Current issues of ACP Journal Club are published in Annals of Internal Medicine


Diagnosis

Review: Skin and in vitro tests for allergic rhinitis vary widely in usefulness

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ACP J Club. 2004 Sep-Oct;141:46. doi:10.7326/ACPJC-2004-141-2-046


Clinical Impact Ratings

GIM/FP/GP: 5 stars

Allerg & Immunol: 5 stars


Source Citation

Gendo K, Larson EB. Evidence-based diagnostic strategies for evaluating suspected allergic rhinitis. Ann Intern Med. 2004;140:278-89. [PubMed ID: 14970151]


Abstract

Question

In patients presenting with nasal symptoms, how do different testing strategies compare for diagnosing allergic rhinitis?

Methods

Data sources: MEDLINE (January 1995 to March 2003), references of practice guidelines and review articles, and specialists.

Study selection and assessment: Studies that compared skin tests or in vitro tests with a gold standard. Gold standard tests involved 1 of 3 methods: clinical criteria (established by ≥ 2 clinicians correlating patients' symptoms and signs); a composite (history and examination plus ≥ 1 of skin tests, in vitro tests, and nasal provocation tests); and a nasal challenge (nasal passages are exposed to an allergen in increasing concentrations). Non-English language studies, studies on children, and studies that did not report results for patients with and without allergic rhinitis were excluded.

Outcomes: Sensitivity, specificity, and likelihood ratios.

Main results

7 studies met the selection criteria and excluded the index test from the gold standard. The most rigorous gold standard was considered to be the nasal challenge. The studies evaluated puncture and intradermal skin tests, and in vitro tests including the Phadiatop test (a second-generation in vitro test) for cat, tree, grass, mold, mite, and multiallergens. The results are in the Table.

Conclusion

Diagnostic tests for allergic rhinitis vary considerably in sensitivity and specificity according to test type and suspected allergens.

Source of funding: Not stated.

For correspondence: Dr. E.B. Larson, Group Health Cooperative, Seattle, WA, USA. E-mail larson.e@ghc.org.


Table. Diagnostic performance of tests for allergic rhinitis that do not include the index test in the gold standard*

Tests Allergen Gold standard Sensitivity Specificity +LR −LR
Puncture Cat Challenge 94% 81% 4.9 0.08
Clinical 57% 84% 3.6 0.51
Tree Challenge 97% 94% 16.2 0.03
Grass Challenge 97% 70% 3.2 0.04
Clinical 75% 89% 6.8 0.28
Mold Challenge 95% 92% 11.8 0.05
Mite Challenge 97% 76% 4.1 0.03
Intradermal Cat Challenge 60% 32% 0.9 1.24
Clinical 81% 67% 2.5 0.28
Grass Challenge 33% 68% 1.1 0.98
Clinical 79% 84% 4.9 0.25
Mold Challenge 95% 89% 8.8 0.05
In vitro Cat Composite 63% 91% 7.0 0.41
Challenge 87% 91% 9.4 0.14
Clinical 61% 82% 3.4 0.48
Tree Challenge 82% 100% 0.18
Grass Composite 80% 99% 80.0 0.20
Challenge 94% 70% 3.1 0.09
Clinical 65% 86% 4.6 0.41
Weed Composite 61% 97% 20.3 0.40
Mold Composite 56% 96% 14.0 0.46
Challenge 81% 95% 15.0 0.20
Mite Composite 19% 97% 6.3 0.84
Challenge 88% 26% 1.2 0.46
“Phadiatop”† Multiallergen Composite 96% 94% 16.0 0.04
Clinical 77% 81% 4.0 0.28

*Diagnostic terms defined in Glossary.
†Pharmacia-Upjohn, Uppsala, Sweden.


Commentary

The review by Gendo and Larson analyzes the value of allergy testing for the diagnosis and management of allergic rhinitis. The authors conclude that a therapeutic trial of allergy medication, without diagnostic testing, is indicated as a first-line intervention when a high pretest probability exists, in view of the minimal adverse effects for these medications. Diagnostic testing is of value when patients do not respond to medication, permitting specific allergens to be identified so that avoidance measures or specific immunotherapy can be started. Testing may also be valuable when a relatively low pretest probability exists and a positive result would lead to a posttest probability that is high enough to warrant a decision to treat.

There are 3 fundamental principles of managing allergic rhinitis: first, avoid allergic triggers where possible; second, use standard pharmacotherapy to manage symptoms; and third, use specific immunotherapy if the preceding measures do not provide sufficient benefit. The recent classification of allergic rhinitis (1) based on frequency (intermittent or persistent) and severity (mild, moderate, or severe) also serves as a useful guide to therapy. The conclusions of the review are most applicable to pollen-sensitive seasonal allergic rhinitis, where the clinical pattern strongly suggests high pretest probability, the duration of symptoms is limited, and allergen avoidance is difficult. However, in persistent rhinitis, identification of allergic triggers is an important initial part of management, as allergen avoidance or removal may obviate the need for medication. Otherwise, medication, with its attendant costs, may need to be maintained over the long term although it may be efficacious with a low side-effect profile. Similarly, a negative allergy test is important in this context to guide clinical decisions and prevent unnecessary allergen avoidance. Hence, the conclusions and decision-making models are relevant for certain intermittent patterns of allergic rhinitis, but less so for persistent rhinitis, particularly of a moderate-to-severe degree.

Frank Thien, MD, FRACP, FCCP
Alfred Hospital and Monash University
Melbourne, Victoria, Australia


Reference

1. Bousquet J, Van Cauwenberge P, Khaltaev N. Allergic rhinitis and its impact on asthma. J Allergy Clin Immunol. 2001;108:S147-334. [PubMed ID: 11707753]