Risk factors for bone loss in juvenile-onset systemic lupus erythematosus: a prospective study

Abstract

Objective Juvenile-onset systemic lupus erythematosus (JoSLE) is associated with low bone mass for age and fractures; nevertheless, risk factors for bone impairment are poorly understood. The aim of this study was to evaluate risk factors for bone mass loss in JoSLE patients. Methods Forty-nine female JoSLE patients were evaluated at baseline and after a 3.5-year follow-up regarding clinical, laboratory (including bone turnover markers), areal bone mineral density (aBMD) and bone microarchitecture parameters using high-resolution peripheral quantitative computed tomography (HR-pQCT). Based on the difference between final and baseline aBMD value, the patients were divided into three groups: aBMD gain (BG), aBMD loss (BL) and aBMD no change (NC). Results The mean patient age was 18.7 ± 3.3 years. Sixty-one percent of patients presented with aBMD gain, 18.4% aBMD loss, and 20.4% remained stable during this follow-up period. Comparing the BL with the BG group, there was a higher frequency of alcohol consumption ( p = 0.009), a higher frequency of inadequate calcium intake ( p = 0.047) and lower levels of baseline procollagen type 1 amino-terminal propeptide (P1NP) ( p = 0.036) in the BL group. Moreover, worsening of HR-pQCT parameters trabecular volumetric density ( p = 0.003) and cortical thickness ( p = 0.009) was observed in the BL group. In addition, a higher frequency of renal activity was observed comparing the BL + NC with the BG group ( p = 0.036). Conclusions This is the first longitudinal study that has analyzed the risk factors of bone loss in JoSLE patients. The authors emphasize the importance of evaluating lifestyle habits and renal disease activity in these young women. Furthermore, this study suggests that trabecular and cortical compartments deteriorated, and low levels of P1NP may be a predictor of bone impairment in JoSLE.