Supplemental Material for: The clinical and pathological significance of CD9 in IgA nephropathy with crescent lesions

We conducted a retrospective cohort study of 47 IgAN patients and analyzed clinical, pathological, and prognostic data. Renal biopsy specimens were immunostained for CD9. The primary endpoint was a ≥15% decline in estimated glomerular filtration rate (eGFR), and the secondary endpoint was 24‑hour proteinuria ≥3.5 g/d.

Receiver operating characteristic (ROC) curve analysis, Kaplan‑Meier survival analysis, and Cox proportional hazards regression were performed to evaluate the diagnostic and prognostic value of CD9.</p><p dir="ltr">Results: ROC curve analysis showed that CD9 had significant diagnostic value for identifying crescent lesions in IgAN patients (sensitivity 85.7%, specificity 75.0%, p < 0.001). Kaplan‑Meier analysis indicated that higher CD9 expression and crescent proportions of <10% or ≥25% were associated with lower renal survival rates.

In multivariable Cox analysis, after adjusting for crescents ≥25%, baseline eGFR, proteinuria, and immunosuppressive therapy, CD9 expression level remained an independent predictor of the primary endpoint (HR 16.45, 95% CI 3.83–70.97; p < 0.001).</p><p dir="ltr">Conclusions: CD9 demonstrates significant diagnostic value for identifying crescent lesions in IgAN patients and serves as an independent predictor of eGFR decline.

Assessed on renal biopsy tissue, CD9 may be a potential adjunct marker for risk stratification in IgAN patients with crescent lesions.</p>