The practice of allergology

The practice of allergy involves the diagnosis and care of patients with:

• Rhino-conjunctivitis, along with nonallergic rhinopathy

• Sinusitis, both acute and chronic, alone or complicated with nasal polyps 

• Otitis and Eustachian tube disorders 

• Asthma and all its forms including cough-variant asthma and exercise-induced asthma 

• Cough from all causes 

• Bronchitis, chronic obstructive pulmonary disease (COPD) and emphysema 

• Hypersensitivity pneumonitis 

• Alveolitis 

• Atopic dermatitis/eczema 

• Contact dermatitis 

• Urticaria and angioedema 

• Drug allergy 

• Food allergy 

• Latex allergy 

• Insect allergy and stinging-insect hypersensitivity 

• Gastrointestinal reactions resulting from allergy, including eosinophilic esophagitis and gastroenteritis 

• Anaphylactic shock

• Immunodeficencies, both congenital and acquired 

• Occupational allergic diseases 

• Identifying and managing risk factors for progression of allergic diseases — the «allergic march» 

• Other specific organ reactions resulting from allergy

• Conditions that may mimic or overlap with allergic disease 

• An expert knowledge of the epidemiology and genetics of allergic diseases Immunodeficencies and autoimmune diseases, with special knowledge of regional and local allergens

As part of the practice of allergy, the allergist should be capable of ordering and interpreting allergy-and immunology-related laboratory tests:

• Evaluating total IgE and allergen specific IgE measurements

• Carrying out appropriate provocation testing for allergic and immunologic disease 

• Providing analysis and advice regarding local environmental/airborne allergens and irritants, as well as the analysis and advice regarding ingested allergens/ irritants

• Conducting and/or evaluating tests of pulmonary function and tests of inflammatory markers

• Conducting and/or evaluating tests of nasal function; this may include examination of nose and throat via fiberoptic rhinoscopy and nasal endoscopy 

• Specific allergen and venom immunotherapy 

• Providing pharmacotherapy of allergic disorders and related diseases including aero-allergens, drugs, venoms, occupational allergens, and food allergens 

Because of the highly specialized training, the allergist can advise both patients and other members of the medical community on:

 The role of effector cells involved in allergic disease (stem cells, • lymphocytes, mast cells, basophils, eosinophils, neutrophils, • monocytes, macrophages, dendritic cells) 

• The molecules involved in the immunological response (both innate and acquired) including chemical mediators; immunoglobulins; antibodies; complement; cytokines;interleukins; chemokines and their receptors; human leukocyte antigen/major histocompatibility complex (HLA/MHC) antigens • The main hypersensitivity reactions 

• Cell-to-cell interactions 

• The scientific in vitro laboratory diagnostic tests for allergy and 

• their selection and interpretation, including allergenspecific in vitro assays; enzyme-linked immunosorbent assays (ELISAs); Western blotting; tests for inflammatory markers, protein and cellular antigen stimulation tests; histamine release assays

The allergist is especially competent in performing/interpreting the following: 

• Allergic history and physical examination 

• Skin testing 

• Where necessary, investigating alternative diagnoses 

• Environmental modification strategies to reduce allergen exposure 

• Specific immunotherapy (allergen vaccines; both oral and injective)

• Immunomodulatory therapy 

• Drug desensitization 

• Evaluation and treatment of allergic and immunologic competence 

• Management and treatment of anaphylactic shock 

• Education for patients, caregivers and primary care physicians 

An overview of allergens

An allergen is any antigenic substance that can mediate an immediate hypersensitivity reaction with an associated clinical reaction in an individual. Common allergens include pollens, fungal spores, house-dust mites, and animal epithelial materials but can also include drugs, biological products, and insect venoms. Most allergens are proteins or glycoproteins that range in molecular weight from 5000 to 100,000 Da, although polysaccharides and low molecular weight substances also may be allergenic.1 Little is known, but much research is dedicated to determining the distinguishing facts that make an antigen capable of inducing IgE production (an allergen) in contrast to antigens that induce other immunologic responses (IgG and IgA). Factors that have already been shown to increase immunogenicity of an antigen include molecular size, solubility, stability, conformational fold, and duration of exposure

Allergens enter the body via inhalation, ingestion, or may be injected. Genetic predisposition and environmental factors determine if an individual will be sensitized to an allergen, and then subsequent allergen exposure of sufficient concentration triggers a physiological response by interacting with specific IgE bound to mast cells and basophils. The ensuing inflammatory cascade elicits a variety of signs and symptoms in the allergic spectrum. The allergic response is dependent on the route of exposure. If exposure is to an inhaled aeroallergen, the allergic response will be a respiratory reaction in nature. Ingested or injected exposure gives rise to gastrointestinal, cutaneous, or systemic reactions. 

An allergen is recognized by the International Union of Immunologic Societies as a protein that has allergenicity in at least five individuals.2 Individual allergens are further divided into major and minor allergens when it comes from the same source, e.g., giant ragweed pollen or cat dander. Major allergens result in an IgE response in 50% of allergic individuals allergic to the specific source, whereas minor allergens cause an allergic response in
50%. Although “minor” is in the name, they still cause a significant allergic response in an individual. 

Nomenclature for allergen proteins has been established by the International Union of Immunologic Societies. The standard nomenclature uses the first three letters of the genus, followed by the first letter of the species, and then an Arabic numeral; they are not italicized. 

POLLENS

For pollen to be clinically significant as an aeroallergen, it must be buoyant, present in significant numbers, and be allergenic. Most pollens that cause clinical disease are 20 – 60
m in diameter.2 This small size allows exposure through wind carriage and contact with the respiratory mucosa and conjunctiva. Particles
7
m tend to deposit in the airways, and those
3
m may enter the distal airways. Pollen immunogenicity, plant abundance, proximity to living environments, and regional geography determine specific pollens that are responsible for local allergic sensitization.2 

Grass pollen is the most common cause of allergic rhinitis and asthma worldwide because of the wide distribution of wind-pollinating grasses. Most are 20 –25
m in diameter and, therefore, tend to cause symptoms of rhinitis rather than asthma. Most grasses belong to the same family (Poaceae) and have significant cross-reactivity, with the exceptions of Bermuda and Bahia grass, which are subtropical grasses. Ryegrass (major allergen Lol p 1) and Timothy grass (major allergen Phl p1) are among the most important allergenic grasses. Grass pollen is typically released in the afternoon, and in the Midwest, is prevalent in the months of May through July. Many southern areas, such as Florida and southern California, have grass seasons lasting as long as 10 –11 months. 

Ragweed pollen is the most important cause of allergic rhinitis and pollen asthma in North America. Ambrosia artemisiifolia (short ragweed; major allergen Amb a 1) and Ambrosia trifida (giant ragweed; Amb t 5) are the most important ragweed pollen allergens. Pollen grains are 16 –20
m in diameter and are notorious for triggering allergic symptoms in the central and eastern United States; Ontario, Canada; and increasing locations in Europe.5,6 Weed pollen release depends on seasonal daylight variation and is released typically in the morning during the autumn season in the United States. A single ragweed plant may expel 1 million pollen grains in a single day. It possesses the ability to travel hundreds of miles from its source. In the Chicago area, ragweed pollen is prevalent from August 15 to October 1.

Medical Decision-Making

Medical decision-making coding includes the number of diagnoses and treatment options, the amount of data and the complexity of data and risk.

Diagnosis and treatment options: 

• New problem – a problem new to the physician 

• Established problem, stable – a known diagnosis that is stable 

• Established problem, worsening – a known diagnosis that is worse 

• Established problem, improved – a known diagnosis that has improved 

• Work-up planned – a new complaint for which additional work-up is planned 

• No work-up planned – new complaint(s) for which no additional work-up is planned

Coding for the amount and complexity of data component is composed of the following information, which is obtained, ordered or reviewed during the encounter:

• Review/order lab tests 

• Review/order routine x-rays 

• Review/order test from medicine section 

• Discuss test results with performing physician 

• Decide to obtain old records and documents 

• Document direct visualization and independent interpretation

The risk component is composed of the present problem, diagnostic procedure or management option. The risk is determined by the component of the highest level to determine the overall risk for the patient.

Presenting problems are described as: 

• Minimal – one self-limited or minor problem 

• Low – two or more self-limited or minor problems, one stable chronic illness or one acute uncomplicated illness/injury 

• Moderate – one or more chronic illness with mild exacerbation, two or more stable chronic illnesses, undiagnosed new problem with uncertain prognosis, acute illness with systemic symptoms or acute complicated injury 

• High – chronic illness with severe exacerbation or acute or chronic illness/injury that may pose a threat to life or bodily function

The component for diagnostic procedures ordered is described as: 

• Minimal – lab tests requiring venipuncture, x-rays, ultrasound 

• Low – superficial needle biopsies, skin biopsies, PFTs

• Moderate – diagnostic endoscopy, deep needle or incisional biopsy 

• High – diagnostic endoscopy with risk factors

Management options are described as:

 • Minimal – rest, gargles, elastic/superficial dressings

 • Low – over-the-counter drugs, saline washes, minor surgery, physical therapy

 • Moderate – minor surgery with risk, elective major surgery, prescription drug management

 • High – elective major surgery with risk, emergency major surgery, decision not to resuscitate or de-escalate care because of poor prognosis, drug therapy requiring intensive monitoring for toxicity, high morbidity and mortality without treatment

The level of medical decision-making depends on the number of diagnoses, the amount and complexity of the data and the risk. The appropriate level is determined by choosing the level where the middle component rests, or where two out of three of the components meet. For example, a new patient presents with asthma and allergic rhinitis. The patient is allergy tested, has a PFT and is placed on a prescription medication. The appropriate level of medical decision-making would be moderate for this patient. If a comprehensive history and a comprehensive exam were also performed and documented, the physician would code for a 99204 level of service.