Study on the Association Between the Introduction of Complementary Feeding and Infant Gut Microbiome Composition

Feasibility of complete questionnaire data collection

Percentage of questionnaires completed by recruited families (feasibility target: ≥ 80 %).

Feasibility of high-quality questionnaire data collection

Percentage of families for whom no contradictory or inconsistent information is identified across the three questionnaires (feasibility target: ≥ 80 %).

Feasibility of adherence to questionnaire timepoints

Percentage of answered questionnaires that comply with the predefined data collection timepoints between start of complementary feeding (CF) and T1, T2 and T3: T1 - CF: 0 - 8 days, CF - T2: 6 - 8 days, CF - T3: 13 - 15 days (feasibility target: ≥ 80 %).

Feasibility of adherence to stool sample collection timepoints

Percentage of collected stool samples that comply with the predefined data collection timepoints between start of complementary feeding (CF) and T1, T2 and T3: T1 - CF: 0 - 8 days, CF - T2: 6 - 8 days, CF - T3: 13 - 15 days (feasibility target: ≥ 80 %).

Feasibility of collecting analyzable stool samples

Percentage of collected stool samples for which 16S rRNA analysis was successfully completed (feasibility target: ≥ 90 %).

Feasibility of study participant recruitment

Recruitment rate will be described as number of recruited study participants per month. Reasons of withdrawal will be reported.

Feasibility of PPIE activities assessed by the project leader using the Public and Patient Engagement Evaluation Tool (PPEET) project questionnaire and by the PPIE participants using a modified Patient Engagement in Research Scale (PEIRS) tool.

The level of involvement achieved will be assessed by the project leader and PPIE participants using single-choice questions in the questionnaires. PPIE activities will be considered feasible if all PPIE activities can be conducted at the predefined level of involvement. Challenges and barriers encountered during the implementation of PPIE activities and their impact on the feasibility of PPIE activities will be assessed descriptively by the project leader and PPIE participants in the questionnaires.

Preliminary data on the association between complementary feeding and gut microbiome composition

Participant's health and dietary characteristics, as well as gut microbiome composition will be summarized at each timepoint using descriptive statistics. Where appropriate, plots will be used to visualize changes over time and patterns in gut microbiome composition. Gut microbiome composition will be described based on the relative abundance of the most common bacteria, microbial diversity within individual samples (α-diversity), and differences in overall microbial community composition between timepoints (β-diversity). Any statistical analyses investigating associations between the introduction of complementary feeding and gut microbiome composition will be considered explanatory and reported using confidence internals. These analyses will not include p-values or support confirmatory conclusions.