Artículo
en Inglés
| LILACS, SES-SP | ID: biblio-1139690
ABSTRACT
BACKGROUND:
The authors of randomized controlled trials will usually claim that they have met the randomization process criterion. However, sequence generation schemes differ and some schemes that are claimed to be randomized are not genuinely randomized. Even less well understood, and often more difficult to ascertain, is whether the allocation was really concealed.
The risk of selection bias in 1,714 records indexed in Medline database up to 2018 was assessed, independent of language and access. Two dimensions implicated in the allocation were considered generation of the allocation sequence; and allocation concealment.
RESULTS:
We included 420 randomized controlled trials and all of them were evaluated to detect selection bias. In the sample studied, only 28 properly controlled the selection bias. Lack of control over selection bias was present in 80% of the studies evaluated in both groups.