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Wise et al.

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tests, in vitro measurement of sIgE) are inconclusive. The NPT is designed for AR, while conjunctival provocation test (CPT) may be used in patients with rhinoconjunctivitis or AR alone. 1069,1070 Nasal challenge.: The aim of nasal challenge is to reproduce the response of the upper airway upon nasal exposure to allergens. 1071,1072 However, currently the only technique fulfilling this aim is the EEC (as described in the previous section), while the allergen amounts administered during an NPT usually exceed natural exposure levels, sometimes to a large extent. The allergen for NPT can be administered by various devices, including syringes, nose droppers, micropipettes, nasal sprays, or impregnated disks, none of them being free from limitations or pitfalls. 1071 The result of a NPT can be assessed by several measures, including symptom scores (especially the TNSS), rhinomanometry, acoustic rhinometry, optical rhinometry, peak nasal inspiratory flow, inflammatory markers in nasal lavage fluid, and nasal NO concentration. 1072 Contraindications to NPT are acute bacterial or viral rhinosinusitis, exacerbation of AR, history of anaphylaxis to allergens, severe general diseases, and pregnancy. 1073 Recent studies evaluating the sensitivity and specificity of the different techniques using specific allergens are available (Table VIII.H.2). It is apparent from the contrasting findings that a standardized technique for NPT is not yet available. In fact, in the coming years, the use of NPT in the diagnosis of AR is likely to decrease, due to the diagnostic ability of emerging tools such as CRD 1074 and the BAT, 1075 which are able to identify the causative allergen in patients with dubious results from initial analysis. Despite its limitations, a pivotal role for NPT is currently acknowledged in diagnosis of occupational rhinitis and LAR. According to the position paper of the EAACI, occupational rhinitis “can only be established by objective demonstration of the causal relationship between rhinitis and the work environment through NPT with the suspected agent(s) in the laboratory, which is considered the gold standard for diagnosis.” 84 The best time to perform a NPT is in the morning to limit the effects of common daily-life stimuli. Baseline evaluation of symptoms and nasal function should be done after adaptation to room temperature. A control test must be performed to ensure that the nasal response is specific to the tested agent. 1076 A positive control test suggests rhinitis induced by irritants or nonspecific hyperresponsiveness. In regard to LAR, the absence of sIgE in serum and in the skin requires that IgE are found locally or that they are revealed by a positive NPT. 1077 Despite the introduction of techniques to detect IgE in the nose in the 1970s, 1078 the ability to measure locally-present IgE in the clinic setting is not currently available. This makes NPT of critical importance, though contrasting observations have been reported. NPT with mites, pollens and Alternaria was positive in 100% of 22 adults with previously diagnosed LAR, 1079 but in a case controlled, prospective study on 28 children with a diagnosis of NAR, tested with mites and grass pollen, NPT was positive in only 25% of subjects. 293 Conjunctival challenge.: While several different techniques exist for NPT, CPT is generally performed by instilling 20 to 30 μ L of an allergen solution into the inferior external quadrant of the ocular conjunctiva, using diluent in the contralateral eye as a control. 1069 Also, the

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Int Forum Allergy Rhinol . Author manuscript; available in PMC 2020 June 10.