European multicentre study validates enhanced liver fibrosis test as biomarker of fibrosis in systemic sclerosis.

Objectives: To validate enhanced liver fibrosis (ELF) test and its components-amino-terminal propeptide of procollagen type III (PIIINP), tissue inhibitor of matrix metalloproteinase-1 (TIMP-1) and HA-as biomarkers of fibrosis in SSc in an independent, international, multicentre cohort.

Methods: Two hundred and fifty-four SSc patients from six Rheumatology Centres were included. Sera were collected and stored according to EUSTAR biobanking recommendations and analysed through automated high throughput diagnostics. Statistical analysis was performed with SPSS software.

Results: Two hundred and forty-seven SSc patients (mean age 55.7 ± 13.9 years, 202 F) were analysed. ELF score, TIMP-1 and PIIINP levels were higher in males (P = 0.0197, P = 0.0107, P = 0.0108 respectively) and in dcSSc (P = 0.001, P = 0.0008, P < 0.0001 respectively). ELF score and the single markers significantly correlated with modified Rodnan skin score (r = 0.37, P < 0.0001), disease activity and severity (P < 0.0001 for all markers, except for HA P = 0.0001) and inversely with forced vital capacity, (FVC) % (TIMP-1, r = -0.21, P = 0.0012; PIIINP, r = -0.26, P = 0.0001), TLC% (ELF score, r = -0.20, P = 0.0036; TIMP-1, r = -0.32, P < 0.0001; PIIINP, r = -0.28, P < 0.0001), diffusion capacity of the lung for carbon monoxide (DLCO) % (P < 0.0001 for all markers, except for HA P = 0.0115). Multivariate analysis indicated that age (P < 0.001), modified Rodnan skin score (P < 0.001) and DLCO% (P = 0.005) were independently associated with ELF score.

Conclusion: Between the first and this validation studies, the value of the ELF score as independent marker of skin and lung involvement in SSc is confirmed in 457 patients. A longitudinal study is on-going to identify an SSc specific algorithm with predictive value for skin and lung progression.