Interferon-α as a biomarker to predict renal outcomes in lupus nephritis.

Objective: To determine if serum interferon (IFN)-α levels at the time of a lupus nephritis (LN) flare are associated with renal outcomes.

Methods: Patients with an LN flare who had a preflare estimated glomerular filtration rate (eGFR) ≥60 mL/min were included in the study. The following outcomes were ascertained: (1) Time to first and second LN flares during follow-up, (2) Time to a sustained decline in eGFR by 30% and 50%, and progression to end-stage renal disease (ESRD, <15 mL/min), and (3) Time to an adverse renal event (≥2 renal flares and/or at least a 30% sustained decline in eGFR during follow-up). Serum IFN-α was measured by Simoa.

Results: 92 patients with active LN were included in the study. Elevated serum baseline levels of IFN-α predicted poor renal outcomes. Patients with higher baseline IFN-α had a greater risk of having two or more subsequent LN flares (HR: 1.31 (1.08-1.59), p=0.006), sustained 30% decline in eGFR (HR: 1.27 (1.14-1.40), p<0.001), 50% decline in eGFR (HR: 1.27 (1.12-1.33), p<0.001) and progressing to ESRD (HR: 1.29 (1.14-1.47), p<0.001). Receiver operating characteristic analysis identified an IFN-α cut-off, 0.6 pg/ml, for predicting an adverse renal event.

Conclusions: Elevated serum IFN-α levels measured at the time of an LN flare are associated with poor renal outcomes, including the development of ≥2 LN flares, and a clinically meaningful decline in kidney function.