Allergic Disease — The Challenge of Recognition and Diagnosis
50 million people in the United States - 1 in 5 Americans – suffer from allergy. It is the 5th leading chronic disease in the U.S. and the 3rd most common disease among children under 18 years old of age.1 Individuals with allergies are at heightened risk for other diseases, including asthma.
Allergic rhinitis is the most commonly diagnosed allergy among adults, while skin allergies and respiratory allergies are those most commonly diagnosed among children.1 The incidence of allergic disease, particularly allergic rhinitis and allergic asthma, is increasing but identifying allergic disease in the primary care setting is a challenge.
Dr. Inderpal Randhawa, Attending Physician, Southern California Allergy, Asthma and Pulmonology Specialists, discusses the nature of these challenges and reviews approaches to help in timely, accurate diagnosis of allergic disease.
The Diagnostic Challenge
“The greatest single challenge in treating allergic based diseases is essentially to make a proper diagnosis,” says Dr. Randhawa. “Unlike with other conditions - for example, chest pain as a symptom of heart attack – these diseases are often not obvious and so are often mistaken for other types of illnesses. If you have nasal congestion or a sore throat,” he explains, “many primary care doctors treat that as an infectious process - a sinus disease, sinusitis, or something of that nature - when it might be allergy. It’s the same thing with chronic cough and with recurrent infections of the lung, each of which are commonly due to untreated allergies, as well as with some skin diseases.”
On the other hand, the term "allergy" is used loosely by the general public. “If a certain exposure results in an itch, a sneeze or a wheeze, the public labels it an allergy,” notes Dr. Randhawa. “This leads to frequent trips to the "allergy" aisle of the drug store only to suffer failed therapy, followed by visits to the primary care provider assuming the issue is atopic. As such, a proper diagnosis of allergy is paramount to any treatment modality.”
Identifying allergic disease early is also important because of allergy’s role as a comorbid condition, notes Dr. Randhawa. “Allergic disease plays a role in everything from asthma and snoring to headaches and migraines. The 2007 National Institutes of Health (NIH) guidelines on asthma shed light on the clear connection between allergic rhinitis and asthma, and how asthma may be difficult or impossible to control without concurrent diagnosis and treatment of hay fever.”2
Steps to Diagnosis
The first step for a primary care doctor trying to diagnose allergic disease is recognition. “You need to recognize who the high risk groups are,” says Dr. Randhawa, “namely patients who have recurrent upper airway and lower airway symptoms that require treatments such as antibiotics, decongestants and occasionally steroids. Those patients need to be worked up as part of a diagnostic strategy.”
“Diagnostic strategy in the primary care world is really limited to blood-based testing,” notes Dr. Randhawa, “as primary care doctors typically aren’t able to perform skin-based tests or other type of allergic tests. For blood-based testing ImmunoCAP® is an excellent choice.”
ImmunoCAP® is an in vitro quantitative assay which measures allergen specific immunoglobulin E (IgE) in human serum. “It’s the test used by most universities and large health systems, because it has excellent sensitivity and specificity, allowing you to be right about 90% of the time. If the test comes back positive you know that person likely has an allergic predisposition and that you might want to target in improving their disease. The utilization of ImmunoCAP® provides the primary care setting the excellent option to make an appropriate diagnosis and commence appropriate therapy.”3
One anticipated development in allergic disease therapy in the United States is the possible FDA approval of sublingual immunotherapy (SLIT) for grass allergens, as an alternative to the standard subcutaneous injection form. While there’s no good head-to-head study to compare the two tests, Dr. Randhawa indicates that they work similarly and that there is longitudinal data to show they induce a similar immune response. “SLIT has been available in Europe for 40 to 50 years, so there is a lot experience with it,” observes Dr. Randhawa. “In fact, there was a recent review in the Journal of the American Medical Association of 63 studies, which showed SLIT to be effective for nasal, ocular and sinus-based allergies and also showed efficacy for asthma.4 SLIT has been shown to relieve symptoms relatively quickly compared to injection: most people on SLIT seem to see improvement at around 8-9 months into therapy, compared with around a year and more for shots.”
“It has also been shown that those who are on SLIT therapy may have some permanent effect after about 2 to 3 years, much like with shots, which have been seen to potentially “cure” allergies at least for a few years. There are some early studies on SLIT that looked 2 to 3 years out and it seems they too have a prolonged effect.”
Dr. Randhawa believes diagnostic advances promise to assist physicians in managing allergic disease more effectively. “Component resolved diagnostics are a new advancement in the diagnostic field of allergy,” he says. “Allergen component specific IgE allows for increased sensitivity in isolating which components of a pollen are most immunogenic, and offers a glimpse at cross-reactive sub-component classes amongst several allergen molecule classes. In particular, component resolved diagnostics are now FDA cleared for peanut allergy diagnosis.”
“The management of allergic airway disease, particularly asthma, will focus on the discrete need to test for allergic disease as part of the treatment paradigm involved in asthma,” he concludes. “As part of the NIH 2007 guidelines, this approach will only continue to be enforced.”
- Asthma and Allergy Foundation of America. http://www.aafa.org/display.cfm?id=9&sub=30
- Guidelines for the Diagnosis and Management of Asthma; National Heart Lung & Blood Institute, National Institutes of Health
- Wood RA, et al. Ann Allergy Asthma Immunol. 2007;99(1):34-41.
- Wang J, et al. J Allergy Clin Immunol. 2008;121(5):1219-1224.
- Lin S, Erekosima N, Kim J, Ramanathan M, Suarez-Cuervo C, Chelladurai Y, Ward D, Segal J. Sublingual Immunotherapy for the Treatment of Allergic Rhinoconjunctivitis and Asthma. A Systematic Review. JAMA. 2013;309(12):1278-1288.
Released on Monday, June 03, 2013