Built environment and the evolution of cardiometabolic risk factors: a systematic review and meta-analysis of...

Cardiometabolic risk (CMR) is a monotonic if not linear continuum where, over time, incremental rises in biological risk can herald large increases in absolute disease risk and thus incident cardiometabolic disease (CMD). The built environment (BE)-green/open space, walkability, and food environment-may influence biological risk. Assessing the biological plausibility and temporal direction of such associations by linking BE features to the progression of biological indicators of CMR is essential for stronger causal inference. This review summarised longitudinal studies assessing BE factors and continuously expressed biological indicators of CMR.

Six databases were searched for longitudinal studies examining associations between BE features and continuous CMR factors, including fasting plasma glucose (FPG), triglycerides, lipoproteins, total cholesterol, glycated haemoglobin (HbA1c), systolic blood pressure (SBP), and diastolic blood pressure (DBP). Four authors screened the titles and abstracts, assessed the full text for inclusion, extracted data, and conducted quality appraisals. Associations were synthesised qualitatively, and a weighted z-score meta-analysis, incorporating study quality and sample size scores, was used to estimate the strength of the pooled evidence.

Sixteen longitudinal studies met inclusion criteria, with four studies examining multiple BE features. Green/open space was the most frequently examined feature (n = 9), followed by walkability (n = 8), and food environments (n = 3). Pooled weighted z-score meta-analyses showed that greater availability of green/open space environment was associated with lesser increases over time in SBP (n = 4/5, weighted z = 3.43, p < 0.001) and DBP (n = 3/3, weighted z = 2.89, p < 0.01), but findings were inconsistent for triglycerides (n = 1/2), HDL-C (n = 1/2), and FPG (n = 0/2). There was strong evidence for an association between greater walkability and lesser increases over time in SBP (n = 3/5, weighted z = 2.95, p < 0.01) and HbA1c (n = 2/2), but associations with DBP and FPG were inconsistent. Healthful food sources were associated with lesser increases over time in blood pressure, FPG and HbA1c levels (n = 1/1 for each outcome).

This review provides evidence for the role of the built environment in shaping CMR over time, particularly blood pressure and HbA1c, dependent on BE feature. Greater availability of green/open space environment and healthful food environment were reliably associated with a lesser progression of CMR. Evidence for walkability was inconsistent.