MPA most common AAV type in girls, Hispanic children in California

Children with MPA seem to need more intensive care, dialysis, small study finds

Margarida Maia, PhD avatar

by Margarida Maia, PhD |

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Microscopic polyangiitis (MPA) was the most common type of ANCA-associated vasculitis (AAV) among girls and Hispanic children in a California tertiary care hospital, a small study has found.

While time to diagnosis was shorter, children with the disorder seemed to need more intensive care and dialysis, a treatment that filters blood to remove wastes and extra water when the kidneys fail to do so.

The study, “Childhood-Onset ANCA- Associated Vasculitis: single center experience from Central California,” was conducted by investigators at Valley Children’s Healthcare in Madera, California, and published in Pediatric Rheumatology.

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Though rare, AAV symptoms can appear in childhood

AAV occurs when the immune system attacks the small blood vessels in the body by mistake, causing them to become inflamed and damaged. Although rare, symptoms of AAV can appear during childhood.

However, information about childhood-onset AAV mostly comes from studies done in Europe and North America, where the majority of the patients are white.

“Gaining an understanding of disease presentation and complications of pediatric AAV in multiethnic populations may help identify gaps in the evaluation and treatment of children with AAV,” the researchers wrote.

To learn about how the disease manifests in children living in Central California, the researchers searched the medical records at Valley Children’s Healthcare for cases of childhood-onset AAV.

They identified 21 children (15 girls, six boys) who received their diagnosis of AAV between 2010 and 2021, at a median age of 14 years. Nine (43%) were Hispanic, nine (43%) were white, two (9%) were Asian, and one (5%) had multiracial ancestry.

Gaining an understanding of disease presentation and complications of pediatric AAV in multiethnic populations may help identify gaps in the evaluation and treatment of children with AAV.

More common for girls to have MPA than GPA

Twelve (57%) had MPA and nine (43%) had granulomatosis with polyangiitis (GPA), the two most common types of AAV. It was more than twice as common for girls to have MPA than GPA (92% vs. 44%).

About two-thirds (67%) of children with MPA were Hispanic, whereas most (78%) of those with GPA were white. The median duration of symptoms prior to diagnosis was shorter for MPA than for GPA (14 vs. 21 days).

All children experienced fatigue, a general feeling of discomfort, fever, and weight loss. Most (90%) had signs of kidney involvement, including blood in their urine (hematuria), too much protein in their urine (proteinuria), and high blood pressure.

Lung involvement also was common (76%), and ear, nose, and throat involvement was much more frequent in children with MPA than in those with GPA (89% vs. 8%).

In AAV, the attack launched against small blood vessels is triggered by self-reactive antibodies called ANCAs. Its main targets are myeloperoxidase (MPO) and proteinase 3 (PR3), two proteins found in neutrophils, a type of immune cell involved in the attack.

All children tested positive for ANCAs. Anti-MPO antibodies were more common in children with MPA than in those with GPA (83% vs. 22%), whereas anti-PR3 antibodies were more common in the GPA group (100% vs. 8%).

Notably, all Hispanic children tested positive for anti-MPO antibodies. Eight (89%) out of the nine white children tested positive for anti-PR3 antibodies.

The proportion of children admitted to the intensive care unit was about twice as high in children with MPA as in those with GPA, but the difference was not significant (67% vs. 33%). Of the nine children who required dialysis, six had a diagnosis of MPA.

Two children with MPA died. One had severe lung involvement and died of Aspergillus pneumonia, an infection of the lungs caused by Aspergillus fungi, and sepsis — an extreme reaction to an infection that causes organs to fail. The other child had an initial presentation that included coughing up blood from the lungs and end-stage renal disease.

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Methylprednisolone used to induce remission in all the children

Intravenous (into-the-vein) methylprednisolone, a glucocorticoid, was used to induce disease remission, where no symptoms appear for a time, in all children. It was used in combination with the immunosuppressant cyclophosphamide or rituximab, or both.

Five (42%) of the children with MPA received methylprednisolone in combination with cyclophosphamide, and another five (42%) in combination with rituximab.

Children with GPA most commonly received methylprednisolone in combination with cyclophosphamide (78%).

Five children (three with MPA and two with GPA) also underwent plasmapheresis, a blood-cleaning procedure that removes disease-causing antibodies from circulation.

“Given the paucity of data from our geographic area and sparse literature in pediatric patients from racial and ethnic minority backgrounds, this study provides a unique understanding of characteristics of pediatric AAV,” the researchers concluded.