration rate (eGFR) assessed by Chronic Kidney Disease Epidemiology Collaboration (CKD-EPI) as predictive markers of mortality during 10 years of follow-up in SSc patients.Methods: 181 SSc patients (60 years, 152 females) were enrolled. At baseline, the GFR was estimated in 181 SSc patients and RRI was measured in 122 SSc patients. During a follow-up of 10 years we recorded the main complications of disease, date and causes of death.Results: eGFR shows a linear negative correlation with RRI. RRI showed a correlation with systolic pulmonary artery pressure (sPAP). Overall survival is lower in SSc patients with eGFR<60 ml/min and RRI >0.70 than in SSc patients with eGFR>60 ml/min (p<0.0001) and with RRI<0.70 (p<0.01) both for mortality due to SSc and all causes. In multivariate analysis, eGFR<60 ml/min [HR 6.429, 95%CI (1.006-41.08), p<0.05] and forced vital capacity (FVC) [HR 0.954, 95%CI (0.911-1), p<0.05] are predictive markers of mortality due to SSc, while eGFR [HR 3.617, 95%CI (1.370-9.554), p<0.01], RRI [HR 0.210, 95% CI (0.068-0.649), p<0.01], age [HR 1.062, 95% CI (1.023-1.103), p<0.01], FVC [HR 0.967, 95%CI (0.946-0.989), p<0.01] and disease activity index (DAI) [HR 1.663, 95%CI (1.262-2.191), p<0.0001] are predictive markers of mortality due to all causes. Conclusion: We demonstrate that eGFR is a predictive marker of mortality due to SSc and to all causes, conversely RRI is predictive marker of mortality due to all causes.