AIM: To investigate whether the difference of amlodipine's anti-hypertensive effects between
experimental agent groups and
reference agent groups.METHODS: Searching China Hospital Knowledge Database to screen the randomizative clinical trials on amlodipine's anti-hypertension in Chinese.Allocating the matching trials including two type trials of amodipine where the drug is
experimental agent in one type trials and reference agent in other type,but the dose,period of treatment are alike in the two type trials.Analyzing and comparing the anti-hypertensive effects between two type trials.RESULTS: 19 matching trials had been made,including 10 trials where the amlodipine was the experimental agent and 9 trials where reference agent.The weighted averages of total effective rate of the experimental groups was(88.57)% and the reference groups's was(79.34)%.The Ridit value was(0.5411) and(0.4370) in the two groups.The rank sum test indicated that the total effective rate and the Ridit value were difference between 10 experimental groups and 9 reference groups(P<(0.01)).CONCLUSION:The effects of experimental agent groups are over-estimated and/or the reference groups's are underrated.We must pay attention to the group bias in the clinical trial of new drug and in the Meta analysis