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Finding new answers in old trials with data linkage. A novel method to assess whether nutrient intake in infancy affects long-term cognition

Verfürden, Maximiliane Lara; (2021) Finding new answers in old trials with data linkage. A novel method to assess whether nutrient intake in infancy affects long-term cognition. Doctoral thesis (Ph.D), UCL (University College London). Green open access

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Abstract

Background Due to high attrition in randomised controlled trials (RCTs), cognitive effects of infant formula modifications remain uncertain. The aim of this thesis was to test a new method to minimise attrition and, through doing so, to compare differences in academic performance between children previously randomised to either nutritionally modified or standard infant formula. Methods Nine dormant infant formula RCTs conducted in England (1982-2001) were available for linkage to the National Pupil Database. Linkage was based on legal exemption from the need for participant consent. A trusted third party provided de-identified data for up to four candidate pupil matches per participant and agreement-metrics for all shared linkage variables. I completed the linkage of de-identified data, using auxiliary RCT variables and probabilistic methods. Six RCTs (n=1,563) were eligible for analysis, and a further three RCTs were used to assess linkage success and improve multiple imputation of missing data. Participant academic performance was measured using exam grades, with the primary outcome being General Certificate of Secondary Education (GCSE) Maths grades at age 16 years. Modified formula and standard formula groups were compared on an intention-to-treat basis, stratified by trial. Results Within the six trials eligible for analysis, primary outcome data was available for 86% of all participants. Available outcome data was substantially higher than the average of 22% above age 2 years in previous consent-based cognitive follow-ups of the trials. There was no evidence of benefit for GCSE Maths performance for any type of modified formula. Secondary academic outcomes provided weak evidence of harm for one of the formula modifications. Conclusions Unconsented linkage of dormant trials to administrative education data is feasible and leads to higher follow-up rates compared to traditional consented follow-up methods. None of the investigated nutritionally modified formula interventions improved academic performance.

Type: Thesis (Doctoral)
Qualification: Ph.D
Title: Finding new answers in old trials with data linkage. A novel method to assess whether nutrient intake in infancy affects long-term cognition
Event: UCL
Open access status: An open access version is available from UCL Discovery
Language: English
Additional information: Copyright © The Author 2021. Original content in this thesis is licensed under the terms of the Creative Commons Attribution-NonCommercial-NoDerivatives 4.0 International (CC BY-NC-ND 4.0) Licence (https://creativecommons.org/licenses/by-nc-nd/4.0/). Any third-party copyright material present remains the property of its respective owner(s) and is licensed under its existing terms. Access may initially be restricted at the author’s request.
UCL classification: UCL
UCL > Provost and Vice Provost Offices
UCL > Provost and Vice Provost Offices > School of Life and Medical Sciences
UCL > Provost and Vice Provost Offices > School of Life and Medical Sciences > Faculty of Population Health Sciences
UCL > Provost and Vice Provost Offices > School of Life and Medical Sciences > Faculty of Population Health Sciences > UCL GOS Institute of Child Health
UCL > Provost and Vice Provost Offices > School of Life and Medical Sciences > Faculty of Population Health Sciences > UCL GOS Institute of Child Health > Population, Policy and Practice Dept
URI: https://discovery.ucl.ac.uk/id/eprint/10128325
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