A new Cochrane review evaluated the effectiveness and safety of Chinese herbal medicines (CHM) in the treatment of menopausal symptoms. Its authors conducted a thorough search for randomised controlled trials (RCTs) comparing the effectiveness of CHM with placebo, hormone therapy (HT), pharmaceutical drugs, acupuncture, or another CHM formula in women suffering from menopausal symptoms.

Two review authors independently assessed 864 studies for eligibility. Data extractions were performed by them with disagreements resolved through group discussion and clarification of data or direct contact with the study authors. Data analyses were performed in accordance with Cochrane Collaboration guidelines.

In total, 22 RCTs (2902 women) could be included. When CHM was compared with placebo (8 RCTs), there was little or no evidence of a difference between the groups for the following outcomes: hot flushes per day (MD 0.00, 95% CI -0.88 to 0.89; 2 trials, 199 women; moderate quality evidence); hot flushes per day assessed by an overall hot flush score in which a difference of one point equates to one mild hot flush per day (MD -0.81 points, 95% CI -2.08 to 0.45; 3 RCTs, 263 women; low quality evidence); and overall vasomotor symptoms per month measured by the Menopause-Specific Quality of Life questionnaire (MENQOL, scale 0 to 6) (MD -0.42 points; 95% CI -1.52 to 0.68; 3 RCTs, 256 women; low quality evidence). In addition, results from individual studies suggested there was no evidence of a difference between the groups for daily hot flushes assessed by severity (MD -0.70 points, 95% CI -1.00, -0.40; 1 RCT, 108 women; moderate quality evidence); or overall monthly hot flushes scores (MD -2.80 points, 95% CI -8.93 to 3.33; 1 RCT, 84 women; very low quality evidence); or overall daily night sweats scores (MD 0.07 points, 95% CI -0.19 to 0.33, 1 RCT, 64 women; low quality evidence); or overall monthly night sweats scores (MD 1.30 points, 95% CI -1.76 to 4.36, 1 RCT, 84 women; very low quality evidence). However, one study reported that overall monthly vasomotor symptom scores were lower in the CHM group (MD -4.79 points, 95% CI -5.52 to -4.06; 1 RCT, 69 women; low quality evidence).

When CHM was compared with HT (10 RCTs), only two RCTs reported monthly vasomotor symptoms using MENQOL. It was uncertain whether CHM reduces vasomotor symptoms (MD 0.47 points, 95% CI -0.50 to 1.44; 2 RCTs, 127 women; very low quality evidence).

Adverse effects were not fully reported in the included studies. Adverse events reported by women taking CHM included mild diarrhoea, breast tenderness, gastric discomfort and an unpleasant taste. Effects were inconclusive because of imprecise estimates of effects: CHM versus placebo (RR 1.51; 95% CI 0.69 to 3.33; 7 trials, 705 women; I² = 40%); CHM versus HT (RR 0.96; 95% CI 0.66 to 1.39; 2 RCTs, 864 women; I² = 0%); and CHM versus specific conventional medications (such as Fluoxetine and Estazolam) (RR 0.20; 95% CI 0.03 to 1.17; 2 RCTs, 139 women; I² = 61%).

The authors concluded: We found insufficient evidence that Chinese herbal medicines were any more or less effective than placebo or HT for the relief of vasomotor symptoms. Effects on safety were inconclusive. The quality of the evidence ranged from very low to moderate; there is a need for well-designed randomised controlled studies.

This review seems well done and reports clear findings. The fact that there was insufficient evidence for CHM is probably no surprise to most readers of this blog. However, I would like to draw your attention to a finding that could easily be missed: most of the primary studies failed to mention adverse effects; to be perfectly clear: they did not state “there were no adverse effects”, but they simply did not mention the subject of adverse effects at all.

In my view, this is a breach of research ethics. I have been banging on about this phenomenon for some time now, because I think it is important. Many if not most clinical trials in this area neglect reporting adverse effects. This means that we get an entirely misleading impression about the safety of the treatments in question. Reviewers of such studies are bound to conclude that they seem to be safe, while, in fact, researchers have only been withholding crucial information from us.

The solution to this fast-growing problem would be simple: trialists must be forced to fully report adverse effects. This is less complicated that it might seem: journal editors must insist that all authors fully report adverse effects of alternative treatments. Even if there were none at all – a very unlikely proposition if you think about it – they must disclose this fact.

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