Obesogenic environment and the prevalence of cardio-vascular disease risk factors in the Netherlands: A pooled analysis of 6 cohort studies

Cardio vascular diseases (CVD) are the leading cause of death worldwide, taking about 17.9 million lives yearly . The burden of CVD is not just a health issue, but also an economic challenge to healthcare systems. The World Heart Federation estimates that the total global cost of CVD will rise from roughly USD 863 billion in 2010 to USD 1044 billion in 2030 (2). In Europe and the Netherlands specifically, declines in the incidence of CVD during the last 27 years have been small, and despite sustained declines in CVD mortality, it remains one of the most frequent causes of death (3). Thus, it is important to find strategies that reduce CVD risk.
There are multiple established risk factors for CVD. These include dyslipidemia, hypertension and obesity (3). There is a continuous linear relationship between both blood pressure and LDL-cholesterol levels, and CVD outcomes (4, 5). Obesity can directly and indirectly affect CVD risk (6). Direct effects are mediated by obesity-induced structural and functional adaptations of the cardiovascular system. Indirect effects are mediated by other CVD risk factors. Rates of these risk factors are either still increasing or not decreasing fast enough to reach goals set by the World Health Organization and European Society of Cardiology (3).
The above-mentioned risk factors are mainly driven by obesogenic behaviors, such as diet, physical activity and sedentary behavior (7-11). These behavioral factors are individually associated with CVD risk factors, and also collectively relate to overweight/obesity, which is the result of an imbalance: too little ‘energy out’ (physical activity, sedentary behavior) and too much ‘energy in’ (diet) (12). Obesogenic behavioral change has mainly been the target of individual focused interventions. However, strategies focused on the obesogenic environment have the potential to improve population health on a broader scale.  
It is suggested that obesogenic behaviors are partially affected by environmental factors. For example, components of the food environment, such as variety and density of food outlets may be linked to diet outcomes (13-16). Furthermore, neighborhood accessibility for walking and cycling may be linked to increased overall physical activity and decreased sedentary behavior (17-21). In line with this, epidemiological literature suggests a link between components of the obesogenic environment, such as access to healthy food and physical activity recourses and CVD risk factors (22-28).
However, evidence for the relationship between obesogenic environmental factors and CVD risk factors remains inconclusive. This is largely due to substantial heterogeneity between studies, but this hypothesis has also mainly been studied in a traditional single exposure/single outcome analysis approach (29-31). Currently, a combined exposure approach is growingly being favored since individual exposures are not easily singled out, people are always exposed to multiple factors at the same time, and explanatory power from single exposures has been consistently low.
Moreover, unhealthy behaviors are often clustered and also potentially encouraged by the environment in which people live (32). That is why a combined exposure, conveyed in an index, may be a good representation of a specific living environment as a whole. This concept is already used for environmental aspects such as walkability, which combines multiple environmental features that facilitate walking (33). Therefore, we aim to investigate the combined effect of the obesogenic environment on hypertension, dyslipidemia and obesity in a multi-cohort study.
To assess attributes of the lifestyle environment in a combined exposure approach, we will use the Obesogenic Built-environmental CharacterisTics (OBCT) index, which is currently being developed within GECCO. The OBCT index incorporates environmental features -a set of single exposures as well as indices- that are associated with both energy intake (food intake) and energy expenditure (physical activity, active transport) behaviors. The components are found respectively from an umbrella review on the built environment and obesity, internal discussion and expert consultation (34).