Serum Calcification Propensity Is Independently Associated With Disease Activity In Systemic Lupus Erythematosus

BackgroundSystemic lupus erythematosus (SLE) is associated with severe cardiovascular complications. The T-50 score is a novel functional blood test quantifying calcification propensity in serum. High calcification propensity (or low T-50) is a strong and independent determinant of all-cause mortality in various patient populations.MethodsA total of 168 patients with >= 4 American College of Rheumatology (ACR) diagnostic criteria from the Swiss Systemic lupus erythematosus Cohort Study (SSCS) were included in this analysis. Serum calcification propensity was assessed using time-resolved nephelometry.ResultsThe cohort mainly consisted of female (85%), middle-aged (43 +/- 14 years) Caucasians (77%). The major determinants of T-50 levels included hemoglobin, serum creatinine and serum protein levels explaining 43% of the variation at baseline. Integrating disease activity (SELENA-SLEDAI) into this multivariate model revealed a significant association between disease activity and T-50 levels. In a subgroup analysis considering only patients with active disease (SELENA-SLEDAI score >= 4) we found a negative association between T-50 and SELENA-SLEDAI score at baseline (Spearman's rho -0.233, P = 0.02).ConclusionsDisease activity and T-50 are closely associated. Moreover, T-50 levels identify a subgroup of SLE patients with ongoing systemic inflammation as mirrored by increased disease activity. T-50 could be a promising biomarker reflecting SLE disease activity and might offer an earlier detection tool for high-risk patients.