EvaluatingConcordanceofBodiesofEvidence fromRandomizedControlledTrials,DietaryIntake, andBiomarkersofIntakeinCohortStudies: AMeta-EpidemiologicalStudy

Abstract

Weaimedtoidentifyandcompareempiricaldatatodeterminetheconcordanceofdiet–diseaseeffectestimatesofbodiesofevidence(BoE)from randomized controlled trials (RCTs), dietary intake, and biomarkers of dietary intake in cohort studies (CSs). The Cochrane Database of Systematic Reviews and MEDLINE were searched for systematic reviews (SRs) of RCTs and SRs of CSs that investigated both dietary intake and biomarkers of intake published between 1 January 2010 and 31 December 2019. For matched diet–disease associations,the concordancebetween resultsfrom the 3 different BoE was analyzed using 2 definitions: qualitative (e.g., 95% CI within a predefined range) and quantitative (test hypothesis on the z score). Moreover, the differences in the results coming from BoERCTs, BoECSsdietaryintake, and BoECSsbiomarkers were synthesized to get a pooled ratio ofriskratio(RRR)acrossalleligiblediet–diseaseassociations,soastocomparethe3BoE.Overall, 49diet–diseaseassociationsderivedfrom41SRs were identified and included in the analysis. Twenty-four percent, 10%, and 39% of the diet–disease associations were qualitatively concordant comparing BoERCTs with BoECSsdietaryintake, BoERCTs with BoECSsbiomarkers, and comparing both BoE from CSs, respectively; 88%, 69%, and 90% of the diet–disease associations were quantitatively concordant comparing BoERCTs with BoECSsdietaryintake, BoERCTs with BoECSsbiomarkers, and comparing both BoE from CSs, respectively. The pooled RRRs comparing effects from BoERCTs with effects from BoECSsdietaryintake were 1.09 (95% CI: 1.06, 1.13) and1.18(95%CI:1.10,1.25)comparedwithBoECSsbiomarkers.ComparingbothBoEfromCSs,thedifferenceintheresultswasalsosmall(RRR:0.92;95% CI: 0.88, 0.96). Our findings suggest that BoE from RCTs and CSs are often quantitatively concordant. Prospective SRs in nutrition research should include, whenever possible, BoE from RCTs and CSs on dietary intake and biomarkers of intake to provide the whole picture for an investigated diet–diseaseassociation