SAN DIEGO – Using chronic sinusitis patients’ response to Pneumovax to screen them for specific antibody deficiency may lead to overtreatment with intravenous immunoglobulin, a study showed.
In addition to its traditional use to prevent pneumonia and other infections, Pneumovax (pneumococcal vaccine polyvalent) has found a new role recently: as a screening tool in chronic rhinosinusitis (CRS) patients for specific antibody deficiency (SAD), a type of immune deficiency. If patients have a poor antibody response to the Pneumovax shot, they are thought to have SAD and are placed on intravenous immunoglobulin (IVIG) – sometimes without much regard for their clinical history. The practice has been fueled by the growing suspicion that chronic rhinosinusitis might be driven by a faulty immune system.
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Dr. Anjeni Keswani
However, the severity of SAD does not correlate neatly with the response to Pneumovax, Northwestern University investigators found in a study of 595 adult CRS patients. So, treating patients with IVIG based primarily on how they respond to the vaccine might be overkill. To prevent overuse of IVIG, it’s probably best to limit Pneumovax screening to patients with clinically worse disease, according to lead investigator Dr. Anjeni Keswani, formerly of Northwestern University in Chicago but now an allergist/immunologist at Duke University in Durham, N.C.
Overall, the proper role of Pneumovax screening still needs to be worked out. At least for now, SAD "just can’t be a laboratory diagnosis. It should include clinical history before you make a decision on IVIG therapy," Dr. Keswani said.
In the Lund-MacKay staging system for CRS, higher scores mean worse disease. The 95 patients in the study who had mild SAD (defined as 7-9 protective Streptococcus pneumoniae antibody titers after vaccination, out of 14 serotypes measured) and the 120 patients with moderate SAD (3-6 protective titers after vaccination) had significantly higher Lund-MacKay scores than the 24 patients with severe SAD. Severe SAD was defined as 2 or fewer protective titers following the vaccine.
Mild and moderate SAD patients also had significantly higher rates of asthma and higher, although not significantly higher, rates of allergic rhinitis and nasal polyps, Dr. Keswani said at the annual meeting of the American Academy of Allergy, Asthma, and Immunology.
Meanwhile, patients with more severe SAD were significantly more likely than mild SAD patients to have pneumonia histories and, when present, more severe asthma. And they used significantly more antibiotics in the 2 years following vaccination.
Asthma severity, antibiotic use, and pneumonia history in mild SAD patients were, in fact, similar to rates in CRS patients without immune deficiency. That raises the possibility that what’s now considered mild SAD might not even be an immunodeficiency, hence the notion of limiting Pneumovax screening to patients who are worse off.
As it all gets sorted out, "we don’t want patients diagnosed with SAD to automatically be placed on immunoglobulin replacement," Dr. Keswani said. "I don’t think that’s useful for the majority of patients. There is a proportion who mount a good response to infection; they may have an impaired response to the vaccine, but we can manage them with antibiotic prophylaxis and early assessment.
"We are trying to come up with guidelines to better help determine who should be screened," she added. "If they don’t have evidence of infection, I don’t think we can actually call them SAD."
Dr. Keswani said she had no relevant disclosures, and there was no outside funding involved in the project.