From the Journals

IPD in children may be a signal of immunodeficiency



Recurrent invasive pneumococcal disease in children could be a signal of underlying primary immunodeficiency, according to a systematic review published in JAMA Pediatrics.

Coen Butters, BMed, DCH, of the Royal Children’s Hospital in Melbourne, and coauthors wrote that, even with optimal vaccine coverage, there is still a group of children with increased susceptibility to invasive pneumococcal disease (IPD), and this could be a potential marker of primary immunodeficiency.

They conducted a systematic review of 17 studies of 6,002 children to examine the evidence on the incidence of primary immunodeficiency in children who presented with IPD but without any other risk factors or predisposing conditions.

Overall, the frequency of primary immunodeficiency in children presenting with IPD who did not have any other predisposing condition ranged from 1% to 26%.

One study of 162 children with IPD, which had an overall frequency of primary immunodeficiency of 10%, found that children older than 2 years were significantly more likely to have primary immunodeficiency than those aged under 2 years (26% vs. 3%; P less than .001).

Primary antibody deficiency was the most commonly diagnosed immunodeficiency in these children with IPD, accounting for 71% of cases. These deficiencies presented as hypogammaglobulinemia, specific pneumococcal antibody deficiency, X-linked agammaglobulinemia, and IgG2 deficiency.

The review also included four studies that looked at the frequency of mannose-binding lectin deficiency in 1,493 children with primary IPD. Two of these studies reported a prevalence of mannose-binding lectin deficiency ranging from 31% in children aged younger than 2 years to 41% in children younger than 1 year.

Five studies looked at the rate of primary immunodeficiency in children presenting with recurrent IPD. In addition to other predisposing conditions such as sickle cell disease, cancer, and anatomical breach in the blood-brain barrier, the three studies that screened for primary immunodeficiency found rates ranging from 10% to 67%. The most common conditions were complement deficiency, pneumococcal antibody deficiency, and a single case of TLR-signaling defect.

In a study of 162 children with primary IPD, screening for asplenia identified a single case of congenital asplenia. In another study of 2,498 cases of IPD, 22 patients had asplenia at presentation, half of whom died at presentation.

Dr. Butters and associates concluded that “this review’s findings suggests that existing data support the immune evaluation of children older than 2 years without a known predisposing condition who present with their first episode of Streptococcus pneumoniae meningitis, pneumonia, or recurrent IPD. Immune evaluation should include assessment for immunoglobulin deficiency, pneumococcal antibody deficiency, complement disorders, and asplenia.”

In an accompanying editorial, Stephen I. Pelton, MD, of the Maxwell Finland Laboratory for Infectious Diseases at Boston Medical Center, and coauthors wrote that in children with recurrent episodes of IPD caused by nonvaccine serotypes – particularly those aged over 5 years – evaluation for primary immunodeficiencies could uncover immune defects.

“Once identified, direct and indirect protection, penicillin prophylaxis, or a combination of these offers great potential for disease prevention and reduction of mortality and morbidity in children with [primary immunodeficiency],” they wrote.

No funding or conflicts of interest were declared for the study. Two of the editorialists declared research funding or honoraria from the pharmaceutical sector.

SOURCES: Butters C et al. JAMA Pediatr. 2019 Sep 30. doi: 10.1001/jamapediatrics.2019.3203; Pelton SI et al. JAMA Pediatr. 2019 Sep 30. doi: 10.1001/jamapediatrics.2019.3185.

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