The environment an adult resides within is associated with their health behaviours, and their mental and physical health outcomes: a nationwide geospatial study

The neighourhood obesogenic built environment characteristics (OBCT) index: Practice versus theory

BACKGROUND

Obesity is a key risk factor for major chronic diseases such as type 2 diabetes and cardiovascular diseases. To extensively characterise the obesogenic built environment, we recently developed a novel Obesogenic Built environment CharacterisTics (OBCT) index, consisting of 17 components that capture both food and physical activity (PA) environments.

OBJECTIVES

We aimed to assess the association between the OBCT index and body mass index (BMI) in a nationwide health monitor. Furthermore, we explored possible ways to improve the index using unsupervised and supervised methods.

METHODS

The OBCT index was constructed for 12,821 Dutch administrative neighbourhoods and linked to residential addresses of eligible adult participants in the 2016 Public Health Monitor. We split the data randomly into a training (two-thirds; n = 255,187) and a testing subset (one-third; n = 127,428). In the training set, we used non-parametric restricted cubic regression spline to assess index's association with BMI, adjusted for individual demographic characteristics. Effect modification by age, sex, socioeconomic status (SES) and urbanicity was examined. As improvement, we (1) adjusted the food environment for address density, (2) added housing price to the index and (3) adopted three weighting strategies, two methods were supervised by BMI (variable selection and random forest) in the training set. We compared these methods in the testing set by examining their model fit with BMI as outcome.

RESULTS

The OBCT index had a significant non-linear association with BMI in a fully-adjusted model (p<0.05), which was modified by age, sex, SES and urbanicity. However, variance in BMI explained by the index was low (<0.05%). Supervised methods increased this explained variance more than non-supervised methods, though overall improvements were limited as highest explained variance remained <0.5%.

DISCUSSION

The index, despite its potential to highlight disparity in obesogenic environments, had limited association with BMI. Complex improvements are not necessarily beneficial, and the components should be re-operationalised.

Investigating the spatial and temporal variation of vape retailer provision in New Zealand: A cross-sectional and nationwide study

Smoking rates have decreased in Aotearoa New Zealand in recent years however, vaping has shown a dramatic upward trend especially among young people; up to 10% of young New Zealanders are now regular vapers. Importantly, the long-term health consequences for their future life are largely unknown. The accessibility of vape retailers is important, particularly in relation to the youths' daily activities and places such as schools where they spend a considerable amount of time and socialise. Despite this, we know little about the spatial patterning of vape retailers and even less of their socio-spatial patterning around schools. This ecological study utilised data from the New Zealand Specialist Vape Retailers register on nationwide vape retailer locations and combined them with whole-population sociodemographic characteristics and primary and secondary school data. We identified the prevalence of vape retailers and their spatial distribution by area-level deprivation, ethnicity and urban-rural classification by using descriptive statistics and (spatial) statistical modelling on the area-, school- and individual students-level (using disaggregated data on students). We found that almost 97% of all vape retailers are located within 1,600m (∼20-min walk) and 29% within 400m (∼5-min walk) of schools. Our research also identified increasing inequities by deprivation and ethnicity both for the overall population and particularly for students in the most deprived areas who experience a disproportionate presence and increase of new vape store retailers that disadvantage schools and students in these areas. This difference was particularly prominent for Pasifika populations in major urban environments.