Objectives: To investigate factors predictive of future lupus nephritis development when systemic lupus erythematosus (SLE) is diagnosed.
Methods: Patients with newly diagnosed SLE without renal manifestations were followed for development of lupus nephritis, comparing findings at baseline between those who did or did not develop nephritis. Albumin-to-globulin ratio (AGR) was calculated as albumin/(total protein-albumin). Cox proportional hazard model was used to identify predictors of lupus nephritis.
Results: Of 278 patients, 241 did not and 37 did develop lupus nephritis during follow-up. On univariate analysis, young age, low C3, low C4, high anti-dsDNA titre, anti-Sm antibody, anti-RNP antibody and low AGR were associated with a higher risk of lupus nephritis. On multivariate analysis, factors predictive of nephritis were age [adjusted hazard ratio (aHR) 0.928, 95% confidence interval (CI): 0.895-0.961, p < 0.001], C3 (aHR 0.977, 95% CI: 0.966-0.989, p < 0.001), anti-dsDNA titre (aHR 1.004, 95% CI: 1.000-1.007, p = 0.026) and anti-Sm antibody (aHR 2.097, 95% CI: 1.040-4.229, p = 0.038). In particular, a low AGR (aHR 4.972, 95% CI: 2.394-10.326, p < 0.001) was strongly associated with an increased risk of future lupus nephritis development.
Conclusion: Young age, low C3, high anti-dsDNA titre and presence of anti-Sm antibody at diagnosis of SLE were associated with a risk of future lupus nephritis, but the hazard was greatest with a low AGR value, suggesting that a greater proportion of immunoglobulin relative to total protein is associated with the development of nephritis.
Keywords: Albumin-to-globulin ratio; Lupus nephritis; Systemic lupus erythematosus.
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