The impact of the Green Carpet and Blue Care in the Maastricht approach to reduce socioeconomic health inequalities

Background: In 2017, the city of Maastricht has started with the stepwise implementation of the Green Carpet: a five kilometer long park avenue that will replace the space that was occupied by the A2 highway which crossed the four lowest socio-economic status (SES) neighborhoods of the city.
At the same time, Blue Care is implemented in the same low-SES area of the city. In Blue Care, the municipality, health insurers, citizens and local partners in care and public health joined forces in an integrated approach to improve quality of life of the most vulnerable inhabitants of the city. This leads to the unique situation where two major changes in the physical and social environment of low-SES communities come together in Maastricht, both in time and place.

Objective: We aim to evaluate the effectiveness and process of the implementation of the Green Carpet and Blue Care, which together are referred to as INDIGO, on reducing socioeconomic health inequalities.

Study design: The effect study is a natural experiment with four parallel, independent groups, which are defined based on their geographical location. Group 1 consists of inhabitants of Heerlen, who are not exposed to Blue Care or the Green Carpet. Group 2 consists of inhabitants of neighborhoods in West Maastricht, that do not border the Green Carpet. Group 3 consists of inhabitants of neighborhoods in East Maastricht, that border the Green Carpet, but are not included in the Blue Care trial. The last group consists of inhabitants of four neighborhoods in East Maastricht that border the Green Carpet and included in the Blue Care trial. The process evaluation study will apply a qualitative research design using participatory observations, semi-structured interviews and document analyses.

Study population: For the effect evaluation, we include adult inhabitants of Maastricht and Heerlen, able to walking without walking aids and able to fill out a questionnaire in Dutch (with or without help from others). For the process evaluation, we will involve various stakeholders, such as policymakers of the municipality (planning domain, social domain), municipality health services, inhabitants, researchers and other parties.

Outcome measures: The main outcome measure is self-reported health-related quality of life, measured using the EQ-5D-3L. Secondary outcome measurements are context-specific physical activity behavior, sedentary behavior, and active transportation, which are measured using device-based measurements, i.e. GPS-logger and accelerometer. Process data will be collected throughout the study.

We hypothesize a synergetic, non-linear effect in people who are exposed to a more supportive physical and social environment, and we expect more than separate main effects on the outcomes of only supportive physical or social environments.

A baseline measurement on health-related quality of life, physical activity, sedentary behavior and active transportation is performed before the Green Carpet was opened, between September 2016 and July 2017. The first follow-up measurements took place one year after the opening of the Green Carpet, between September 2018 and July 2019. A second follow-up will take place between September 2020 and July 2021. Process evaluations will be conducted between April 2018 and April 2022.

This is a natural experiment evaluating the effects of two major events in the physical and social environment, which are not initiated or controlled by the research team. The event in the physical environment is the tunneling of a highway that crossed the city of Maastricht. On top of this tunnel, two one-way streets accommodate the remaining local traffic. The middle part of the profile, prioritized for pedestrians, cyclists and recreation, is separated from the adjacent streets by grass and trees, creating the so-called ‘Green Carpet’.

In the social environment, Blue Care was implemented. Blue Care is an integrated community approach, based on Berwicks triple aim approach, targeting an improvement in perceived patients’ health status, experience quality of life and healthcare costs. In addition, in the subjected neighbourhoods, several bottom-up, community-based social initiatives are being designed and implemented.