Efficacy and safety of Sanfeng Tongqiao Diwan in the treatment of upper airway cough syndrome: a randomized, double-blind, placebo-controlled clinical study

Background: Sanfeng Tongqiao Diwan has shown the potential to alleviate acute, recurrent, and chronic rhinitis in adults based on available studies. However, the evidence for its application in upper airway cough syndrome (UACS) is unclear. The purpose of this study was thus to investigate the efficacy and safety of Sanfeng Tongqiao Diwan in the treatment of UACS. Methods: This was a single-center, randomized, double-blind, placebo-controlled clinical trial. A total of 60 patients who satisfied the inclusion criteria were randomly divided into experimental and placebo groups in a 1:1 ratio. The experimental group was given Sanfeng Tongqiao Diwan, and the placebo group was given a simulant for 14 consecutive days. The follow-up period was 15 days. The primary outcome was the total effective rate. The secondary outcomes included clinical efficacy, visual analogue scale (VAS) of related symptoms, and Leicester Cough Questionnaire in Mandarin-Chinese (LCQ-MC) scores before and after the treatment. Additionally, the safety was also evaluated. Results: The total effective rate in the experimental group was 86.6% (26/30), which was significantly higher than the 7.1% (2/28) in the placebo group (difference 79.6; 95% CI: 57.0 to 89.1; P<0.001). Nasal congestion, runny nose, cough, postnasal drip, and overall symptoms in the experimental group were significantly lower than those in the placebo group after treatment (3.7 +/- 1.5 vs. 5.0 +/- 1.1, 3.6 +/- 1.3 vs. 5.9 +/- 1.1, 3.8 +/- 1.2 vs. 6.8 +/- 1.3, 3.5 +/- 1.4 vs. 6.1 +/- 1.5, 3.8 +/- 2.0 vs. 7.3 +/- 1.4, respectively; all P values <0.001). After treatment, the LCQ-MC score in the experimental group was significantly higher than that in the placebo group (all P values <0.001). The blood eosinophil count in the placebo group was significantly higher after treatment than before treatment (P=0.037). No abnormalities were found in liver or renal indicators during the treatment period in the 2 groups, and no adverse reactions occurred. Conclusions: Sanfeng Tongqiao Diwan improved the symptoms and living quality of patients with UACS and showed acceptable safety. The results of this trial represent rigorous clinical evidence for the application of Sanfeng Tongqiao Diwan and further support a new option in UACS treatment.