Can Sodium Citrate Effectively Improve Olfactory Function in Non-Conductive Olfactory Dysfunction?

Abstract

The objective of this study was to perform a systematic review of the literature for application of intranasal sodium citrate in the patients with olfactory dysfunction to help determine the sodium citrate treatments for this condition. Two authors independently searched the data base (Medline, Scopus, and the Cochrane database) for relevant studies from inception to January 2018. Included studies were randomized controlled studies published in English comparing topical sodium citrate application (treatment group) with saline (control group) in patients who had olfactory dysfunction. Outcomes of interest included the change of olfactory identification and threshold during 2 hours post-treatment. Three studies were enrolled in the meta-analysis. Compared with control group, treatment group did not increase posttreatment score of olfactory identification [standardized mean difference (SMD)=-0.03; 95% confidence interval (CI)= -0.29-0.24; I2=0%] and olfactory threshold (SMD=0.18; 95% CI=-0.09-0.45; I2=0%) significantly. In the degree of pre-post improvement of two outcomes, although treatment group statistically showed the significant improvement in olfactory threshold (SMD=0.30; 95% CI=0.05- 0.55; I2=17%), the clinical significance of this outcome was meaningless. Similarly, there was no significant difference in olfactory identification between two groups (SMD=0.17; 95% CI=-0.11-0.45; I2=22%). Unlike the recent favorable results, our summated results presented the uselessness for the local application of sodium citrate in improving patient’s olfactory function. However, we also had some limitation such as small sample size and inconsistent application methods. Therefore, larger trials and standardized methodology are needed to reach more stronger and exact results. Key words: Meta-analysis ㆍ Olfactory dysfunction ㆍ Olfactory identification ㆍ Olfactory threshold ㆍ Sodium citrate