SII and SIRI as Prognostic Biomarkers in Lupus Nephritis

Emerging Inflammatory Biomarkers (SII and SIRI) for Predicting Disease Activity, Renal Flares and Outcomes in Lupus Nephritis: A Prospective Observational Study

This prospective observational study aims to evaluate the prognostic utility of the Systemic Immune-Inflammation Index (SII) and Systemic Inflammation Response Index (SIRI) as novel inflammatory biomarkers for monitoring disease activity and predicting renal progression, flares, and outcomes in patients with lupus nephritis.

Lupus nephritis (LN) is a common and serious manifestation of systemic lupus erythematosus (SLE) that can lead to progressive renal damage and end-stage renal disease. Current assessment of disease activity and prognosis relies mainly on proteinuria, serum creatinine, estimated glomerular filtration rate (eGFR), and kidney biopsy, which is invasive and not always feasible for repeated monitoring.

Simple blood count-derived inflammatory indices, such as the Systemic Immune-Inflammation Index (SII) and the Systemic Inflammation Response Index (SIRI), have recently emerged as potential biomarkers of systemic inflammation. These indices are inexpensive, readily available, and may reflect disease activity and renal risk in lupus nephritis. However, their prognostic value remains incompletely established, particularly in prospective settings.

This prospective observational study will evaluate the ability of SII and SIRI to monitor disease activity and predict renal flares and outcomes in patients with lupus nephritis over a 12-month follow-up period.

Inclusion Criteria:

• Age ≥ 18 years
• Diagnosis of systemic lupus erythematosus according to the 2019 EULAR/ACR classification criteria
• Confirmed lupus nephritis according to ISN/RPS classification

Exclusion Criteria:

• Active infection, sepsis, or other concurrent inflammatory or autoimmune conditions
• Malignancy or hematologic disorders affecting blood cell counts
• Pregnancy
• Use of medications significantly affecting blood counts (such as recent chemotherapy or G-CSF)
• Incomplete medical records or anticipated loss to follow-up