[Systematic review on methodology of randomized controlled trials of post-marketing Chinese patent drugs for treatment of type 2 diabetes].

BACKGROUND: Randomized controlled trial (RCT) is considered as the gold standard for the efficacy assessment of medicines. With the increasing number of Chinese patent drugs for treatment of type 2 diabetes, the methodology of post-marketing RCTs evaluating the efficacy and specific effect has become more important.

OBJECTIVE: To investigate post-marketing Chinese patent drugs for treatment of type 2 diabetes, as well as the methodological quality of post-marketing RCTs.

SEARCH STRATEGY: Literature was searched from the books of Newly Compiled Traditional Chinese Patent Medicine and Chinese Pharmacopeia, the websites of the State Food and Drug Administration and the Ministry of Human Resources and Social Security of the People's Republic of China, China National Knowledge Infrastructure Database, Chongqing VIP Chinese Science and Technology Periodical Database, Chinese Biomedical Database (SinoMed) and Wanfang Data. The time period for searching ran from the commencement of each database to August 2011.

INCLUSION CRITERIA: RCTs of post-marketing Chinese patent drugs for treatment of type 2 diabetes with intervention course no less than 3 months.

DATA EXTRACTION AND ANALYSIS: Two authors independently evaluated the research quality of the RCTs by the checklist of risk bias assessment and the data collection forms based on the CONSORT Statement. Independent double data-extraction was performed.

RESULTS: The authors identified a total of 149 Chinese patent drugs for treatment of type 2 diabetes. According to different indicative syndromes, the Chinese patent drugs can be divided into the following types, namely, yin deficiency and interior heat (n=48, 32%), dual deficiency of qi and yin (n=58, 39%) and dual deficiency of qi and yin combined with blood stasis (n=22, 15%). A total of 41 RCTs meeting the inclusion criteria were included. Neither multicenter RCTs nor endpoint outcome reports were found. Risk bias analysis showed that 81% of the included studies reported randomization for grouping without sequence generation, 98% of these studies did not report concealment of random numbers, 5% used placebo, 10% reported outcome attrition bias and no study employed the analysis of intention-to-treat and 98% reported the diagnostic criteria for type 2 diabetes. The participants mainly consisted of outpatients without complications (76%). The minimum and maximum sample size was 40 and 300 (106 ± 60), respectively.

CONCLUSION: The inclusion and exclusion criteria and outcome measures did not match the purposes and contents of post-marketing research in the included studies. They also failed to reflect the basic principles of traditional Chinese medicine in the process of diagnosis and treatment. The demographic characteristics of the patients, the indications for medicine and the syndrome differentiation process were not reported sufficiently and transparently. In order to improve the post-marketing research and promote the rational use of Chinese patent drugs, it is recommended that phase IV clinical trials should establish clear research purpose as well as hypothesis first, and choose scientific and evidence-based study design and outcome measures. In addition, guidelines for implementation of post-marketing research should be developed.