High prolactin levels are independently associated with damage accrual in systemic lupus erythematosus patients

Objective: to determine whether prolactin levels are independently associated with disease damage in systemic lupus erythematosus (SLE) patients. Methods: these cross-sectional analyses were conducted in SLE patient members of the Almenara Lupus Cohort who were seen between January 2012 and June 2013. Disease damage was ascertained with the System Lupus International Collaborating Clinics/American College of Rheumatology (SLICC/ACR) damage index (SDI). Prolactin was measured in ng/ml. The association between prolactin levels and the SDI (total and its domains) was evaluated using Spearman's correlation. Subsequently, adjusted Poisson regression models were performed to evaluate these associations. Results: 160 patients were included. 147 (91.9%) were female; their median age at diagnosis was 33.4 (interquartile range (IQR): 26.0-44.3) years; their disease duration was 5.5 (IQR: 2.6-9.7) years. The median prolactin value was 16.8 (IQR: 11.8-24.5) ng/ml. After adjusting for confounders in the Poisson regression model the estimated rate ratios (RR) and 95% confidence interval (CI) for each 10 ng/ml increment of prolactin were 1.13 (95% CI 1.60-1.20, p<0.001) for the total SDI score, 1.15 (1.03-1.28, p=0.003) for the renal domain and 1.41 (1.11-1.79, p=0.003) for the cardiac/peripheral vascular domains. Conclusions: there was a positive association between prolactin levels and the SDI (overall and its renal and cardiac/peripheral vascular domains), independently of other well-known risk factors.