POS1130 DELAYED LUPUS LOW DISEASE ACTIVITY STATE ENTRY IN LUPUS NEPHRITIS: ITS ASSOCIATION WITH POORER RENAL OUTCOMES AND ROLE IN RELAPSE PREDICTION
Authors: C. K. Cheung, C. S. Lau, S. C. W. Chan
Journal: Annals of the Rheumatic Diseases (2024)

<h3>Background:</h3> Lupus nephritis (LN) is a common yet severe comorbidity affecting patients with systemic lupus erythematosus (SLE). Lupus low disease activity state (LLDAS) is a validated treat-to-target approach in SLE patients. A shorter time to reach LLDAS has known favourable outcomes among SLE patients, but the exact role among LN patients has been uncertain. There is also a lack of a simple validated clinical tool to predict future relapse among patients with LN. <h3>Objectives:</h3> This study investigates the renal and extra-renal prognosis with delayed LLDAS entry, as well as its potential role as a clinical predictor of LN relapse. <h3>Methods:</h3> Patients with biopsy-proven LN in 2010-2020 were included; those unable to reach LLDAS by the end of the follow-up period were excluded. They were routinely followed up to repeat blood tests and urinalysis. After the index LN, their date to first reach LLDAS was documented to calculate time-to-LLDAS. Any subsequent relapse was documented. CKD stages were determined by eGFR calculated using the abbreviated Modification of Diet in Renal Disease (MDRD) formula. The Systemic Lupus International Collaborating Clinics/American College of Rheumatology (SLICC/ACR) Damage Index (SDI) at baseline and the end of follow-up were compared to evaluate the damaged accruals. LN relapse was defined as a rebiopsy-proven LN after the initial treatment response of a 50% proteinuria reduction under the nephrotic range. Time-to-event analysis were conducted to evaluate their association with time-to-LLDAS. Receiver operating characteristic (ROC) curve with area under curve (AUC) for time-to-LLDAS was plotted. <h3>Results:</h3> 159 patients were included in this study. 145 (92%) patients were female. Most patients (72%) had pure or mixed class III/IV LN. The median follow-up duration was 9.5 years, with interquartile range (IQR) of 4.2 years. Patients with poorer outcomes required a significantly longer duration to reach LLDAS. These events include relapse and a higher CKD stage, such as CKD &gt; stage 3 (Table 1). For every additional year delay in first attaining LLDAS, the relative hazard of relapse increased by 36%, hazard ratio (HR) = 1.36 (95% Confidence Interval = 1.14-1.61, <i>p</i> &lt; 0.001). Delayed LLDAS attainment was also associated with increased damaged accrual captured by SDI. SDI increased by 0.20 per every year delay in reaching LLDAS (<i>p</i> &lt; 0.001). Among class III/IV LN patients, time-to-LLDAS showed an AUC of 0.72 in the ROC curve (Figure 1). As the AUC &gt; 70%, time-to-LLDAS was an acceptable predictive test of relapse. When the cutoff was set to 12 months, the sensitivity and specificity were 71% and 65% respectively in this subgroup. <h3>Conclusion:</h3> Prolonged time to reach LLDAS after LN may be associated with a poorer prognosis. Time-to-LLDAS may also be a viable tool in predicting relapse among patients with class III/IV LN. <h3>REFERENCES:</h3> <b>NIL.</b> <h3>Acknowledgements:</h3> <b>NIL.</b> <h3>Disclosure of Interests:</h3> <b>None declared.</b>