[Histopathological findings associated with complete clinical remission in patients with lupus nephritis]

Lupus nephritis (LN) is a serious manifestation of systemic lupus erythematosus. Patients who do not achieve remission have a 10-year renal survival rate of 19%.

To evaluate the histopathological findings of LN associated with complete remission > 12 months after kidney biopsy.

Retrospective cohort of adults with lupus (2019 EULAR/ACR criteria) who underwent kidney biopsy between January 2017 and December 2021. Clinical, biochemical, and histopathological data were collected at the time of biopsy; renal function (serum creatinine, estimated glomerular filtration rate [eGFR], and proteinuria/day) was measured throughout the study (end of follow-up in June 2023).

Thirty-eight patients were included. When comparing the non-remission group (n = 13) with the complete remission group (n = 18), only the degree of interstitial fibrosis and tubular atrophy (IFTA) (grade 2: 46% vs. 11%, respectively) and the chronicity index [5.0 (4.0-6.5) vs. 3.0 (1.0-5.0)] showed significant differences (p < 0.05). At the end of the study, the non-remission group, compared with the complete remission group, had lower eGFR [57 (10-100) vs. 104 (87-123) mL/min/1.73 m², p < 0.05] and higher proteinuria [4.00 (1.82-8.00) vs. 0.25 (0.16-0.39) g/day, p < 0.05]. In the logistic regression analysis, only proteinuria [OR 0.72 (95%CI 0.54-0.98), p = 0.03] predicted remission.

The histopathological findings associated with complete LN remission > 12 months were lower IFTA and a lower chronicity index. In the multivariate analysis, the only significant variable predicting remission was baseline proteinuria.