Intranasal Schirmer test: A useful diagnostic tool in nasal allergen provocation testing.

Background: The intranasal Schirmer test (INSCH) is a quick method to objectify nasal secretion.

Objective: To use the INSCH to assess nasal secretion change through direct nasal allergen provocation test (NPT).

Methods: This prospective single-center study included patients who received allergy diagnostics using NPT and anterior rhinomanometry. The Schirmer filter paper was attached to the nasal septum bilaterally pre- and post-allergen provocation. In addition, all participants completed the sinonasal outcome test 22. The difference in wetting length before and after allergen provocation was investigated. Moreover, a cutoff value for allergic rhinitis was calculated.

Results: A total of 25 patients and 25 individuals in the control group were included. Patients with a positive result in NPT demonstrated a significantly higher secretion in the provoked nasal cavity (mean difference = 13.95 mm; P = .01). The increased moisture level through provocation resulted in an area under the curve of 0.814. A cutoff value of 2.75 mm wetting length increase (Youden index = 0.532) was calculated (sensitivity = 81.8%; specificity = 71.4%). Allergy diagnostic patients scored significantly higher in the sinonasal outcome test 22 than the control group (25.04 score difference; P < .001).

Conclusion: The INSCH represents a straightforward and cost-effective test to assess intranasal secretion changes in allergy diagnostics. The incorporation of the INSCH 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 such as anterior rhinomanometry or acoustic rhinometry.