Reliability, validity, and sex differences in a quantitative gag reflex measurement method

A reliable assessment method is required to manage the gag reflex. We tested the inter- and intra-examiner reliability and validity of a quantitative measurement method and evaluated the differences between sexes. This study included 21 healthy adults (10 women, 11 men; mean age, 27.1 ± 9.9 years). An examiner inserted a standard saliva ejector slowly down the participant's throat to determine the maximum tolerance of the gag reflex; the insertion depth was used as an index of gag reflex. The reflex was measured by one examiner during two sessions (S1 and S3) and by a second examiner during one session (S2) under the same conditions. The galvanic skin response (GSR) and heart rate (HR) were recorded during each session to test the method validity. Data were analysed using the intraclass correlation coefficient (ICC), paired t test, and two-way repeated-measures analysis of variance. The ICC of the gag reflex measurements was 0.91 between S1 and S2, and 0.93 between S1 and S3. The GSR and HR increased significantly after the maximum tolerance of the reflex in S1, S2, and S3 (GSR: P < 0.001, P = 0.004, P = 0.001, respectively; HR: all, P < 0.001). Differences in the measurements according to sex and session were not significant. Our method exhibited excellent inter- and intra-examiner reliability and was unaffected by the participants' sex. Measurement revealed significant autonomic reactivity, which is common for this reflex. Consequently, this method may be used in clinical and laboratory-based applications.