The association of built and natural environment features with multimorbidity: a systematic review

Background

Evidence is limited on whether features of the built and natural environment are associated with multimorbidity (≥ 2 long-term conditions). Improved understanding of these could inform prevention strategies.

Methods

This systematic review and meta-analysis examined the evidence of built and natural environment associations with multimorbidity prevalence and incidence (PROSPERO CRD 42024621458). Four databases were searched from inception to October 2024. Eligible studies analysed a built or natural environment exposure, multimorbidity prevalence or incidence, and were conducted in community-dwelling adults. Reference screening, data extraction, and risk-of-bias (RoB) assessment were conducted independently. Vote counting was used to synthesise association directions and standardised air pollution estimates were summarised in forest plots, with pooled estimates calculated for exposure-outcome combinations reported in ≥ 3 studies.

Results

Twenty-two studies (78 associations) were included that analysed 31 built or natural environment exposures. Studies measured air pollution (12 studies/58 associations), features that support active travel (6 studies/8 associations), green space/park availability (5 studies/5 associations), food environment features (2 studies/2 associations), and ‘other features’ (5 studies/5 associations). Pooled estimates found that multimorbidity prevalence was associated with 10 µg/m3 increase in PM2.5 (OR 1.22, 95% CI 0.99, 1.51), but there was less support for the association of PM2.5 with multimorbidity incidence (HR 1.68, 95% CI 0.78, 3.62). Study heterogeneity was substantial and most associations were at high/very high RoB. Findings for built and natural environment features other than air pollution were mixed.

Conclusions

There was consistent evidence on the associations between air pollution and multimorbidity prevalence, but evidence on other built and natural environment exposures and multimorbidity incidence is lacking.

Key messages

• There is consistent evidence that air pollutants are associated with multimorbidity prevalence.

• There is a lack of evidence about the association of other built and natural environment exposures with multimorbidity.