Definition of the key points (PCC)

Objective

This scoping review explores the literature that studies the links between life-course socioeconomic status and weight status and characterize the life-course approach used. It will look at the state of knowledge in the scientific literature of the relationships between life-course socioeconomic indicators or longitudinal built environment indicators and weight status. The underlying hypothesis is that longitudinal exposure to a deprived socioeconomic or built environment is associated with the odds of living with overweight or with obesity. To achieve these objectives, we define inclusion and exclusion criteria (table 2) and a non-exhaustive list of concepts and keywords (table 3). Table 4 gives the results of the search strategy used in Medline (PubMed) and GeoBase (Embase).

1. Characterise the array of evidentiary sources within public health and social epidemiology domains.

2. Scrutinize the methodologies used to characterize life-course socioeconomic status.

3. Discern salient attributes or variables associated with a conceptual framework.

4. Identify and scrutinize lacunae in existing knowledge in life-course socioeconomic status studies.

Inclusion/exclusion criteria.

Keywords to formulate database search strategy.

Selection of studies and PRISMA diagram

The inclusion and exclusion criteria guide the study selection process. Based on these criteria, the above descriptors with Boolean operators allow us to formulate search strategies in Medline (PubMed), Web of Science and GeoBase (Embase) databases. The choice of these databases is justified because our topic is population health, which involves social, economic, environmental, medical and demographic issues. Each of these databases has particularities requiring a specific and adapted search strategy. We will identify a few benchmark articles in our preliminary readings. These articles correspond perfectly to our inclusion and exclusion criteria; they are the standard articles we seek. These benchmark articles allow us to know if our different search strategies in the databases are well formulated to capture the essence of the scientific literature. Thus, each search strategy should contain all or part of the selected benchmark articles.

Screening

The results obtained in the databases are exported in the Covidence software. After merging the results from the different databases, duplicates will be identified and deleted. Two independent reviewers evaluated the database of studies and thus obtained an invitation from Covidence to join the working group.

A first evaluation is based on the title, constituting an intermediate step. After that, the reviewers will decide which studies are retained for abstract reading. Each reviewer selects a list of studies for reading the full text from this second group. The reviewers then agree on the list of studies to be read in full.

Eligibility

The list of studies retained for our scoping review is thus obtained by consensus among the reviewers. Each reviewer’s choice is objectively justified, considering the previously established objectives and inclusion criteria. The PRISMA diagram (figure 1) below illustrates this systematic approach to selecting and retaining studies. In a conflict, a third reviewer will act as a judge.

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Figure 1

Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) flowchart (2020).

Data extraction and presentation of results

Data extraction is performed using the Covidence software. This step is made possible following the reviewers' study selection process. Thus, the following information is collected in the data extraction tab in Covidence.

Identification and study population

The identification section allows us to situate the study in geographical and temporal contexts and contributes to a better understanding of the different studies.

We will extract information on the study’s authors, the year of publication, the origin of the data used and the study populations. Authors' choice is justified trivially for copyright, recognition and identifying the article’s authors. The date of publication is important because it allows the study to be situated in a time frame and contributes to a better interpretation of the results of the study; the origin of the data, the location of the participants or the country of the participants helps to place the study in a political, geographic, social, economic, environmental and historical context. All these contextual elements are essential in understanding and interpreting the results. Socioeconomic and built environments are often specific to political, socioeconomic and historical contexts. Differences in wealth, inequality or services between and within countries require some caution when reconciling or comparing studies from different countries or contexts.

Objectives and methodologies

Identifying the objectives of the included studies is of importance for our scoping review. Indeed, this will allow us to classify the studies according to their type of environmental trajectories.

In terms of methodological aspects, the first step is to identify the statistical approach used to create the trajectories; we have indicated in our inclusion criteria that the studies must identify longitudinal socioeconomic or built environment indicators, so we wish to establish an exhaustive list of approaches, in addition to latent class analysis and sequence analysis, which are the most used methods in the scientific literature. The second step of the methodological aspects consists of determining the statistical method(s) used to calculate the associations between the trajectories thus created and the weight indicators in the case.

Results and highlights

The main results sought are measures of association between life-course socioeconomic or built environment longitudinal indicators and weight indicators.