Chinese Medicinal Herbs in the Treatment of Upper Airway Cough Syndrome: A Systematic Review of Randomized, Controlled Trials

Hongli Jiang, Wei Liu, Guanhong Li, Tao Fan, Bing Mao
Altern Ther Health Med. 2016 Mar;22(3):38-51.
Abstract
Context Upper airway cough syndrome (UACS), previously called postnasal drip syndrome (PNDS), has been considered universally to be one of the most common causes of chronic cough. As an important part of complementary and alternative therapy, traditional Chinese medicine (TCM) has found an exact curative therapy for chronic cough through clinical practice for thousands of years. Objective The aim of the current review was to investigate systematically the beneficial and adverse effects of Chinese medicinal herbs (CMH) in the treatment of UACS. Design The research team performed searches in 11 main databases from respective inception to October 31, 2015, supplemented with manual retrieval of other data. Only randomized, controlled trials (RCTs) reporting on the effectiveness of CMH in patients with UACS were included. Descriptive and quantitative data on the studies' designs, population demographics, interventions, outcomes, and methodological quality were extracted and tabulated. Methodological quality was assessed using the Cochrane risk-of-bias system and the quality of the evidence was evaluated using the Grades of Recommendation Assessment, Development, and Evaluation (GRADE) system. Participants The reviewed studies included 1355 participants-720 in the CMH groups and 635 in the control groups-of both genders, from various professional and ethnic groups, and with a wide range of ages. They all had a duration of cough symptoms of longer than 8 wk and a clinical diagnosis of chronic cough induced by UACS that was supported by appropriate physical findings.

Outcome Measures The primary outcomes included (1) TCM recovery rate and (2) TCM cough symptom score. TCM's curative effect was calculated as the cumulative percentage of the symptom-score reduction (PSSR), estimated between baseline and postintervention. The cough symptom scores were graded according to the Chinese Criteria Guiding Principle of Clinical Research on New Drugs of TCM, with the scores being classified into 4 grades. Those scores ranged from 0-3 (ie, 0, 1, 2, 3, respectively), or 0-9 (ie, 0, 3, 6, 9, respectively), with the higher scores signifying a more frequent and severe cough. Results A total of 16 studies that had been published in Chinese journals was ultimately identified for the review. The majority of methodological judgments demonstrated an unclear risk of bias. A meta-analysis was conducted using a random effects model due to the poor homogeneity of the studies. Compared with Western medicine (WM), patients in both the CMH groups and the integrated therapy groups showed (1) a higher TCM recovery rate; (2) better relief of primary symptoms, including cough and postnasal dripping; (3) a reduction in physical signs, including the cobblestone appearance of the oropharyngeal mucosa or mucus in the oropharynx; and (4) a lower risk of cough relapse. No severe adverse events occurred in either group. Conclusions CMH may be a safe and effective alternative for the treatment of UACS. The study highlighted the paucity of reliable clinical evidence for CMH and the need for RCTs of higher quality in the future.