Background: No fully validated index is available for assessing overall disease activity in systemic sclerosis (SSc). Objectives: To estimate the effect of disease activity as measured by different disease activity indices on the risk of subsequent organ damage. Methods: The European Systemic sclerosis study group activity index (EScSG AI), the European Scleroderma Trials and Research Group Activity Index (r-EUSTAR AI), 12 point activity index proposed by Minier (12point AI) were calculated for 91 patients; the CRISS (The Composite Response Index for Systemic Sclerosis) for patients included after 2016. Data were analysed by parametric and non-parametric tests and logistic regression. Results: EscSG AI, r-EUSTAR AI and 12point AI correlated with lung involvement. EScSG AI and r-EUSTAR AI correlated with diffuse skin involvement. EscSG AI correlated with digital ulcers and diffuse cutaneous involvement and r-EUSTAR AI with renal crisis. Bivariate analysis showed an inverse correlation between the three disease activity scores and forced vital capacity (FVC) (p<0.001) and diffusing capacity for carbon monoxide (DLCO) (p<0.001) and positive correlation with pulmonary fibrosis (p<0.001), modified Rodnan skin score (mRSS) (p<0.001), health assessment questionnaire (HAQ) (p<0.001), systolic pulmonary pressure (sPAP) (p<0.001), C-reactive protein (CRP) (p<0.001) and capillaroscopy scoring (p<0.001) at both baseline visit and at the 3-year follow-up visit. Logistic regression revealed that baseline EScSG AI adjusted for gender and age and that baseline 12-point AI both adjusted and unadjusted predicted worse skin involvement at 3-year follow-up; while adjusted EScSG AI predicted decreasing of DLCO. Also, 12-point AI predicted decline of FVC and higher HAQ scores at 3-year follow up; while baseline r-EUSTAR AI was able to predict muscular deterioration, decline of FVC and the increase of HAQ score during 3 years of following. An active disease according to EScSG AI at first visit predicted progression of joint involvement while an active disease at baseline showed by r-EUSTAR AI predicted muscular deterioration, FVC and DLCO worsening, as well as an increasing in HAQ score during the follow-up period. r-EUSTAR AI was the only score to predict the decrease of FVC in a multiple regression prediction model [OR= 1.306 (1.025, 1.665), p=0.31] while baseline EScSG AI best predicted worsening of DLCO [OR=1.749 (1.104, 2.772), p=0.017]. Conclusion: Our study could not establish a gold standard to assess disease activity in SSc; especially EscSG AI and r-EUSTAR AI could quantify and predict major organ involvement in daily practice. CRISS can be useful as an outcome measure for patients with short disease duration included in clinical studies.

BackgroundCurrently there is no fully validated index for assessing overall disease activity in patients with systemic sclerosis (SSc).ObjectivesTo estimate the effect of disease activity as measured by 4 disease activity indices on the risk of subsequent organ damage in a EUSTAR center cohort.MethodsLongitudinal observational study; European Systemic sclerosis study group disease activity index (EScSG DAI), revised EUSTAR disease activity index (r-EUSTAR DAI), 12 point activity index proposed by Minier (12point DAI) were calculated for all patients; the CRISS (The Combined Response Index for Systemic Sclerosis) only for patients included after 2016. Student t-test/Mann-Whitney test, chi-square test were used to evaluate differences across subgroups; Pearson’s bivariate correlation/Spearman’s rank correlation coefficient to evaluate the association between variables. The predictive value of various variables for major organ involvement was assessed by Roc curves and univariate regression.Results91 patients were selected,77 females (84,61%), 51,65(13,20) years old at diagnosis, 49,45% diffuse subset.Disease activity scores were all higher in male patients and in patients with diffuse cutaneous involvement, digital ulcers(DU), lung fibrosis, scleroderma renal crisis (SRC), arrythmias, muscle atrophy, gastric involvement, antitopoisomerase-1 positive, EscSG DAI correlated with forced vital capacity (FVC)(r=0.73,p<0.001), DLCO(r=0.68,p<0.001), DU(x2= 3.08,p=0.05), lung fibrosis(x2=10.90,p<0.0), systolic pulmonary arterial pressure (sPAP) (r=0.54,p<0.001), muscle atrophy (x2=11,58,p=0.001), diffuse subset (x2=11,46,p=0.001).R- EUSTAR DAI correlated with FVC(r=0.6,p<0.001), DLCO(r=0,58,p<0.001), diffuse subset(x2=9,52,p<0.01), contractures(x2=11,23,p=0.001), muscle weakness(x2= 6,61,p=0.01), muscle atrophy (x2=10,19, p<0.001), SRC (x2=4,74, p=0.02) and sPAP(r=0.5,p<0.001).12 point DAI correlated with FVC(r=0.57,p<0.001), DLCO(r=0.66,p<0.001) and sPAP(r=0.42,p<0.001).EscSG predicted well lung fibrosis (AUC=0.79,p<0.001), DU (AUC=0.66,p<0.001), gastric involvement (AUC=0.73, p<0.01) and SRC (AUC=0.9,p=0.01). R-EUSTAR index also lung fibrosis (AUC=0.76,p<0.001), DU (AUC=0.82,p<0.01) and SRC (AUC=0.84,p=0.04).12point DAI was a good predictor for lung fibrosis(AUC=0.74,p<0.01), DU(AUC=0.78,p=0.05), gastric involvement(AUC=0.76,p=0.01).In the regression analysis, lung fibrosis(beta=0.5,95%CI=1,21-2,58,p<0.01), muscle atrophy (beta=1.49, 95%CI=1.02-2.19,p=0.03) and rhythm and conduction disturbancies (beta=1.98, 95%CI=1.31-2.99,p<0.001) were independent predictors for disease activity evaluated by EScSG. For 12-EUSTAR DAI none of the evaluated parameters proved to independently contribuite to disease activity. For 12point DAI items independently contributing to disease activity were gastric involvement (beta=2.46,95%CI=1.19-5.09, p=0.01) and muscle atrophy (beta=2.05, 95%CI=1.03-4.08,p=0.03).The CRISS cohort included 35 patients, 32 females(91,42%), 48.48(14.24) years old, 62.85% diffuse subset, medium disease duration 11.88(7...