Validity of randomized clinical trials in Gastroenterology from 1964–2000

The internal validity of clinical trials depends on the adequacy of the reported methodological quality. We assessed the methodological quality of all 383 randomized clinical trials published in Gastroenterology as original articles from 1964 to 2000. The methodological quality (randomization and blinding), sample size, publication year, and disease area were extracted from each trial. Changes during the study period were analyzed by analysis of variance with adjustments for potential confounders. Forty-two percent of all trials reported adequate generation of the allocation sequence, 39% reported adequate allocation concealment, and 62% were double blind. The reported methodological quality improved significantly in the mid-1990s. Conclusions: The present study shows a positive development, but the reported methodological quality of trials can still be improved.