Objectives: To generate information about what types of articles have been published in what languages on what topics. In addition, we assessed the methodological quality of randomized clinical trials (RCTs) over time.
Methods: Searches were carried out in Medline in order to (a) identify the number of articles published in English, Chinese, German, Russian, and Japanese during the years 1977, 1987, 1997, and 2007; (b) identify the number of five types of articles, namely, systematic reviews (SRs), reviews, clinical controlled trials (CCTs), RCTs, and case reports, published in the above-mentioned 4 years; (c) identify the types of herbal medicine that were most frequently tested in CCTs and RCTs. Twenty RCTs were retrieved from each of the above-mentioned 4 years and were quality assessed using Jadad score and were statistically compared.
Results: (1) The number of articles on herbal medicine has increased during the last three decades. (2) Review articles and RCTs were the most numerous types of publications toward the end of our observation period; CCTs were the least. (3) Guar gum, evening primrose oil, ginseng, and Ginkgo biloba were some of the main herbal medicines that were most frequently submitted to CCTs and RCTs. (4) The average Jadad score improved continually (F = 6.27, p = .014) between 1977 and 2007.
Conclusion: These findings are consistent with the notion that the quantity and quality of RCTs of herbal medicine have been improving during the last three decades. We suggest that the adaption of the herbal-medicine-specific Consolidated Standard of Reporting Trials guidelines might further improve the situation in future.