Generally speaking, Cochrane reviews provide the best (most rigorous, transparent and independent) evidence on the effectiveness of medical or surgical interventions. It is therefore important to ask what they tell us about homeopathy. In 2010, I did exactly that and published it as an overview of the current best evidence. At the time, there were 6 relevant Cochrane reviews. They covered the following conditions: cancer, attention-deficit hyperactivity disorder, asthma, dementia, influenza and induction of labour. And their results were clear: they did not show that homeopathic medicines have effects beyond placebo.
Now a further Cochrane review has been published.
Does it change this situation?
This systematic review assessed the effectiveness and safety of oral homeopathic medicinal products compared with placebo or conventional therapy to prevent and treat acute respiratory tract infections (ARTIs) in children. The researchers conducted extensive literature searches, checked references, and contacted study authors to identify additional studies. They included all double-blind, randomised controlled trials (RCTs) or double-blind cluster-RCTs comparing oral homeopathy medicinal products with identical placebo or self selected conventional treatments to prevent or treat ARTIs in children aged 0 to 16 years.
Eight RCTs of 1562 children receiving oral homeopathic medicinal products or a control treatment (placebo or conventional treatment) for upper respiratory tract infections (URTIs). Four treatment studies examined the effect on recovery from URTIs, and four studies investigated the effect on preventing URTIs after one to three months of treatment and followed up for the remainder of the year. Two treatment and two prevention studies involved homeopaths individualising treatment for children. The other studies used predetermined, non-individualised treatments. All studies involved highly diluted homeopathic medicinal products.
Several key limitations to the included studies were identified, in particular methodological inconsistencies and high attrition rates, failure to conduct intention-to-treat analysis, selective reporting, and apparent protocol deviations. The authors deemed three studies to be at high risk of bias in at least one domain, and many had additional domains with unclear risk of bias. Three studies received funding from homeopathy manufacturers; one reported support from a non-government organisation; two received government support; one was co-sponsored by a university; and one did not report funding support.
Methodological inconsistencies and significant clinical and statistical heterogeneity precluded robust quantitative meta-analysis. Only four outcomes were common to more than one study and could be combined for analysis. Odds ratios (OR) were generally small with wide confidence intervals (CI), and the contributing studies found conflicting effects, so there was little certainty that the efficacy of the intervention could be ascertained.
All studies assessed as at low risk of bias showed no benefit from oral homeopathic medicinal products; trials at uncertain and high risk of bias reported beneficial effects. The authors found low-quality evidence that non-individualised homeopathic medicinal products confer little preventive effect on ARTIs (OR 1.14, 95% CI 0.83 to 1.57). They also found low-quality evidence from two individualised prevention studies that homeopathy has little impact on the need for antibiotic usage (N = 369) (OR 0.79, 95% CI 0.35 to 1.76).
The authors also assessed adverse events, hospitalisation rates and length of stay, days off school (or work for parents), and quality of life, but were not able to pool data from any of these secondary outcomes. There is insufficient evidence from two pooled individualised treatment studies (N = 155) to determine the effect of homeopathy on short-term cure (OR 1.31, 95% CI 0.09 to 19.54; very low-quality evidence) and long-term cure rates (OR 1.01, 95% CI 0.10 to 9.96; very low-quality evidence). Adverse events were reported inconsistently; however, serious events were not reported. One study found an increase in the occurrence of non-severe adverse events in the treatment group.
The authors concluded that pooling of two prevention and two treatment studies did not show any benefit of homeopathic medicinal products compared to placebo on recurrence of ARTI or cure rates in children. We found no evidence to support the efficacy of homeopathic medicinal products for ARTIs in children. Adverse events were poorly reported, so conclusions about safety could not be drawn.
In their paper, the authors state that “there are no established explanatory models for how highly diluted homeopathic medicinal products might work. For this reason, homeopathy remains highly controversial because the key concepts governing this form of medicine are not consistent with the established laws of conventional therapeutics.” In other words, there is no reason why highly diluted homeopathic remedies should work. Yet, remarkably, when asked what conditions responds best to homeopathy, most homeopaths would probably include ARTI of children.
The authors also point out that “The results of this review are consistent with all previous systematic reviews on homeopathy. Funders and study investigators contemplating any further research in this area need to consider whether further research will advance our knowledge, given the uncertain mechanism of action and debate about how the lack of a measurable dose can make them effective. The studies we identified did not use a uniform approach to choosing and measuring outcomes or assigning appropriate time points for outcome measurement. The use of validated symptom scales would facilitate future meta-analyses. It is unclear if there is any benefit from individualised (classical) homeopathy over the use of commercially available products.”
Even though I agree with the authors on most of their views and comment their excellent work, I would be more outspoken regarding the need of further research. In my view, it would be a foolish, wasteful and therefore unethical activity to fund, plan or conduct further research in this area.