Prospective Registration and Outcome-Reporting Bias in Randomized Controlled Trials of Eczema Treatments: A Systematic Review

We assessed completeness of trial registration and the extent of outcome-reporting bias in published randomized controlled trials (RCTs) of eczema (atopic dermatitis) treatments by surveying all relevant RCTs published from January 2007 to July 2011 located in a database called the Global Resource of Eczema Trials (GREAT). The GREAT database is compiled by searching six bibliographic databases, including EMBASE and MEDLINE. Out of 109 identified RCTs, only 37 (34%) had been registered on an approved trial register. Only 18 out of 109 trials (17%) had been registered "properly" in terms of submitting the registration before the trial end date and nominating a primary outcome. The proportion of "any registered" and "properly registered" RCTs increased from 19% and 10% in 2007 to 57% and 36% in 2011, respectively. Assessment of selective outcome-reporting bias was difficult even among the properly registered trials owing to unclear primary outcome description especially with regard to timing. Only 5 out of the 109 trials (5%) provided enough information for us to be confident that the outcomes reported in the published trial were consistent with the original registration. Adequate trial registration and description of primary outcomes for eczema RCTs is currently poor.