Table 1_High complement activation index predicts renal progression in crescentic IgA nephropathy.docx

Individual complement markers show inconsistent prognostic value. We developed a composite Complement Activation Index (CAI) and tested its association with renal progression.</p>Methods<p>This study enrolled 157 biopsy-confirmed patients with crescentic IgAN.

The CAI was derived from four components: (i) urinary C3 > 2.8mg/L, (ii) serum C3 < 0.80 g/L, (iii) glomerular C3 immunofluorescence intensity ≥ 2+, and (iv) presence of glomerular C1q deposition. Each component contributed 1 point, categorizing patients into low- CAI and high- CAI groups. The association between CAI and the composite kidney disease progression event, defined as doubling of serum creatinine or end-stage renal disease, was assessed using Cox proportional hazards models.</p>Results<p>A high CAI (43.9%, 69/157) was associated with worse baseline renal function (eGFR 39 vs. 65 mL/min/1.73 m², P<0.001), higher proteinuria (4.6 vs. 2.3 g, P<0.001), and more advanced tubulointerstitial injury.