ReproducibilityofAPosterioriDietaryPatterns acrossTimeandStudies:AScopingReview

Abstract

Fewstudieshaveconsideredifaposterioridietarypatterns(DPs)aregeneralizableacrossdifferentcentersorstudies,oriftheyareconsistentlyseen overtime.Todate,nosystematicsearchoftheliteratureonthesetopicshasbeencarriedout.Ascopingreviewwasconductedthroughasystematic searchonthePubMeddatabase.Inthecurrentreview,weincludedthe34articlesexaminingtheextenttowhichaposterioriDPswereconsistently seen:1)acrosscentersfromthesamestudyoracrossdifferentstudiespotentiallyrepresentingdifferentpopulationsorcountries(hereindicatedas cross-study reproducibility) and 2) over longer time periods (i.e.,≥2 y) (here indicated as stability over time). Selected articles (published in 1981– 2019, 32% from 2010 onwards) were based on observational studies, mostly from Europe and North America. Five articles were based on children and/oradolescentsand14articlesincludedadults(2men;12women,ofwhom3werepregnantwomen).AposterioriDPsweremostlyderived(32 articles)withprincipalcomponentsorfactoranalyses.Amongthe9articlesassessingDPreproducibilityacrossstudies(numberofcenters/studies: 2–27;median:3),5providedaformalassessmentusingstatisticalmethods(4index-basedapproachesofdifferentcomplexity,1statisticalmodel). A median of 4 DPs was reproduced across centers/studies (range: 1–7). Among the 25 articles assessing DP stability over time (number of timeoccasions: 2–6; median: 3), 19 provided a formal assessment with statistical methods (17 index-based and/or test-based approaches, 1 statistical model, 1 with both strategies). The number and composition of DPs remained mostly stable over time. Based on the limited evidence collected, mostidentifiedDPsshowedgoodreproducibilityacrossstudiesandstabilityovertime.However,whenpresentwithinthesinglestudies,thecriteria fortheformalassessmentofcross-studyreproducibilityorstabilityovertimeweregenerallyverybasic