POS0884 THE ENHANCED LIVER FIBROSIS (ELF) SCORE AS A BIOMARKER OF SKIN FIBROSIS IN SYSTEMIC SCLEROSIS

Abstract

Background:Serum fibrotic markers for systemic sclerosis (SSc) remain limited. The Enhanced Liver Fibrosis (ELF) score, originally derived and validated in patients with chronic liver disease, is an algorithm combining 3 serum markers, known as procollagen type III amino terminal propeptide (PIIINP), tissue inhibitor of metalloproteinases 1 (TIMP-1), and hyaluronic acid (HA). The combined score was proved to be superior to the single components in reflecting the severity of liver fibrosis. However, the performance of ELF score and its components has not been fully validated in SSc.Objectives:To investigate PIIINP, TIMP-1, HA, and the combined algorithm ELF score as fibrotic markers for SSc skin involvement.Methods:Eighty SSc patients (44 dcSSc and 36 lcSSc), fulfilling the 2013 ACR/EULAR criteria with the absence of chronic liver diseases, were enrolled. Eighty age- and sex- matched healthy controls were also included. Serum PIIINP and HA levels were quantified by chemiluminescence immunoassay. Serum TIMP-1 levels were determined by enzyme-linked immunosorbent assay. The ELF score was calculated using the formula ELF score= 2.494 + 0.846*ln(HA) + 0.735*ln(PIIINP) + 0.391*ln(TIMP-1). Results were correlated with clinical profiles including modified Rodnan skin score (mRSS) and interstitial lung disease (ILD).Results:Compared with healthy controls, patients with SSc showed significantly elevated serum PIIINP (11.2±4.8 vs. 5.73±1.4μg/L, p<0.001), TIMP-I (123.7±78.6 vs. 67.8±26.5 ng/ml, p<0.001), and ELF score (10.5±0.9 vs. 9.7±0.4, P<0.001). Even higher levels of PIIINP, TIMP-1, and ELF score were observed in dcSSc patients, compared with lcSSc patients (p<0.001, p=0.024, p=0.003, respectively). No significant difference was found in the levels of serum HA between patients and controls. Strong correlations were observed between mRSS and ELF score (r=0.54, p<0.001), and between mRSS and PIIINP(r=0.62, p<0.001), whereas only weak correlations could be observed between mRSS and TIMP-1 (r=0.28, p=0.02), and between mRSS and HA (r=0.26, p=0.03). When stratified by ELF score, using cutoffs proposed for liver fibrosis and cirrhosis, SSc patients with ELF<9.8 showed the lowest mRSS on average, while patients with ELF>11.3 showed the highest (p<0.001). When stratified by serum PIIINP levels, using the 25th and 75th percentiles, SSc patients with serum PIIIINP levels<7.8μg/L showed the lowest mRSS on average, while patients with PIIINP>14.0μg/L showed the highest (p<0.001). Neither the ELF score nor its components showed significant difference between patients with and without ILD.Conclusion:The ELF score could be used for reflecting the severity of overall skin involvement in SSc, and serum PIIINP also increased in parallel with the increase of mRSS. Longitudinal prospective studies exploring ELF score or serum PIIINP as fibrotic markers and outcome measures of SSc are warranted.