Delivered by Ingenta to: University of Iowa IP: 79.110.18.178 On: Tue, 07 Jun 2016 04:38:34 Copyright (c) Oceanside Publications, Inc. All rights reserved. For permission to copy go to https://www.oceansidepubl.com/permission.htm Determination of Cut-Off Positivity Values in Nasal Challenge Testing of Patients with Allergic Rhinitis Gian Galeazzo Riario-Sforza, M.D.,* Cristoforo Incorvaia, M.D.,# Roberto Bellotto, M.D.,§ Rossana Salimbeni, M.D.,* Mario Fumagalli, M.D.* ABSTRACT Nasal challenge testing with allergen extracts is currently used to diagnose nasal allergy and, to a greater extent, in studies of pathophysiology of allergic rhinitis. The resulting nasal obstruc- tion, measured as nasal airway resistance (NAR), is determined by rhinomanometry (RMM). The aim of this study was to define a cut-off NAR value for a positive response in a nasal allergen challenge test. Forty-two grass-allergic adult patients and 40 nonallergic adults were challenged out of the grass pollen season under standard conditions with timothy grass extract administered intranasally in doses increasing from 10 to 1500 1U/mL. 1nspira- tory NAR was determined by computerized anterior active RMM. The cut-off value for a positive test was determined from receiver operating characteristic curves plotted from these data with the LABROC1 computer program. In addition, the subjects' nasal cycle was recorded during the four hours preceding the allergen challenge. The patients' mean NAR value at baseline (0.33 Palce! sec) and when challenged with normal saline solution did not differ from those of the control subjects. The patients, but not the control subjects, experienced typical nasal allergic symptoms when challenged with the grass extract. The control subjects had no symptoms and their NAR did not change significantly when they were challenged with the same extract. All 42 allergic patients had measurable increases in NAR at the 800 IU/mL allergen dose; i9/42 patients had complete obstruction (i.e., NAR unmeasurable) From the *Allergy Unit, Division of Internal Medicine-Buzzi Hospital, Milan, #Department of internal Medicine, Infectious Diseases and Immunopathology-University of Milan, Milan, and §ENT Division, Buzzi Hospital, Milan, Italy Address correspondence and reprint requests to Gian Galeazzo Ria rio-Sforza, M.D., Allergy Unit, Istituti Clinici di Perfeziona- mento, Ospedale cro., Via Bignami i, 20126 Milan, Italy Allergy and Asthma Proc. when challenged with the 1500 IU/mL dose. The maximum diag- nostic value (= sensitivity + specificity at the discriminator po- sition on the receiver operating characteristic curves) was i.96 with the 800 IU/mL dose. At that dose, the NAR cut-off value was 0.91 Pain/sec, which was 2.7 times greater than their mean value at baseline. NAR varied less than i-fold between the maximum and minimum points of the normal nasal cycle in both groups of subjects. An increase of NAR of nearly threefold during nasal allergen challenge compared to the baseline value determined by computerized anterior active RMM discriminates best patients with allergic rhinitisfromnonallergic adults. (Allergy and Asthma Proc 20:109-114, 1999) INTRODUCTION N asalchallenge testing with allergen extracts is currently used in diagnosing nasal allergy and, to a greater extent, in studies of the pathophysiology of allergic rhini- tis. l A positive response to the challenge depends on the elicitation of typical allergic symptoms, including sneezing, rhinorrea, and obstruction of the nasal airway.2 Although the number of sneezes can easily be counted, and the quantity of nasal secretions is easily measured, the degree of obstruction, measured as nasal airway resistance (NAR), has to be determined by a more sophisticated method, namely, rhinomanometry (RMM).3 There are several RMM techniques, the type now used most frequently being anterior active RMM. The equipment consists of a short length of tubing that is sealed in the nostril, paying attention not to deform it. This tubing is connected to a pneumotachygraph, which, in tum, is linked via an analog-digital converter to a PC/AT 486 computer. The computer calculates NAR from the flow-pressure data recorded by the pneumotachygraph. This noninvasive test is reported to be reliable and easy to perform,3 though the 109