More emphasis should be placed on the monitoring and reporting of adverse events to justify the safety of herbs in clinical trials in the future

Our review revealed the lack of evidence for clinical use and policy making of Chinese herbs for H1N1 influenza in China. There is still a long way to go for evidence-based practice of TCM. In addition, our review found inadequate reporting on adverse events in the included trials. Eleven trials did not mention whether they had monitored adverse effects at all. Conclusions about the safety of herbal medicines cannot be drawn from this review due to the limited, inadequate recording and reporting of adverse events. Even for the trials that reported adverse events, their report was very brief, providing limited information. In China, there is a general perception that it is safe to use herbal medicines for various conditions. However, with the increasing reports of liver toxicity and other adverse events associated with Chinese herbal medicines. The funnel plot analysis showed asymmetry which suggests the possibility of publication bias of Chinese herbs for H1N1 influenza. Almost all the trials claimed positive effect of Chinese herbs though some of them turned out to be negative when analyzed by standard statistical techniques using risk ratios or mean differences. We undertook extensive searches for unpublished material, but found no unpublished ‘negative’ studies as in previous study. We thought this might be attributed to the lack of awareness to register clinical trials in China, the rejection of journal editors to negative trials, and the inaccessibility to unpublished data. We hope that with increasing awareness of prospective registration of clinical trials, publication of clinical trial protocol and reporting of negative clinical trials, the picture may change in the future. The mechanism of Chinese herbs in the treatment of influenza is complex. In traditional Chinese medicine, H1N1 influenza belongs to the scope of ‘cold’. In TCM, cold is differentiated into two types: Wind-cold Syndrome and Windheat Syndrome. The principles behind treating these two types were different. Generally speaking, the principles behind treating wind-cold syndrome are to: relieve external symptoms with drugs which are pungent in flavour and warm in property; ventilate the lungs and expel the pathogenic cold. The principles behind treating wind-heat syndrome are to: relieve external symptoms with drugs which are pungent in flavour and cool in property and promote the dispersing function of the lungs and clear up pathogenic wind heat. In addition, previous studies showed that administration of some Chinese herbs may have beneficial immunomodulatory effects for rapid recovery of viral infections. However, in this review, it seems that compared with oseltamivir, Chinese herbs might have better potential effects on fever solution than viral shedding, which suggested that most of Chinese herbs might not act as an antiviral. Last but not least, there is a lack of information about quality control for the development of the herbal preparations or for the manufacture of the herbal Ruxolitinib products, which is a quite common problem in Chinese clinical trials.

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