Background Lupus nephritis is a type of major organ involvement in systemic lupus erythematosus (SLE) patients that leads to higher rates of morbidity and mortality and may present initially in 28% of SLE patients. However, there are limited data available on clinical differences or predictors for biopsy-proven lupus nephritis in established versus newly diagnosed SLE cases. Methods Adult patients undergoing kidney biopsy for the first time with a diagnosis of lupus nephritis were eligible for

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... nclusion. Patients were categorized into two groups: those with previously diagnosed SLE and those with newly diagnosed SLE by kidney biopsy. Factors associated with newly diagnosed SLE were determined using logistic regression analysis. Results There were 68 patients diagnosed with lupus nephritis by kidney biopsy. Of those, 31 cases (45.58%) were newly diagnosed. The newly diagnosed SLE group was significantly older (36.87 vs 30.95 years) and had a lower proportion of females (74.19% vs 91.89%) than the previously diagnosed group. A new-onset hypertension was the only factor independently associated with newly diagnosed SLE by kidney biopsy. The adjusted odds ratio (95% CI) was 5.152 (1.046, 25.363). Conclusions Nearly half of the biopsy-proven lupus nephritis cases in this study were patients with newly diagnosed SLE. Patients with previously diagnosed SLE and newly diagnosed SLE by kidney biopsy had clinical differences.