Efficacy of a Screening Radioallergosorbent Test

Abstract

\s=b\ Controversy over the routine use of the radioallergosorbent test (RAST) for initial inhalant allergy diagnosis largely concerns expense to the patient. Presented is a method for utilizing the RAST, with all its inherent advantages, at a competitive cost to both negatively and postively responding patients. The initial use of a "screening" RAST that utilizes approximately one third the number of tests in the usual full RAST battery is recommended. When all responses on the screening RAST battery are negative, further RAST testing proves generally unnecessary. For positive responders, the screening RAST often eliminates the need of additional pollen and/or mold allergen testing, a further cost-containment feature. The presented study illustrates the efficacy of this technique. A background section is provided to familiarize the reader with the common modalities available for testing and treating IgE-mediated inhalant allergies. (Arch Otolaryngol 1982;108:781-786) The radioallergosorbent test (RAST) provides an alternative to skin testing for the diagnosis of IgE-mediated inhalant allergy. The practicality of the RAST is controversial among allergists.1"' Since the cou¬ pling of the Fadal/Nalebuff6 (F/N) Modified RAST's higher sensitivity with the Phadebas Conventional RAST's6 inherent specificity, the prin¬ cipal debate appears to focus on cost to the patient. The RAST critics believe that the initial patient cost as opposed to that of skin testing is unacceptable. Proponents of the RAST counter that elimination of skin-test faults1015 allows superior accuracy, convenience, safety, and efficacy of treatment, with a resulting overall cost-effectiveness.Validity in both opinions appears to exist. The overall cost appears gener¬ ally less for the RAST positive responder, despite a higher initial test expense. The modality of therapy obviates unnecessary treatment of patients with false-positive skin responses, and allows a more potent and safe starting dose for immuno¬ therapy. Overall cost-efficiency re¬ sults.679 The skin-testing techniques are more cost-effective when only negative test responses occur. Initial use of a "screening" RAST that utilizes approximately one third of the allergens in the usual full RAST battery appears to negate this con¬ flict. The suggested screen has proved over 99% efficient and sensitive against the occurrence of a definite RAST positive response (F/N class 2 or greater) on full battery testing. The efficiency is 96% and the sensitivity is over 94% when equivocal positive RAST scores (F/N class 1) are in¬ cluded. The financial savings to the patient with only negative responses merit the few days of delay required for indicated additional tests on patients showing a positive screen. Utilization of other screening features also may provide cost-containment benefits for the positive-responding patients by disallowing the need for further pollen and/or mold allergen testing. BACKGROUND

The screening RAST: Is it a valid concept?

“…The most obvious means to reduce the cost of RAST testing is by limiting the number of antigens screened. This study confirmed King's 1 findings of the efficacy of a screening RAST. Although the 6‐antigen screen in this study provided 91% sensitivity and 93% efficiency, the 9‐antigen midiscreen essentially offered the same sensitivity and efficiency (nearly 100%) of the expanded 13‐antigen screen.…”

Skin Testing for Inhalant Allergy 2003: Current Strategies

“…Screening panels can be as narrow as 6 to 8 antigens. 17 Panels with 12 to 14 antigens, however, have been shows to have better sensitivity in the detection of inhalant allergy, and their use is consistent with the 2003 AAOA recommendations. 18,19 Several principles are essential in the use of screening methods for inhalant allergy.…”

Comparison of mRAST and CAP with Skin end Point Titration for Altemaria Tenuis and Dermatophagoides Pteronyssinus

“…To improve reliability and usefulness, there have been many modifications in testing, but the basic principles of allergosorbent testing remain the same. Despite the drawbacks of in vitro testing, it is ideally suited to be used as a screening tool for allergies 3,4 . In vitro screening can predict 90% to 95% of allergic patients.…”