REPORTING OF ASSIGNMENT METHODS IN CLINICAL-TRIALS

A stratified random sample of the reports of 200 clinical trials, conducted in the 1980s, listed in the February 1991 issue of Controlled Clinical Trials, was reviewed. The four strata were small single-center trials (SST), small multicenter trials (SMT), large single-center trials (LST), and large multicenter trials (LMT). The description of the assignment method in the published reports of the results of the trials was classified into four categories: good description (G), provides details; fair description (F), describes some details; poor description (P), only states that randomization was used; and no description (N). The percentage of good and fair descriptions among the four strata were: (Graphics) The proportion of G or F trials is slightly higher in the LST because one third used systematic rather than random assignment, which is easier to describe. Good descriptions usually require only two or three lines of text, and yet the description of the randomization method for most clinical trials is so poor that the reader cannot tell if randomization has been applied properly.