Background/Purpose: Juvenile-onset systemic lupus erythematosus (JoSLE) is associated with low bone mass for age and fractures, nevertheless risk factors and predictors of bone involvement are poorly understood in this condition. The aim of this study was to evaluate the risk factors for bone mass loss in patients with JoSLE analyzing clinical and laboratory data and bone microarchitecture parameters.

Methods: This study enrolled a sample of 49 female JoSLE patients, all of them with diagnosis, according to ACR classification criteria (2012 SLICC). All these patients were evaluated at baseline and after 3.5 years of follow-up in relation to: clinical data associated with the disease, lifestyle habits, treatment, laboratory tests including bone turnover markers (N-terminal propeptide of type 1 collagen – P1NP; C-terminal telopeptide of type 1 collagen – CTX), areal bone mineral density (aBMD) by dual X-ray absorptiometry (DXA) at lumbar spine and hip and parameters of bone microarchitecture by high-resolution peripheral quantitative computed tomography (HR-pQCT) at distal tibia and radius. Vertebral fractures were analyzed using DXA (VFA, Genant’s method). aBMD changes above the least significant change were considered significant. Based on the difference between final and baseline aBMD value, the patients were divided into 3 groups: aBMD gain (BG), aBMD loss (BL) and aBMD no change (NC).

Results: The mean age of patients was 18.7 ± 3.3 years and the mean disease duration was 6.0 ± 3.9 years. Sixty-one percent of patients presented aBMD gain, 18.4% aBMD loss and 22.4% remained stable over this period of follow-up. Comparing the BL group with the BG group, there was a higher frequency of alcohol consumption (33.3 vs. 0%, p = 0.009), a higher frequency of inadequate calcium intake (66.7 vs. 26.7%, p = 0.047) and lower serum levels of baseline P1NP (52.42 ± 33.56 vs. 119.72 ± 85.78 ng/mL, p = 0.036) in the former group. Moreover, a worse evolution of HR-pQCT bone parameters: trabecular volumetric density at tibia (-16.36 ± 15.71 vs. -1.55 ± 10.83 mg/cm³, p = 0.003) and cortical thickness at tibia (-0.025 ± 0.09 vs. 0.054 ± 0.07 mm, p = 0.009) was observed in the BL group. In addition, a higher frequency of renal activity was observed when the BL and NC groups were associated and compared to the BG group (52.6 vs. 23.3%, p = 0.036). No significant differences were observed regarding other clinical, laboratorial and microarchitecture bone parameters and treatment.

Conclusion: This is the first longitudinal study in the literature that analyzed the risk factors of bone mass loss in JoSLE patients. The authors emphasize the importance of evaluating not only renal disease activity, but also lifestyle habits, mainly alcoholism and calcium intake in these young women. Furthermore, this study suggests that trabecular and cortical bone compartments were deteriorated in this disease and that low serum levels of P1NP may be a predictor of bone involvement in JoSLE.

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ACR Meeting Abstracts - https://acrabstracts.org/abstract/risk-factors-for-bone-loss-in-juvenile-onset-systemic-lupus-erythematosus-a-prospective-study/