Correlation of Anti-Nuclear Antibody Productions With Activity and Chronicity Indexes in Lupus Nephritis: Experience at Urban-Based Tertiary Medical Center.

BACKGROUND

Lupus nephritis (LN) is a frequent and severe complication of systemic lupus erythematosus (SLE) that often necessitates invasive biopsy for definitive management.

OBJECTIVES

To evaluate the association between antinuclear antibody (ANA) titers, specific immunological markers, and LN pathological indexes (activity and chronicity).

DESIGN

A retrospective observational study utilizing cross-sectional comparisons and longitudinal paired-data analysis.

METHODS

We analyzed 159 patients with biopsy-proven LN at an urban tertiary center (2012-2022). Two distinct analyses were performed: (1) a cross-sectional comparison between baseline SLE and LN onset, and (2) a paired longitudinal analysis of 81 individuals with available data at both time points.

RESULTS

ANA titers remained stable between baseline SLE and LN onset (p > 0.05). However, paired analysis revealed significant anti-Smith (anti-Sm) seroconversion at LN onset (p < 0.01). High-intensity direct Coombs' tests (3+) were significantly more prevalent at LN onset (36.4% vs. 5.6%, p = 0.009). In multivariable analysis, serum creatinine was the primary factor associated with LN presentation (OR = 2.138, 95% CI 1.099-4.161, p = 0.025).

CONCLUSION

While ANA titers are stable markers of SLE, they do not dynamically reflect the transition to LN. Instead, anti-Sm seroconversion and serum creatinine levels serve as more relevant markers of clinical transition.