PMC:7558914 / 17572-17745 JSONTXT

{"project":"LitCovid-sentences","denotations":[{"id":"T117","span":{"begin":0,"end":173},"obj":"Sentence"}],"namespaces":[{"prefix":"_base","uri":"http://pubannotation.org/ontology/tao.owl#"}],"text":"Despite these results, these studies had severe methodological limitations, such as lack of randomization, lack of covariate-adjusted analysis, and potential selection bias."}