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Tuesday, March 10, 2009

Post #15 An Allergy Update

If you (or your loved one) suffer from allergies and you want some good evidence-based facts - keep reading. This particular blog entry is a bit tedious as I have tried to include a complete amount of information on allergies (their causes, the tests to diagnose, and treatment).

The article (published in August of 2008) posted below is essentially a doctor's CliffsNotes on allergies. It is a practice guideline reviewing a vast amount of articles and research on allergies; the actual article is 84 pages long with a bibliography of 998 articles. The task force has made the article user friendly by summarizing the essential 109 points that the group wanted to highlight.

You ask, "How essential can a list of 109 items be?"

Excellent question.

I have further pared down the article from 109 points to the 40 most essential "essential points" that the lay person would be interested in.

Each recommendation is listed with a letter demarcating the strength of evidence supporting the "essential point's" statement. For example an "A" indicates relatively strong evidence, with each lower letter grade representing lesser strength.

However, take careful notice that a weaker letter does not mean the statement is any less true; it simply denotes that currently, the body of evidence supporting the statement has not been fully flushed out in strong clinical studies (which may or may not happen in the future).

The take home points (with a sprinkling of my spin on things) are these:

1. Allergies are complex and can be confused with COLDS as they present very similarly. Treatment however is different. Colds cannot be treated (for the most part), allergies can be treated (more on this below).

2. Testing for allergies can be done by skin tests or blood tests. Generally, the skin tests are more sensitive and preferred.

3. Common sense: Avoid the things that make you allergic. A few allergen specific recommendations are listed below. For example, if you have a pollen allergy, track pollen counts and avoid the outdoors accordingly.

4. Intranasal corticosteroids (Flonase, Rhinocort, Nasonex) are the most effective medication class for controlling symptoms of allergic rhinitis.

5. Antihistamines (intranasal and oral) are also good to control symptoms. For the most part, second generation oral antihistamines (Claritin, Zyrtec, Allegra) are preferred over the first generation oral antihistamines (Benadryl) because they are less sedating.

6. Most allergy medication brands are interchangeable in terms of effectiveness, i.e. Claritin, Zyrtec, and Allegra are all equally effective.

7. In general, regardless of the cause of the allergy (whether it be pollen, dust mites, pets, etc.), the battery of medications used will be the same. Therapy only deviates when allergen immunotherapy (weekly allergy shots) are necessary. Thus, it is probably only necessary to visit the allergy specialist when medication therapy has been exhausted and the patient potentially requires either exact identification of the offending allergen (in order to better avoid the cause) and/or desires to initiate allergen immunotherapy.

8. For cases, uncontrolled by above said medications, it is probably time to see the allergist.

9. The key is to expect reasonable control of symptoms and not a cure and gear therapy towards achieving that goal.

The article's key points posted below. . .

The diagnosis and management of rhinitis: An updated practice parameter
Wallace DV, Dykewicz MS, Bernstein DI, Blessing-Moore J, Cox L, Khan DA, et al. J Allergy Clin Immunol. 2008 Aug:122(2).

These parameters were developed by the Joint Task Force on Practice Parameters, representing the American Academy of Allergy, Asthma & Immunology; the American College of Allergy, Asthma and Immunology; and the Joint Council of Allergy, Asthma and Immunology.

Classification of recommendations and evidence

Category of evidence

Ia. Evidence from meta-analysis of randomized controlled trials
Ib. Evidence from at least 1 randomized controlled trial
IIa. Evidence from at least 1 controlled study without randomization
IIb. Evidence from at least 1 other type of quasi-experimental study
III. Evidence from nonexperimental descriptive studies, such as comparative studies
IV. Evidence from expert committee reports or opinions or clinical experience of respected authorities, or both
LB Evidence from laboratory-based studies.
NR Not rated.

Strength of Recommendation

A Directly based on category I evidence
B Directly based on category II evidence or extrapolated recommendation from category I evidence
C Directly based on category III evidence or extrapolated recommendation from category I or II evidence
D Directly based on category IV evidence or extrapolated recommendation from category I, II, or III evidence


Burden and epidemiology of rhinitis
10. The influence of early childhood exposure to infections, animals, and secondary tobacco smoke on the development of atopy and allergic rhinitis is still unknown. C


13. The symptoms of allergic rhinitis result from a complex allergen-driven mucosal inflammation caused by interplay between resident and infiltrating inflammatory cells and a number of vasoactive and proinflammatory mediators, including cytokines. Sensory nerve activation, plasma leakage, and congestion of venous sinusoids also contribute. C

Associated allergic conjunctivitis
19. Intranasal corticosteroids, oral antihistamines, and intranasal antihistamines have similar effectiveness in relieving ocular eye symptoms associated with rhinitis. A

Infectious rhinitis
24. Viral infections account for as many as 98% of acute infectious rhinitis and the majority of rhinitis symptoms in the young child. Routine nasopharyngeal cultures when bacterial infections are suspected do not add diagnostic value. C


Skin Testing
39. Skin tests are the preferred tests for the diagnosis of IgE-mediated sensitivity. The number of skin tests and the allergens selected for skin testing should be determined on the basis of the patient’s age, history, environment, and living situation, such as area of the country, occupation and activities. D

In vitro asaays for specific IgE
40. The precise sensitivity of specific IgE immunoassays compared with skin prick/puncture tests is approximately 70% to 75%. Immunoassays have similar sensitivity to skin tests in identifying those patients with nasal symptoms elicited after natural or controlled allergen challenge tests. C

41. Interpretation of specific IgE immunoassays may be confounded by variables such as potency of allergens bound to solid support systems, cross-reactive proteins and glycoepitopes, specific IgG antibodies in the test serum, and high total IgE. D

43. Nasal smears for eosinophils are not necessary for routine use in diagnosing allergic rhinitis when the diagnosis is clearly supported by the history, physical examination and specific IgE diagnostic studies but may be a useful adjunct when the diagnosis of allergic rhinitis is in question. C

46. The measurement of total IgE and IgG subclasses for the diagnosis of allergic rhinitis has limited value and should not be routinely performed. C


Environmental control measures
52. The most common allergic triggers for rhinitis include pollens, fungi, dust mites, furry animals and insect emanations. B

53. The types of pollen responsible for rhinitis symptoms vary widely with locale, climate, and introduced plantings. B

54. Highly pollen-allergic individuals should limit exposure to the outdoors when high pollen counts are present. B

57. Clinically effective dust mite avoidance requires a combination of humidity control, dust mite covers for bedding, high efficiency particulate air (HEPA) vacuuming of carpeting and the use of acaricides. B

58. Avoidance is the most effective way to manage animal sensitivity. D

59. Cockroaches are significant cause of nasal allergy, particularly in inner-city populations. C


Oral antihistamines
63. There are important differences among the second-generation antihistamines in regard to their sedative properties: fexofenadine, loratadine, and desloratadine do not cause sedation at recommended doses; loratadine and desloratadine may cause sedation at doses exceeding the recommended dose; cetirizine and intranasal azelastine may cause sedation at recommended doses. A

64. Among the newer, nonsedating antihistamines, no single agent has been conclusively found to achieve superior overall response rates. C

Intranasal antihistamines
66. Intranasal antihistamines are efficacious and equal to or superior to oral second-generation antihistamines for treatment of seasonal allergic rhinitis. A

69. Intranasal antihistamines are generally less effective than intranasal corticosteroids for treatment of allergic rhinitis. A

Oral and topical decongestants
70. Oral decongestants, such as pseudoephedrine and phenylephrine, are α-adrenergic agonists that can reduce nasal congestion but can result in side effects such as insomnia, irritability and palpations. A

71. Oral and topical decongestants agents should be used with caution in older adults and young children, and in patients of any age who have history of cardiac arrhythmia, angina pectoris, cerebrovascular disease, hypertension, bladder neck obstruction, glaucoma, or hyperthyroidism. C

72. Topical decongestants can be considered for short-term and possibly for intermittent or episodic therapy of nasal congestion, but are inappropriate for regular daily use because of the risk for the development of rhinitis medicamentosa. C

Over-the-counter cough and cold medications for young children
73. The efficacy of cold and cough medications for symptomatic treatment of upper respiratory tract infections has not been established for children younger than 6 years. Because of the potential toxicity of these medications, the use of these over-the-counter (OTC) drugs generally should be avoided in all children below 6 years of age. A

Intranasal corticosteroids
74. Intranasal corticosteroids are the most effective medication class for controlling symptoms of allergic rhinitis. A

75. In most studies, intranasal corticosteroids have been shown to be more effective than the combined use of an antihistamine and leukotriene (LT) antagonist in the treatment of seasonal allergic rhinitis. A

76. Intranasal corticosteroids may provide significant relief of symptoms of seasonal allergic rhinitis when used not only on a regular basis but also on an as-needed basis. B

However, as-needed use may not be as effective as continuous use of intranasal corticosteroids. D

77. When comparing the available intranasal coriticosteroids, the overall clinical response does not appear to vary significantly between products irrespective of the differences in topical potency, lipid solubility and binding affinity. C

78. Intranasal corticosteroids may be useful in the treatment of some forms of nonallergic rhinitis. A

79. Intranasal corticosteroids when given in recommended doses are not generally associated with clinically significant systemic side effects. A

80. Although local side effects are typically minimal with the use of intranasal corticosteroids, nasal irritation and bleeding may occur. Nasal septal perforation is rarely reported. B

Oral corticosteroids
81. A short course (5-7 days) of oral corticosteroids may be appropriate for the treatment of very severe or intractable nasal symptoms or to treat significant nasal polyposis. However, single administration of parenteral coritcosteroids is discouraged and recurrent administration of parenteral coritcosteroids in contraindicated because of greater potential for long-term corticosteroid side effects. D

Oral anti-leukotriene agents
85. Oral anti-LT agents alone, or in combination with antihistamines, have proven to be useful in the treatment of allergic rhinitis. A

87. There is evidence that topical saline is beneficial in the treatment of the symptoms of chronic rhinorrhea and rhinosinusitis when used as a sole modality or for adjunctive treatment. A

Allergen immunotherapy
88. Allergen immunotherapy is effective for the treatment of allergic rhinitis. A

89. Allergen immunotherapy should be considered for patients with allergic rhinitis who have demonstrable evidence of specific IgE antibodies to clinically relevant allergens, and its use depends on the degree to which symptoms can be reduced by avoidance and medication, the amount and type of medication required to control symptoms, and the adverse effects of medications. A

90. Allergen immunotherapy may prevent the development of new allergen sensitizations and reduce the risk for the future development of asthma in patients with allergic rhinitis. B


100. A sufficient amount of human observational data has now been accumulated to demonstrate safety for second-generation as well as first-generation antihistamines. C

104. Intranasal corticosteroids may be used in the treatment of nasal symptoms during pregnancy because of their safety and efficacy profile. C

105. Immunotherapy for allergic rhinitis may be continued during pregnancy but without dose escalation. C

Consultation with an allergists/immunologist
109. Consultation with an allergist/immunologist should be considered for patients with rhinitis who have inadequately controlled symptoms, a reduced quality of life and/or ability to function, adverse reactions to medications, a desire to identify the allergens to which they are sensitized and to receive advice on environmental control, or comorbid conditions such as asthma and recurrent sinusitis, or when allergen immunotherapy is a consideration. C


Pharm Aid said...

Just curious, what is your evidence for Point #2 above? Skin tests are preferred by the physician community because of the high reimbursement and repetitive visits. Blood tests are preferred by patients (if they are ever presented the option of a blood test; most allergy docs usually neglect even telling the patient about it).

The only two major studies I've seen (Schmidt and Hoshimoto). In Schmidt, there was slight (although not statistically signficant) benefit of skin tests. But in Hoshimoto, there was very slight and statistically significant benefit to blood tests.

Efficacy when viewed through the lens of the physician's pocketbook can be a troubling thing.

Anonymous said...

your writing is really great..keep it up!