Three main warning signs may help identify children with underlying primary immunodeficiency diseases (PID), according to the results of a retrospective survey reported online April 11 and appears in the May print issue of Pediatrics.

"Children with severe, recurrent, or unusual infections may have an underlying ...PID," write Anbezhil Subbarayan, MBBS, from the Department of Paediatric Allergy and Immunology, University of Manchester, Royal Manchester Children's Hospital in Manchester, United Kingdom, and colleagues. "Ten warning signs have been promoted by patient support groups to help identify children with PID, but the signs have never been tested in a rigorous scientific study."

The objective of the study was to examine the efficacy of these ten warning signs in the prediction of defined PID among 563 children evaluated at two tertiary PID centers in northern England. Medical records were reviewed for 430 children with a defined PID and 133 children for whom thorough workup did not result in a diagnosis of a specific PID.

Hospital clinicians referred 96% of the children with PID. Factors most predictive of PID were a family history of immunodeficiency disease, as well as sepsis treated with intravenous antibiotics in patients with neutrophil PID, and failure to thrive in children with T-lymphocyte PID. When these three signs were present, PID was correctly identified in 96% of patients with neutrophil and complement deficiencies and in 89% of children with T-lymphocyte immunodeficiencies. The only warning sign that correctly identified patients with B-lymphocyte PID was a positive family history.

"PID awareness initiatives should be targeted at hospital pediatricians and families with a history of PID rather than the general public," the study authors write. "Our results provide the general pediatrician with a simple refinement of 10 warning signs for identifying children with underlying immunodeficiency diseases."

Limitations of this study include retrospective design and reliance on medical records. In addition, at least 4% of children with PID would be missed even if the recommendations made in this study were followed.

"Delayed diagnosis of PID may be associated with increased morbidity and mortality," the study authors conclude. "In children presenting with infection, pediatricians should always inquire about a family history of PID, as this is the best predictor that the patient may also have an underlying immunodeficiency....In those with recurrent or severe infections, clinical features other than family history are often not helpful and a lower threshold is required for requesting antibody testing in which the diagnosis of a B-cell immunodeficiency is suspected."

The study authors have disclosed no relevant financial relationships.

Pediatrics. Published online April 11, 2011.

Laurie Barclay, MD • Medscape Medical News © 2011 WebMD, LLC