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Abstract
Background Serum uric acid (SUA) is a risk factor for the development of renal involvement in systemic lupus erythematosus (SLE), but the effect of SUA on renal involvement in specific genders and ages is not well known. We evaluated the association between SUA and the development of renal involvement in premenopausal female SLE patients.
Methods We retrospectively reviewed 155 premenopausal female patients with newly diagnosed SLE in a tertiary medical center. Baseline characteristics including SUA were compared between those who did (n = 48) or did not (n = 107) develop renal involvement. Patients without baseline renal involvement were followed up to identify factors affecting future renal involvement. Time-averaged SUA was divided into four categories of increasing levels (Q1, Q2, Q3, and Q4).
Results At baseline, patients with renal involvement showed higher SUA than patients without renal involvement (mean, 6.3 vs. 4.2 mg/dL, p < 0.001). Among 107 patients without baseline renal involvement (median follow-up of 6.6 years), 28 (26.2%) patients developed renal involvement. Although baseline SUA did not differ between both groups, patients with developing renal involvement showed higher time-averaged SUA (median, 4.4 vs. 4.1 mg/dL, p = 0.001) and higher last SUA (median, 4.9 vs. 3.8 mg/dL, p < 0.001) than those without developing renal involvement. The incidence of developing renal involvement in each time-averaged SUA quartile was as follows; 7.1% in Q1, 14.3% in Q2, 38.5% in Q3, and 40.6% in Q4 (figure 1). In multivariate Cox regression analysis, Q3 and Q4 groups had higher risk of developing renal involvement than Q1 group, with hazard ratios of 6.242 (p = 0.022) and 6.140 (p = 0.018), respectively.
Conclusions In premenopausal female SLE patients, high baseline SUA is associated with renal involvement at diagnosis. In addition, high time-averaged SUA may contribute to developing future renal involvement in patients without baseline renal involvement.
Incidence of developing renal involvement according to time-averaged serum uric acid level in premenopausal female patients with systemic lupus erythematosus. Q1: < 3.9 mg/dL (n = 28), Q2: 3.9–4.1 mg/dL (n = 21), Q3: 4.2–4.6 mg/dL (n = 26), and Q4: ≥ 4.7 mg/dL (n = 32), respectively.
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