ArticleInternational journal of epidemiology2025
Confounding mechanisms and adjustment strategies in air pollution epidemiology: a case study assessment with the UK Biobank cohort.
Article in International journal of epidemiology, 2025. The graph could read no effect estimate from its abstract, so it casts no vote on the map. Cited by 3 papers, 1 of them a synthesis that pooled it.
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Who cites it
3 citing papers in PubMed, 1 synthesis or guideline pooled it.
- Outdoor air pollutants and asthma risk in adolescents: evidence from a systematic review and meta-analysis.Frontiers in public health · 2025Pooled it
- The choroid plexus, cognitive decline, and incident dementia: insights from the UK Biobank.Molecular psychiatry · 2026Article
- Sharing common measures of the environment across continents: challenges and opportunities for global studies of aging.The journals of gerontology. Series B, Psychological sciences and social sciences · 2026Article
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Abstract
backgroundCohort studies are instrumental in examining long-term risks associated with environmental exposures but require appropriate control for various confounding effects. In this contribution, we assessed this issue by investigating the relationship between fine particulate matter (PM2.5) exposure and mortality in a UK-based cohort.
methodsWe analysed data from half a million adults in the UK Biobank linked with time-varying individual-level exposure data and followed up during the period 2006-21. The assessment focused on confounding related to spatial and temporal patterns as well as due to measurable variables, including both contextual and individual-level factors. We performed an evaluation consisting of descriptive analyses, specification and interpretation of direct acyclic graphs (DAGs), and comparison of results from survival models.
resultsWe found correlations between PM2.5 exposure and mortality rates across time, geographical areas, and categories of measurable variables. The DAG indicated complex causal pathways and the need to adjust for a wide set of potential confounders. The regression analysis confirmed these patterns: the fully adjusted model estimated a hazard ratio (HR) of 1.25 (95% CI: 1.06-1.49) per 10 μg/m3 increments in PM2.5, but the association reversed to 0.82 (0.76-0.87) when excluding control for recruitment centre, suggesting strong spatial confounding. Calendar time showed stronger confounding effects compared to age. Area-level socio-economic indicators were more important than individual-level counterparts, while lack of control for lifestyle factors led to a noticeable overestimation.
conclusionsThis case-study illustration elucidates various confounding mechanisms in cohort studies on environmental risks and offers a critical evaluation of alternative adjustment strategies.
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