Intranasal Schirmer Test: A Useful Diagnostic Tool in Nasal Allergen
Provocation Testing
Abstract
Goals: The intranasal Schirmer test (INS) is a quick method to
objectify nasal secretion. This study aims to use the INS to assess
nasal secretion change through direct nasal allergen provocation (NPT).
Material and Methods: This prospective single-center study
included patients who received allergy diagnostics using NPT and
anterior rhinomanometry (aRMM). The Schirmer filter paper was attached
to the nasal septum bilaterally pre- and post-allergen provocation.
Additionally, all participants completed the sinonasal outcome test 22
(SNOT-22). The difference in wetting length before and after allergen
provocation was investigated. Moreover, a cut-off value for allergic
rhinitis were calculated. Results: A total of n = 25 patients
and n = 25 in the control group were included. Patients with a positive
result in NPT showed a significantly higher secretion in the provoked
nasal cavity (mean difference = 13.95 mm; p = 0.01). The increased
moisture level through provocation resulted in an area under the curve
(AUC) of 0.814. A cut-off value of 2.75 mm wetting length increase
(Youden index = 0.532) was calculated (sensitivity = 81.8% and
specificity = 71.4%). Allergy diagnostic patients scored significantly
higher in the SNOT-22 than the control group (25.04 score difference; p
< 0.001). Conclusion: The INS represents a
straightforward and cost-effective test to assess intranasal secretion
changes in allergy diagnostics. The incorporation of the INS in the NPT
protocol could particularly enhance treatment efficacy for patients with
inconclusive NPT results or it could serve as a substitute for other
objective measurements like aRMM or acoustic rhinometry.