This shift in perspective is gaining momentum within the otolaryngology community, fueled by growing evidence that PID may be responsible for up to a quarter of refractory CRS cases. The realization is prompting a call for increased vigilance and a more proactive approach to identifying these immune system disorders, which ENT specialists are uniquely positioned to detect and manage.
"In the past few years, I have come to realize that in many of my refractory CRS patients, the lack of response is not because the surgery went wrong; it’s because there’s something that is not allowing their innate immunity to fight the problem that led to the surgery," explained Jay Shah, MD, FAAP, FACS, medical director of the pediatric aerodigestive program at University Hospitals of Cleveland Medical Center/Rainbow Babies and Children’s Hospital and associate professor of otolaryngology–head and neck surgery at Case Western Reserve University School of Medicine. Dr. Shah presented an overview of PID as a possible cause of CRS at the Immunoglobulin National Society’s (IgNS) most recent National Conference in Arlington, Texas, highlighting the critical need for ENT physicians to incorporate this awareness into their clinical practice.
The diagnostic journey for many patients with PID can be lengthy and fraught with frustration. According to the Immunoglobulin National Society (IgNS), adults with common variable immunodeficiency (CVID) and related antibody deficiencies often spend 10 to 15 years seeking an explanation for their recurrent infections. During this "diagnostic odyssey," they may endure repeated antibiotic courses, undergo multiple sinus or ear surgeries, and cycle through escalating therapies without a fundamental question being asked: "Why does this patient keep getting sick?" This diagnostic gap has prompted IgNS to launch "Think PI," an educational initiative designed to equip specialists outside of immunology, including otolaryngologists and pulmonologists, with the tools to recognize when recurrent infections might signal an underlying immune disorder.
"The specialists who are most likely to identify these patients first are often not immunologists," stated Amy E. Clarke, DNP, RN, IgCN, chief clinical officer of IgNS. "Think PI is designed to help those frontline specialists recognize when recurrent infections should prompt an immune evaluation." The program’s development involved multidisciplinary advisory boards comprising experts in otolaryngology, pulmonology, and clinical immunology, who identified common barriers to earlier diagnosis, such as a lack of clear thresholds for investigating immune dysfunction, an underestimation of the complexity of initial workups, and a tendency to view recurrent infections as "normal" in otherwise healthy adults.
Red Flags for Primary Immunodeficiency in CRS Patients
A crucial aspect of improving diagnostic timelines involves identifying specific warning signs that can alert ENT physicians to the possibility of an underlying PID. Dr. Shah emphasized the importance of cultivating both curiosity and self-awareness during CRS evaluations. "Sometimes we have to be humble and ask, why did it fail? Was it surgical or was there something else?" he noted, particularly in cases where endoscopic sinus surgery has not yielded the expected results.
Beyond the sinonasal cavity, a constellation of symptoms can point towards a compromised immune system. These red flags, as outlined by Dr. Shah, include:
- Recurrent Sinusitis: More than four episodes per year, particularly those that are severe or prolonged.
- Recurrent Pneumonia: Frequent lung infections, especially those that are difficult to clear or recur in the same location.
- Chronic Diarrhea: Persistent gastrointestinal issues, often associated with malabsorption.
- Recurrent Ear Infections: Persistent or frequent otitis media.
- Recurrent Oral or Skin Abscesses: Frequent localized infections.
- Persistent Oral Ulcers or Thrush: Oral candidiasis that is difficult to treat.
- Family History of Immune Deficiency: A known history of similar conditions within the family.
- Failure to Thrive or Poor Growth: In pediatric patients, a lack of expected growth and development.
Additionally, Dr. Shah highlighted other significant indicators such as chronic or recurrent pneumonia, bronchiectasis, and obstructive pulmonary disease. An increased frequency of chest infections, meningitis, and/or sepsis, alongside gastrointestinal and cutaneous infections, should also raise suspicion for an underlying immune dysfunction.
Diagnostic Pathways: The Role of Vaccine Titers and Immunoglobulin Levels
Distinguishing between a patient who is simply "under-immunized" and one with a true PID often hinges on targeted immunological testing. One practical and widely recommended strategy involves the use of the Pneumovax 23 (PPSV23) vaccine, a polysaccharide vaccine that protects against 23 strains of Streptococcus pneumoniae.
"If they get this Pneumovax booster, which is a polysaccharide vaccine that tests the immune system’s ability to produce immunoglobulins, and you check their antibody titers and their titers go roughly from 0.1 to 7.20, then you know their response to earlier vaccinations, typically with pneumococcal conjugate vaccine [PCV], waned," Dr. Shah explained. In such cases, "they just needed that PPSV23 booster to rebuild their immunity and break the cycle of recurrent infections."
However, if antibody titers remain low following the PPSV23 challenge, "that is a huge red flag that they have PID, and your next step will likely need to be a consultation with an immunologist," he advised.
A 2023 study published in the Annals of Otology, Rhinology & Laryngology by Bonaventure et al. further underscored the utility of the PPSV booster in assessing immune function in CRS patients. The study analyzed 242 patients (ages 0 to 21) diagnosed with recurrent acute otitis media, chronic rhinitis, and chronic otitis media with effusion who had completed the standard four-dose PCV schedule. Initial testing revealed that only 27% of these patients had antibody titers indicating immunity from their prior PCV vaccinations. Following revaccination with PPSV in approximately 85 patients, antibody responses conferring immunity reached 91.8%. "That 10% of remaining nonresponders are the ones you have to worry about," Dr. Shah reiterated. "Those are the patients who may benefit from immunologic evaluation and targeted immunotherapy rather than repeated courses of antibiotics or additional sinus surgery."
For ENT physicians practicing in tertiary care centers, where patients are often referred after multiple treatment failures, this 10% figure might appear deceptively low. Dr. Shah noted that "almost every week, I have a parent come with this typical but incredibly frustrating story of failed interventions." He described successful collaborations with immunology departments, where PID is identified, patients receive immunoglobulin (Ig) therapy, and significant improvements are observed, effectively breaking the cycle of failed surgical and antibiotic interventions.
Initiating Immunologic Workup in the ENT Practice
While access to immunologists may vary, particularly in community settings, ENT physicians can initiate crucial immunologic workups themselves. Chadi A. Makary, MD, MSc, FARS, FACS, chief of rhinology and endoscopic skull base surgery at West Virginia University, advocates for a pragmatic approach. "If we do the initial panel and interpretation, we may not need to send everyone to an immunologist," he stated, highlighting the significant advantage this offers for practitioners not based in large academic or tertiary care centers. Dr. Makary co-authored two recent evidence-based reviews on managing CRS patients with PID in both children and adults.
Dr. Makary recommends a foundational panel of tests that ENT physicians can order, including a complete blood count (CBC) with differential and quantitative serum immunoglobulin levels (IgG, IgA, and IgM). Assessment of functional antibody responses, particularly pneumococcal vaccine titers, is also a key component. "Depending on the clinical scenario, additional testing such as tetanus antibody titers, lymphocyte subsets, or complement studies may be appropriate, but these are often best guided by an immunologist," he added.
The ultimate goal, Dr. Makary stressed, is not merely to identify abnormal lab values but to determine if a patient has a clinically significant immune deficiency that warrants treatment. Immunologists possess the expertise to conduct more comprehensive testing, interpret complex results, assess vaccine responses, and determine the necessity of therapies like immunoglobulin replacement.
The Evidence for Immunoglobulin Therapy in CRS
The efficacy of immunoglobulin (Ig) therapy in patients with CRS and immune dysfunction remains an area of ongoing research and discussion. Dr. Makary and his colleagues meticulously reviewed the existing literature for their evidence-based reviews, finding mixed results.
On the positive side, one study included in their review examined 58 patients with CRS and primary antibody deficiency (PAD) who received Ig replacement therapy. The findings indicated that 58.6% of these patients experienced no acute infections during a 4.2-year follow-up period.
However, contrasting findings emerged from other studies. A study of 22 patients with immunoglobulin deficiency and resistant CRS by May et al. reported that all patients failed intravenous immunoglobulin (IVIG) therapy and subsequently required surgery. Similarly, a study by Quinti et al. involving 224 patients with common variable immunodeficiency (CVID), one of the larger trials in the review, yielded mixed results. While IVIG significantly reduced the incidence of acute infections like pneumonia and otitis, the investigators observed a progressive increase in the development of chronic rhinosinusitis and lung disease among CVID patients across all age groups.
Despite these mixed findings, Dr. Makary and his co-authors concluded that the overall efficacy and safety data for Ig therapy in their evidence-based review were compelling enough to warrant a "preponderance of benefit over harm" assessment. They recommended that Ig treatments should be considered "an option" for patients with CRS and immune dysfunction.
The Significant Cost of a Missed PID Diagnosis
The implications of failing to identify and manage PID in CRS patients are substantial, extending beyond the immediate suffering of the individual. "You also have to consider the striking cost of missing PID in these patients or not managing it effectively," Dr. Makary emphasized. Patients may spend years cycling through repeated antibiotic courses, corticosteroids, imaging studies, office visits, and multiple surgical procedures while the underlying immune defect remains unaddressed.
During this protracted period, ongoing inflammation can lead to irreversible mucosal remodeling and progressive upper and lower airway damage. While surgery can alleviate symptoms and facilitate topical therapies, "it cannot correct the immune deficiency itself," Dr. Makary pointed out. Consequently, "disease recurrence remains common if the immunologic disorder is left untreated."
The cumulative healthcare burden associated with this diagnostic delay can be immense. Beyond the repeated antibiotic exposures and imaging, patients often incur significant costs from emergency department visits, hospitalizations, and multiple surgical interventions.
When asked about the single most important improvement ENT physicians can make in managing these refractory CRS patients, Dr. Makary’s response was unequivocal: "test more for immune deficiency." He described the baseline assays as "relatively simple, quick lab tests" that can uncover abnormalities that, when properly identified and managed, "can make a huge difference in these patients’ lives."
Practical Steps for ENT Physicians
To facilitate the identification of PID in patients with refractory CRS, experts recommend a systematic approach. Aaron N. Pearlman, MD, FACS, associate professor of clinical otorhinolaryngology at Weill Cornell Medical College, agrees that ENT physicians are well-equipped to order and interpret initial immune function tests. He suggests starting with Pneumovax 23 (PPSV23) titers as a highly effective initial screening tool. If titers are high, it indicates adequate immunity. If they are low, a booster response can reveal whether the patient was simply under-immunized.
"For patients who fail to respond to the PPSV23 booster, that’s when I start suspecting immune dysfunction and order follow-up tests," Dr. Pearlman stated. His typical next step involves quantitative immunoglobulins (IgG, IgA, IgM) to assess overall antibody levels.
Measuring a patient’s response to the Haemophilus influenzae type b (HiB) vaccine is also important, as H. influenzae is a common cause of recurrent sinus infections. However, Dr. Pearlman noted a potential challenge: "most adult primary care physicians don’t have this vaccine to boost, since it’s usually done in a pediatric setting." This can lead to gaps in follow-up. To address this, Dr. Pearlman has implemented workflow processes to ensure patients receive the booster and have their titers retested. "It can’t all be on the patient. Because if the testing process breaks down, all of your initial interventions and workups have gone for naught," he stressed.
Dr. Pearlman’s research, including a 2020 study in the American Journal of Rhinology & Allergy, explored the prevalence of abnormal immunologic test results in pediatric patients with CRS or recurrent acute rhinosinusitis. The study found that IgM deficiencies were the most common (13%), followed by IgA (11.1%). Additionally, a significant percentage of patients had insufficient protective titers to polysaccharide vaccines (55%) and HiB titers (30%). Based on these findings, Dr. Pearlman recommends that high-yield testing in children with recurrent sinus disease should include titers to polysaccharide antigens like Strep pneumo and H. influenzae.
Collaboration and Continued Vigilance
The evolving understanding of CRS emphasizes its nature as an inflammatory condition potentially spurred by immune dysfunction. While some cases may be straightforward enough for an ENT physician to manage independently, particularly those identified as simply under-immunized, Dr. Pearlman advises physicians to be "ready and willing to call for an immunologist consult" when the immunologic picture becomes complex.
He cautioned that not all patients with documented immune dysfunction will respond to treatments like Ig therapy, as the causal relationship between CRS and specific immune deficits is not always absolute. However, in his practice, Dr. Pearlman has witnessed "major improvements after identifying and treating an immunodeficiency," such as a reduction in annual sinus infections from eight to ten down to one or two. He acknowledges that such outcomes are not universal and encourages practitioners to be prepared for varying responses.
Ultimately, managing CRS patients with suspected immune dysfunction requires a commitment beyond a single encounter. Dr. Pearlman underscores the need for ENTs to remain actively involved, whether through ensuring appropriate immune function tests are ordered and results are analyzed by the care team or by seeking immunologist consultations. He warns against complacency, stating, "Don’t be lulled into inattention because these nonresponders represent a small part of your patient base. They need as much—or arguably more—of your attention to break that cycle of repeated sinus disease and failed treatments as your more responsive patients."
The collective insights from these experts signal a critical paradigm shift: for patients with persistent and refractory CRS, the solution may lie not solely within the sinonasal cavity, but within the intricate workings of their immune system. By embracing a more comprehensive diagnostic approach and fostering collaboration with immunologists, ENT physicians can unlock crucial diagnoses and significantly improve the lives of these often-underserved patients.
