We thank Dr. Chrubasik for her comments. The point of clinical heterogeneity is important in the context of meta-analyses. Most authors are well aware of it and try to deal with it in the most appropriate way. Clinical heterogeneity in conventional trials can be caused by a range of factors, such as differences in patient samples or treatment regimen. In studies of herbal medicines, heterogeneity can be caused by the additional factor of extract quality. It is essential that researchers and, more importantly, clinicians are aware that extracts are not necessarily identical and that even batch-to-batch variations can be considerable. In meta-analyses like ours, such variations distort the overall effect and could generate a false-negative result. Our results suggest differential treatment effects in favor of hawthorn extract, and one might speculate that the effects are even greater if only the optimal extract and dosage are administered.
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© 2003 Excerpta Medica Inc. Published by Elsevier Inc. All rights reserved.
