Clinical Evidence of Chinese Herbal Medicine for Treatment of Idiopathic Sudden Sensorineural Hearing Loss from Chinese Literature

Purpose: To provide a comprehensive summary of all clinical evidence on Chinese herbal medicine (CHM) for idiopathic sudden sensorineural hearing loss (ISSHL) published in Chinese literature. Methods: We systematically searched randomized clinical trials (RCTs), clinical controlled trials (CCTs), case series (CSs) and case reports (CRs) which reported CHM for ISSHL through four main Chinese electronic databases from their inception to March 2014. We bibliometrically analyzed the studies and assessed themethodological quality of RCTsusing the Cochrane risk of bias tool. Results: A total of 299 clinical studies with involving 22,237 participants were identified including 150 RCTs, 42 CCTs, 80 CSs and 27 CRs. The number of publications increased obviously per year from 1995, with the peak in 2011. Among 145 different herbal formulae tested, the most popular prescribed herbal formulae were Longdan Xiegan decoction and TongqiaoHuoxue decoction, and the top three frequently used Chinese herbs were Rhizoma Chuanxiong, Radix Bupleuri and Radix Puerariae Lobatae. The most frequently reported outcome was improvement of hearing in 286 (95.7%), followed by improvement of tinnitus (139, 46.5%), improvement of dizziness (99, 33.1%). Among the 150 RCTs, randomizationmethods were described in only 12 trials (8.0%). No trial reported allocation concealment and only four mentioned blinding. Among 146 RCTs (97.3%) and 37 CCTs (88.1%) reporting improvement of hearing as the outcome measurement, all showed significant difference favoring CHM. Of 16 trials reporting adverse events, only five trials reported mild adverse events related to CHM and the remaining stated that none had occurred. Conclusion: The quantity of clinical research on CHM for ISSHL is substantial, but methodological quality of RCTs is generally suboptimal. Future clinical studies would need to report structurally and based on the CONSORT and TREND Statements. Quality of life, adverse events, depression and anxiety should be addressed as outcome measures. Contact: Chun-Xiang Su, susu18182004@126.com Corresponding Author: Jian-Ping Liu (Center for Evidence-Based Chinese Medicine, Beijing University of Chinese Medicine, Chaoyang District, Beijing 100029, China), jianping l@hotmail.com