Lyng, Nina

Hvor nøjagtigt rapporterer elever fra 5. klasse deres indtag af madpakker og skolemad Baggrund Elever indtager mere end en tredjedel af deres daglige energi i skoletiden, hvoraf frokosten udgør det største bidrag. I Danmark spiser eleverne oftest medbragte madpakker, men samtidig fremhæves skolemad som en strukturel indsats, der kan fremme sunde vaner. Hovedparten af de eksisterende valideringsstudier af svarnøjagtigheden i elevers frokostindtag er gennemført i USA baseret på 24h recall, hvor svarnøjagtighed er valideret ved hjælp af direkte observation, mens resten af dagens indtag er baseret på selvrapportering. Analytisk kan svarnøjagtighed opdeles i matches, dvs. fødevarer, der ifølge en objektive metode er korrekt rapporteret; omissionsbeskriver fødevarer, der udeladt/glemt i rapportering, men ifølge den objektive metode er konsumeret og intrusions eller fantomfødevarer er rapporteret konsumeret men ifølge en objektiv metode slet ikke er serveret (konfabulation) eller serveret og ikke spist (stretch). Både 24h recall og direkte observation er tidskrævende og omkostningstunge at gennemføre, så der er behov for at videreudvikle eksisterende metoder til store populationer. Resultater fra USA kan ikke overføres direkte til en dansk kontekst, og der kun sparsom viden om, hvor nøjagtigt elever rapporterer indtag af madpakker. Afhandlingen bygger på en grundlæggende præmis om, at elever har den mest nøjagtige viden om, hvad de har spist, og det er derfor en forskningsmæssig opgave at udvikle valide metoder, der er tilpasset til deres kognitive forudsætninger. Formål Formålet med nærværende afhandling er at vurdere svarnøjagtigheden selvrapporteret indtag af madpakker og skolemad på fødevareniveau blandt eleveri 5. klasse. Formålet er operationaliseret til fire specifikke delformål: 1. At identificere fødevarer, der korrelerer med madpakke- og skolemadsformatet (Baggrundsanalyser). 2. At sammenligne svarnøjagtighed i selvrapporteret indtag af madpakker fordelt på køn og dataindsamlingsmetode (Artikel I). 3. At behandle aspekter af svar unøjagtigheder, der vedrører rapportering af fantomfødevarer herunder fejlrapportering fordelt på fødevaregruppe (Artikel II). 4. At sammenligne svarnøjagtighed i selvrapporteret skolefrokost fordelt på frokostformat (Artikel III). Materiale og metoder Nærværende studie blev gennemført som et selvrapporteret tværsnitsstudie. Populationen bestod af elever i 5. klasse fra 3 københavnske folkeskoler. Studiet strakte sig to dage, hvoraf eleverne spiste og rapporterede, hvad de spiste af madpakken den første dag. Næste dag fik eleverne serveret et valgfrit måltid skolemad, som de ligeledes rapporterede. Information om faktisk indtag blev indsamlet ved hjælp af et todelt spørgeskema. Den ene del bestod af et åbent spørgsmål, hvor eleverne med deres egne ord skulle beskrive, hvad de havde spist (OE-Q) og den anden del indeholdt en række prækodede spørgsmål (PC-Q). Herefter blev eleverne interviewet om deres faktiske indtag. Svarnøjagtigheden blev beregnet ved at sammenholde elevernes rapporterede indtag med en objektiv reference indsamlet ved hjælp at digitale billeder. Højde og vægt blev målt objektivt Rapporterede fødevarer blev kategoriseret i seks fødevaregrupper, der var baseret på empirisk viden om, hvad danske børn i den pågældende aldersgruppe spiste til frokost på hverdage. Svarnøjagtigheden blev bestemt i to trin. Først blev alle fødevarer klassificeret som matches, omissions og intrusions herunder konfabulationer og stretches. På baggrund heraf blev procentandelen af nøjagtige og unøjagtige rapporterede fødevarer og fødevaregrupper beregnet. Resultater Der var ingen signifikante forskelle i BMI mellem eleverne. Til gengæld viste studiet kønsforskelle i svaradfærd og svarnøjagtighed. Drengene rapporterede signifikant færre fødevarer (3.3) end pigerne (4.2) med OE-Q (p=0.005). Pigernes rapporterede deres indtag mere nøjagtigt end drengene alle metoder om end forskellen kun var signifikant for interviewmetoden. Begge køn rapporterede signifikant færre fødevarer med OE-Q sammenlignetmed den objektive reference (p&lt;0.001), mens PC-Q og interviewene ikke adskilte sig signifikantfra antallet af konsumerede fødevarer baseret på den objektive reference. 40% af børnene rapporterede én eller flere intrusioner (fantomfødevarer) i rapporteringer indsamlet med OE-Q og 77% med PC-Q. Beregning af intrusions rater fordelt på fødevaregrupper viste, at især fedtstof på brød og snacks var unøjagtige i rapporteringen af konsumeret madpakke. Af de identificerede intrusioner udgjorde 84% og 73% med henholdsvis OE-Q og PC-Q konfabulationer. Både omissioner og intrusioner var signifikant højere for den konsumerede skolemad sammenlignet med rapporteringen af madpakker på fødevaregruppeniveau. Der var ikke signifikant forskel på antallet af fødevaregrupper, der blev serveret, men elevernes faktiske indtag viste en signifikant om end lille forskel i fødevaregruppe diversitet. Det gennemsnitlige indtag af fødevaregrupper var 3.8 for madpakkerne og 3.5 for skolemad. Match raten for madpakker var 89% og 50% for skolemad med PC-Q. OE-Q registreringer for skolemaden var 67% og ikke signifikant forskellig fra madpakkerne. Intrusions raten var lavere for OE-Q rapporteringer sammenlignet med PC-Q og varierede mellem 10-20%. Forskningsmæssigt har studiet implikationer for den videre metode udvikling, såvel køn og metoder ser ud til at påvirke svarnøjagtigheden. Skriftlige åbne rapporteringer (OE-Q) er mindre udførligt forstået som antallet af fødevarer, der rapporteres. Den fundne forskel i svarnøjagtighed blandt drenge og piger bør undersøges i andre populationer med henblik på at bestemme om køn bidrager til en systematisk bias. Der ligger en stor metodisk udfordring i at måle fedtstof og snacks,der udgør et lille bidrag til frokosten på gruppeniveau, men som har betydning for kostkvaliteten på individ niveau. Endelig er der behov for at studere intrusioner og især konfabulationer for at bestemme i hvor høj grad de er udtryk for børnenes fantasi. Konklusion og perspektivering Der var forskelle mellem drenge og pigers svaradfærd og svarnøjagtighed, og betydningen af kønsforskelle bør tænkes ind i fremtidige studieraf indtag i skolen. Nøjagtigheden af de enkelte dataindsamlingsmetoder afhænger af frokostformatet og af de enkelte fødevarer og fødevarer grupper, der knytter sig til formatet. Selvrapporteret indtag af fødevaregrupper kan være egnet til at beskrive og evaluere forskellen i faktisk indtag mellem madpakker og skolemad. De anvendte og analyserammen kan med fordel anvendes til at vurdere andre måltider uden for skolen og blandt andre målgrupper. Der kan være et sundhedsfremmende potentiale i at formulere retningslinjer for indholdet i madpakker gennem en strukturel indsats.Background This thesis is embedded in the emerging scientific discipline of public health nutrition and explores the methodological aspect of measuring children’s ability to report their school lunch consumption accurately. Children’s dietary intake does not concurwith nutritional recommendations or food-based dietary guidelines which constitutes a public health concern for several reasons. In Denmark children’s food consumption during school hours constitutes more than a third of children’s daily energy intake. Assessment of school lunch consumption among children in their natural settings holds a range of methodological challenges when a population-based approach is applied. Children’s lunch on week-days is predominantly prepared by others and consequently children cannot be expected to provide detailed self-reported information beyond the food level. Parents, care-givers and kitchen staff may have accurate knowledge of what children are servedbut children are often asked what they have consumed. When self-reported methods are applied the remaining research questions relate to how accurately children’s actual consumption is reported.The majority of existing food level validation studies among children has addressed accuracy in relation to school meals. However, in several countries including Denmark packed lunch is the prevalent lunch format and the lack of packed lunch reporting accuracy studies needs to be addressed to increase the knowledge about school hour reporting accuracy in general. Objectives The aim of the present thesis was to assess food level reporting accuracy in Danish 11-year-old children’s self-reported school lunch consumption, and the aim was operationalized in following objectives. 1- To identify food items clustering by lunch format (Preliminary analyses) 2- To assess reporting accuracy in relation to gender and self-reported methods (Paper I) 3- To address aspects of reporting inaccuracy from intrusions by food group, against different objective measures, and classification of intrusions in stretches and confabulations (Paper II) 4- To assess how reporting accuracy differ by the lunch format consumed (Paper III) Material and methods The study was conducted as a cross-sectional dietary reporting study. The population consisted of 11-year-old children from three public schools in Copenhagen. The study was conducted on two consecutive days and assessed reporting accuracy ofpacked lunch and school meals. Digital pre- and post-meal images constituted the objective reference against which accuracy of self-reported consumption was assessed. Self-reports were obtained by a non-quantitative food level Lunch Recall Questionnaire (LRQ) which consisted of an open-ended random ordered report (OE-Q) and a precoded food-group prompted report (PC-Q). Individualmulti-pass recall interviews were conducted and anthropometrics were measured objectively. Food items reported and obtained from the images were characterized according to pre-defined food groups. Self-reported food items were categorized as matches(food items reported and verified by the images), omissions(food items not reported butverified by the images) and intrusions(food items reported but not verified by the images). Intrusions were further categorized as stretcheswhich expressed food items served on the plate, not consumed as determined by the images but reported consumed by the child and confabulations which expressed food items that were neither served nor consumed according to the images but reported consumed. Accuracy were expressed as match rates (% correctly reported food items), omission rates (% food items omitted), and intrusions rates (% phantom food items reported). Two sample t-tests were conducted to assess differences in background variables gender and BMI and differences in mean accuracy and inaccuracy rates were tested with paired t-test statistics. In the assessment of which objective measure reflected self-reports better a one-sided match t-test was applied. Results No significant difference was found in anthropometric characteristics by gender. Girls consumeda more varied packed lunch i.e. girls consumed a higher number of food items compared with boys. Further, girls reportedmore food items than boys with all self-reported methods although the difference in mean number reported was only significant in the open-ended part of the questionnaire (OE-Q) (p=0.005). Proportions of correctly reported food items consumed expressed as match rates ranged between 65 and 90%. Intrusion rates ranged between 12 and 36%. 40% of the children had at least one intrusion in self-reports obtained with OE-Q and the corresponding proportion was 77% with the PC-Q. Stratification by food groups showed that bread and fruits including nuts were most accurately reported. Intrusions and particularly omissions from fat spreads were high in OE-Q self-reports. Intrusions from snacks were substantial with the PC-Q reports. The majority of intrusions were confabulations (84% in OE-Q and 73% in PC-Q self-reports). Correspondingly stretches constituted 16% of the intrusions in OE-Q self-reports and 27% of the intrusions in PC-Qself-reports. Omission rates and intrusions rates were significantly higher for school meals compared with packed lunch consumption. Packed lunch consumption contributed to a higher diversity i.e. variation across food groups compared with school meal consumption. Conclusions and perspectives Accuracy among 11-year-old’ self-reported school lunch consumption differed by gender, self-reported method and lunch format. Gender differences were identified in relation to consumption, reporting and accuracy of self-reports. Accuracy of self-reported packed lunch obtained by interviews was higher compared with both the open-ended (OE-Q) and the pre-coded (PC-Q) parts of the Lunch Recall Questionnaire. Food level reporting accuracy was higher for packed lunch compared with school meals, and actual consumption of packed lunch was more diverse than school meals even though diversity in food served did not differ significantly. In the context of the public health nutrition research population-based methods to measure dietary intake are crucial and the need for a high level of details may be less prominent compared with nutrition research. In order to ensure construct validity of moderated recalls or records selection of food items needs further investigation - and may differ depending on the objective and research outcome of the particular study. An emergent but still undefined research question regards of what constitutes an acceptable level of accuracy at the food level, in relation to portion sizeestimations and consequently at nutrient level

Online Research Database In Technology

Accuracy of 11-year-olds selfreported school lunch consumption

http://orbit.dtu.dk/ws/files/74160277/Nina_Lyng_Afhandling..PDF

Accuracy of 11-year-olds selfreported school lunch consumption

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Online Research Database In Technology