Comparison of Clinical Characteristics, Outcomes in IgA Vasculitis and IgA Nephropathy

Shirel Levanon, MD

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Despite presenting multiple similarities in their pathogenesis, IgA vasculitis (IgAV) and IgA nephropathy (IgAN) have distinct clinical manifestations and long-term outcomes, as highlighted in a retrospective study conducted at rheumatology and pediatric departments at a medical center in Israel.

Adult patients with IgAV went on dialysis sooner and had shorter survival time than those with IgAN, although these differences did not reach statistical significance – still, these findings highlight the high risk of progression to persistent renal impairment in this patient population.¹

“Although the comprehensive pathogenesis of IgAV with nephritis has not been fully elucidated, it shares cardinal features with IgAN,” wrote investigators.^{1 "}Due to their similarities, IgAV and IgAN considered to be 2 manifestations of the same entity, however the multi-system involvement in IgAV implies that they might have different underlying origins.”

A form of blood vessel swelling affecting capillaries in the skin and kidneys, IgAV is rare and most commonly affects children but can also present in adults and cause severe kidney damage. Many researchers have speculated IgAV could be a systemic form of IgAN due to their similar pathophysiological mechanisms. However, this hypothesis has not been confirmed as clinical studies comparing the conditions are few and far between.^2,3

To examine and compare clinical characteristics and long-term renal outcomes in adult-onset IgAV, childhood IgAV, and non-vasculitic IgAN, Shirel Levanon, MD, of the department of rheumatology at Emek Medical Center in Israel, and colleagues retrospectively collected data for children and adults with IgAV and IgAN admitted to the Rheumatology and Pediatric departments at Ha’Emek Medical Center and Rambam Health Care Campus from 2007–2019.¹

Investigators required a confirmed skin biopsy interpreted by an expert skin pathologist for adult IgAV patients. In the pediatric IgAV group, patients’ diagnosis was obtained by a pediatric rheumatologist or an expert pediatrician and no skin biopsy was required. The diagnosis of IgAN required a kidney biopsy showing mesangial IgA deposition and an expert nephrologist diagnosis.¹

A total of 60 adult IgAV, 60 pediatric IgAV, and 45 IgAN patients were included in the study. Investigators compared frequencies of clinical manifestations, laboratory findings, treatments, and long-term outcomes at 1-year follow-up, including all-cause mortality and dialysis.¹

The adult IgAV group was significantly older than the IgAN group (53.1 years vs 45.1 years; P = .02) but had fewer male patients (41.7%) than the IgAN (77.8%) and pediatric IgAV (55%) groups (P = .001).¹

Investigators additionally pointed out adult-onset IgAV patients had higher rates of preexisting comorbidities while a history of preceding infection was more prevalent among pediatric-onset IgAV patients (44.8%) compared to the adult IgAV (20.0%) and IgAN (13.6%) (P = .001).¹

At 1 year of follow-up, 6 IgAN patients and 8 adult-onset IgAV patients required dialysis. During long-term follow-up, 9 adult-onset IgAV patients and 10 IgAN patients required dialysis. The mean time to dialysis was 11.1 years for adults with IgAV (95% Confidence interval [CI], 9.8–12.4 years) and 5.8 years for adults with IgAN (95% CI, 5.0–6.6 years), with no statistically significant difference observed between the 2 groups (Mantel-Cox χ2, 0.69; P >.41). Investigators noted no pediatric patient with IgAV underwent dialysis throughout this time.¹

Overall mortality at long-term follow-up was greater in the IgAV adult group (n = 14) compared to the IgAN group (n = 3). The leading causes of death among the adult IgAV group were cardiovascular diseases, sepsis, and cancer.¹

After excluding an outlier from adult-onset IgAV group, investigators noted patients from this group had significantly shorter survival time (5.5 years; 95% CI, 4.8–6.2 years) compared to their IgAN counterparts (7.0 years; 95% CI, 6.6–7.5 years; log-rank χ2, 6.14; P <.01). However, after controlling for age, sex, hypertension, IHD, BMI, obesity, diabetes, dyslipidemia, and CKD, this difference was no longer statistically significant.¹

“Although IgAV tends to be a self-limited disease, IgAV in adults presents substantial clinical manifestations, typically high risk of progression to persistent renal impairment. Since the treatment options are not well agreed upon, we think that further studies and collaboration should be taken to guide clinicians for the best therapeutic management,” investigators concluded.¹

References:

1. Levanon S, Gotloib V, Kraus Y, et al. IgA vasculitis in adults, pediatrics and non-vasculitic IgA nephropathy, retrospective analysis from 2 centers. Medicine 102(50):p e36521. doi:10.1097/MD.0000000000036521
2. NIDDK. IgA Vasculitis. Kidney Disease. April 20, 2020. Accessed January 11, 2024. https://www.niddk.nih.gov/health-information/kidney-disease/iga-vasculitis
3. Pillebout E. IgA Vasculitis and IgA Nephropathy: Same Disease?. J Clin Med. 2021;10(11):2310. Published 2021 May 25. doi:10.3390/jcm10112310