Clinical effects of two combinations of olfactory agents on olfactory dysfunction after upper respiratory tract infection during olfactory training

Abstract

SUMMARY OBJECTIVE To compare two combinations of olfactory agents for olfactory training therapy of olfactory dysfunction after upper respiratory tract infection (URTI) and investigate the influencing factors on clinical effects. METHODS 125 patients with olfactory dysfunction were randomly divided into two groups: test and control. During the olfactory training, four odors were used in both groups. The olfactory training lasted for 24 weeks. Then, participants were tested using Sniffin’ Sticks and threshold-discrimination-identification (TDI) composite scoring before treatment and at 1, 3, and 6 months after treatment. The TDI scores were compared at different time points between the groups and within them, and influence factors were analyzed. RESULTS There was no significant difference in TDI scores between both groups. Furthermore, TDI scores did not significantly change after one month of treatment in either of the groups. After 3 and 6 months of treatment, TDI scores both significantly increased, and the odor discrimination and identification abilities significantly strengthened in both groups; however, the odor thresholds did not improve. The course of the disease was a significant influencing factor on the therapeutic effect of olfactory training for both groups. CONCLUSION The combination of essential balm, vinegar, alcohol, and rose perfume for olfactory training, which are scents commonly found in daily life, can effectively cure URTI-induced olfactory dysfunction, and significantly improve the odor discrimination and identification abilities. Furthermore, prolonging the treatment time can help with the recovery of olfactory functions, and earlier olfactory training can improve the therapeutic effect.

Olfactory Training for Postviral Olfactory Dysfunction: Systematic Review and Meta‐analysis

“…20,22-24,29-31 Although statistically significant improvements in TDI scores postintervention were reported in all studies except one, evidence supporting modification of odor concentrations, combinations, and molecular weight was mixed. 20,22-24,29,30 Increasing patient compliance and adherence through using patient-purchased essential oils or a more intuitive “olfactory training ball” showed more favorable results when compared with no intervention and COT, respectively. 23,31…”

“…MCID was defined as a .5.5 or .6 increase in TDI scores by the individual study authors. In 2006, Gudziol et al 33 demonstrated that an increase of 5.5 points in TDI composite scores corresponded to more than 60% of patients reporting subjective olfactory improvement; 4 studies use this value as 18 Prospective cohort study 39 COT 8 mo Gellrich et al (2018) 26 Prospective case-control study 61 COT 3 mo Hummel et al (2009) 16 Prospective cohort study 24 COT 3 mo Hummel et al (2017) 27 Retrospective cohort study 170 COT 3 mo Kollndorfer et al (2015) 17 Prospective cohort study 10 COT alone vs COT and vitamin A 3 mo Konstantinidis et al (2013) 28 Prospective cohort study 81 COT 4 mo Konstantinidis et al (2016) 19 Prospective cohort study 111 Short-term COT vs long-term COT 4 mo, 14 mo Oleszkiewicz et al (2018) 29 Prospective 20 Prospective cohort study 125 Combination 1 OT vs combination 2 OT 6 mo Saatci et al (2020) 31 Prospective cohort study 60 Olfactory training ball vs COT 3 mo…”

“…Longer durations were often associated with greater efficacy of OT. [18][19][20][21] Modified Olfactory Training…”

What to propose to treat post-viral non-conductive smell disorder in COVID-19? - systematic review with meta-analysis

“…However, of the 13 studies included in the qualitative analysis (table 2), ve studies were unique in their treatment [10,[21][22][23][24] and four did not have enough data for quantitative analysis (meta-analysis) [25][26][27][28]. Thus, four studies were selected for the meta-analysis involving 336 patients [29][30][31][32] (table 3). The entire article selection process is described in gure 1, which shows the PRISMA ow diagram for inclusion.…”

“…Outcome measures were determined by symptom scores and objective methods of olfactory testingwith the Sni n`Sticks test as the most common test used in the studies. Ten studies compared the mean TDI score ("T" -threshold, "D"discrimination, "I" -identi cation) before and after drug treatment in NCSD (total of six drugs) [10,[21][22][23][24][25][26][27][28], while four compared the mean TDI score before and after olfactory training in NCSD [29][30][31][32] (table 3). Of the studies with drug treatment, ve were the only ones for the drug they proposed to analyze (oral caroverine, oral vitamin A, intranasal insulin, intravenous pentoxifylline and oral lipoic acid) [10,21-24] and four were on intranasal sodium citrate [26][27][28]; however, studies with sodium citrate did not provide su cient pre-and posttreatment data for meta-analysis.…”