Article type
Year
Abstract
Introduction/Objective: To determine whether clinical trials originating in certain countries always have positive results.
Methods: Data sources: Abstracts of trials from Medline (January 1966 - June 1995). Study selection: Two separate studies were conducted. The first included trials where the clinical outcome of a group of subjects receiving acupuncture was compared to that of a group receiving placebo, no treatment or a non-acupuncture intervention. In the second study, randomized or controlled trials of interventions other than acupuncture published in China, Japan, Russia/USSR or Taiwan were compared to those published in England. Data extraction: Blinded reviewers determined inclusion and outcome and separately classified each trial by country of origin.
Results: In the study of acupuncture trials, 252 of 1085 abstracts met the inclusion criteria. Research conducted in certain countries was uniformly favorable to acupuncture: all trials originating from China, Japan, Hong Kong and Taiwan were positive as were 10 out of 11 of those published in Russia/USSR. In study that examined interventions other than acupuncture, 405 of 1100 abstracts met the inclusion criteria. Of trials published in England, 75% gave the test treatment as superior to control. The results for China, Japan, Russia/USSR and Taiwan were 99%, 89%, 97% and 95% respectively. No trials published in China or Russia/USSR found a test treatment to be ineffective.
Discussion: Some countries publish unusually high proportions of positive results. Publication bias is a possible explanation. Researchers undertaking systematic reviews should consider carefully how to manage data from these countries.
Methods: Data sources: Abstracts of trials from Medline (January 1966 - June 1995). Study selection: Two separate studies were conducted. The first included trials where the clinical outcome of a group of subjects receiving acupuncture was compared to that of a group receiving placebo, no treatment or a non-acupuncture intervention. In the second study, randomized or controlled trials of interventions other than acupuncture published in China, Japan, Russia/USSR or Taiwan were compared to those published in England. Data extraction: Blinded reviewers determined inclusion and outcome and separately classified each trial by country of origin.
Results: In the study of acupuncture trials, 252 of 1085 abstracts met the inclusion criteria. Research conducted in certain countries was uniformly favorable to acupuncture: all trials originating from China, Japan, Hong Kong and Taiwan were positive as were 10 out of 11 of those published in Russia/USSR. In study that examined interventions other than acupuncture, 405 of 1100 abstracts met the inclusion criteria. Of trials published in England, 75% gave the test treatment as superior to control. The results for China, Japan, Russia/USSR and Taiwan were 99%, 89%, 97% and 95% respectively. No trials published in China or Russia/USSR found a test treatment to be ineffective.
Discussion: Some countries publish unusually high proportions of positive results. Publication bias is a possible explanation. Researchers undertaking systematic reviews should consider carefully how to manage data from these countries.