PMID- 22500409
OWN - NLM
STAT- MEDLINE
DCOM- 20131230
LR  - 20161018
IS  - 1003-5370 (Print)
IS  - 1003-5370 (Linking)
VI  - 32
IP  - 1
DP  - 2012 Jan
TI  - [An investigation of the statistical power of the effect size in randomized 
      controlled trials for the treatment of patients with type 2 diabetes mellitus 
      using Chinese medicine].
PG  - 119-23
AB  - OBJECTIVE: To investigate whether the power of the effect size was based on 
      adequate sample size in randomized controlled trials (RCTs) for the treatment of 
      patients with type 2 diabetes mellitus (T2DM) using Chinese medicine. METHODS: 
      China Knowledge Resource Integrated Database (CNKI), VIP Database for Chinese 
      Technical Periodicals (VIP), Chinese Biomedical Database (CBM), and Wangfang Data 
      were systematically recruited using terms like "Xiaoke" or diabetes, Chinese 
      herbal medicine, patent medicine, traditional Chinese medicine, randomized, 
      controlled, blinded, and placebo-controlled. Limitation was set on the 
      intervention course > or = 3 months in order to identify the information of 
      outcome assessement and the sample size. Data collection forms were made 
      according to the checking lists found in the CONSORT statement. Independent 
      double data extractions were performed on all included trials. The statistical 
      power of the effects size for each RCT study was assessed using sample size 
      calculation equations. RESULTS: (1) A total of 207 RCTs were included, including 
      111 superiority trials and 96 non-inferiority trials. (2) Among the 111 
      superiority trials, fasting plasma glucose (FPG) and glycosylated hemoglobin 
      HbA1c (HbA1c) outcome measure were reported in 9% and 12% of the RCTs 
      respectively with the sample size > 150 in each trial. For the outcome of HbA1c, 
      only 10% of the RCTs had more than 80% power. For FPG, 23% of the RCTs had more 
      than 80% power. (3) In the 96 non-inferiority trials, the outcomes FPG and HbA1c 
      were reported as 31% and 36% respectively. These RCTs had a samples size > 150. 
      For HbA1c only 36% of the RCTs had more than 80% power. For FPG, only 27% of the 
      studies had more than 80% power. CONCLUSIONS: The sample size for statistical 
      analysis was distressingly low and most RCTs did not achieve 80% power. In order 
      to obtain a sufficient statistic power, it is recommended that clinical trials 
      should establish clear research objective and hypothesis first, and choose 
      scientific and evidence-based study design and outcome measurements. At the same 
      time, calculate required sample size to ensure a precise research conclusion.
FAU - Ma, Li-Xin
AU  - Ma LX
AD  - Centre for Evidence-Based Chinese Medicine, Beijing University of Chinese 
      Medicine, Beijing.
FAU - Liu, Jian-Ping
AU  - Liu JP
LA  - chi
PT  - English Abstract
PT  - Journal Article
PT  - Meta-Analysis
PT  - Research Support, U.S. Gov't, Non-P.H.S.
PL  - China
TA  - Zhongguo Zhong Xi Yi Jie He Za Zhi
JT  - Zhongguo Zhong xi yi jie he za zhi Zhongguo Zhongxiyi jiehe zazhi = Chinese 
      journal of integrated traditional and Western medicine
JID - 9211576
RN  - 0 (Drugs, Chinese Herbal)
SB  - IM
MH  - Diabetes Mellitus, Type 2/*drug therapy
MH  - Drugs, Chinese Herbal/*therapeutic use
MH  - Humans
MH  - Medicine, Chinese Traditional
MH  - *Phytotherapy
MH  - Randomized Controlled Trials as Topic
MH  - Research Design
MH  - Sample Size
EDAT- 2012/04/17 06:00
MHDA- 2014/01/01 06:00
CRDT- 2012/04/17 06:00
PHST- 2012/04/17 06:00 [entrez]
PHST- 2012/04/17 06:00 [pubmed]
PHST- 2014/01/01 06:00 [medline]
PST - ppublish
SO  - Zhongguo Zhong Xi Yi Jie He Za Zhi. 2012 Jan;32(1):119-23.