Background/Purpose: IgA Vasculitis (IgAV) is a systemic small vessel vasculitis that affects the skin, joints, gastrointestinal tract, and kidneys. While most common in children, it is rare in adults and associated with worse prognosis. IgAV has a variable course with many patients spontaneously entering remission, making it difficult to know which patients need treatment.

A few retrospective trials have shown that adult IgAV patients with greater proteinuria, kidney insufficiency at time of biopsy, and hypertension have worse overall prognosis, often developing progressive kidney disease. Retrospective studies in European and Asian populations have also considered the MEST-C renal biopsy score components as predictive tools in IgAV.

The goal of this study is to expand on existing studies and identify clinical factors that predict poor outcome in IgAV adults. We also aim to identify histologic prognostic factors using the MEST-C score components. Identifying prognostic factors will improve patient treatment plans while informing future therapeutic studies.

Methods: We conducted a retrospective analysis of 31 IgAV adult patients. A Cohort Discovery Tool was built to identify eligible patients. The primary outcome was progressive kidney disease, defined as nephrotic range proteinuria ( > 3.5g/d) or > 30% creatinine elevation within 1 year of kidney biopsy.

We included patients age > 18, with at least one symptom of IgA Vasculitis (cutaneous palpable purpura, arthritis, bowel angina), and kidney biopsy consistent with IgAV.

We collected data on patient’s kidney function at time of diagnosis, and at 3, 6, and 12 month intervals. For preliminary analyses, we assessed Pearson correlation of clinical factors and MEST-C components with the primary outcome.

Results: Baseline creatinine was shown to have significant correlation with renal progression at 1 year, yielding a Pearson coefficient of .887 (2-tailed significance < .001, n = 21). Age, systolic blood pressure, and degree of proteinuria did not have significant Pearson coefficients at 3, 6, or 12 month intervals.

The “E” component in MEST-C, which stands for Endocapillary Hypercellularity, also showed significant correlation with renal progression at 1 year, with a Pearson coefficient of .776 (2-tailed significance < .001, n = 26). Other components of the MEST-C score did not yield significant correlations

Conclusion: Similar to existing studies, renal insufficiency at baseline is a prognostic indicator of poor outcomes in IgA Vasculitis patients. Age, initial proteinuria, and hypertension were not correlated with kidney progression in our study, which diverges from prior literature. Regarding histologic predictive factors, the “E” in MEST-C (Endocapillary Hypercellularity) is predictive of renal progression in prior studies, and we were able to validate this finding. Next steps in our study include expanding our cohort, as well as correlating treatment regimens with renal progression at 1 year.

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ACR Meeting Abstracts - https://acrabstracts.org/abstract/clinical-and-histologic-prognostic-factors-of-renal-progression-in-adults-with-iga-vasculitis/