Intravenous olfactory test latency correlates with improvement in post-infectious olfactory dysfunction.

Horikiri, Kyohei; Kikuta, Shu; Kanaya, Kaori; Shimizu, Yuya; Nishijima, Hironobu; Yamasoba, Tatsuya; Kondo, Kenji

CONCLUSION This cohort study showed that onset latency in the intravenous olfactory test (IVO) may help predict when olfaction in patients with post-infectious olfactory dysfunction (PIOD) improves. OBJECTIVES To identify factors that predict the olfactory improvement period in patients with PIOD. METHODOLOGY/PRINCIPAL All consecutive patients presenting with PIOD in 1994-2014 who were followed up for 2 years were identified retrospectively. The ability of demographic/clinical factors (age, sex, body mass index, presence/absence of allergic rhinitis, treatment/non-treatment with herbal medicines, patient dependence on herbal medicine treatment, presence/absence of diabetes mellitus, and smoking status) and olfactory test factors (response/no response and onset latency and duration in the IVO test, and detection and recognition scores on the T&T olfactory test) to predict the olfactory improvement period (defined respectively as the time from PIOD onset or olfactory testing to the first self-report of olfaction improvement) was analyzed by univariate and multivariate regression. RESULTS Of the 187 PIOD patients, the prognostic ability of demographic/clinical factors was analyzed in 65. None predicted the olfactory improvement period. Of the 65 patients, 20 did not respond in the IVO test. In the remaining 45 patients, onset latency (but not the other olfactory test factors) was a significant prognosticator of olfactory improvement period (R2=0.24, p = 0.003).