Objectives: Traffic-related pollution is associated with cardiovascular disease in general, but previous studies suggested that low socioeconomic status (SES) groups might be more susceptible towards a negative impact. We examined whether the association between long-term exposure to high traffic and early signs of coronary artery disease is modified by SES.
Methods: Individual-level medical and social data from a population-based study were linked with census information on neighbourhood socioeconomic characteristics. Residential exposure to traffic was defined as proximity to major roads using a geographical information system. We studied associations between high traffic and coronary artery calcification (CAC) within strata of SES to examine effect modification. Data stem from an epidemiological study in Germany including 2264 women and 2037 men (45–75 years).
Results: High traffic and low SES were both associated with higher amounts of calcification (⩾75th age-specific percentile). More participants with low SES lived close to major roads while stratified analyses did not indicate higher susceptibility in low SES groups. Participants with low SES and simultaneous exposure to high traffic had highest levels of CAC. For example, the prevalence of high calcification was 23.9% in better-educated men with low traffic exposure but 37.7% in lower-educated men with high traffic exposure (women: 22.0% vs 28.1%).
Conclusions: High traffic exposure was associated with coronary calcification in all social groups, but as low SES individuals had higher calcification in general and were also more often exposed to traffic, existing inequalities could be further shaped by traffic exposure.
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Funding The study is also supported by the German Ministry of Education and Science. Assessment of psychosocial factors and neighbourhood-level information is funded by the German Research Council (DFG; Project SI 236/8-1 and SI 236/9-1). Analyses combining environmental and social factors are additionally funded by the Volkswagen Stiftung. An additional research grant was received from Imatron, South San Francisco, California, which produced the EBCT scanners, and GE-Imatron, South San Francisco, California, after the acquisition of Imatron.
Competing interests None.
Ethics approval The study was approved by the Institutional Review Committee (Essen) and the German Council for Radiation Safety.
Advisory Board: T Meinertz, Hamburg (Chair); M Blettner, Mainz; C Bode, Freiburg; PJ de Feyter, Rotterdam, Niederlande; B Güntert, Hall i.T., Schweiz; F Gutzwiller, Schweiz; H Heinen, Bonn; O Hess, Bern, Schweiz; B Klein, Essen; H Löwel, Neuherberg; M Reiser, München; G Schmidt, Essen; M Schwaiger, München; C Steinmüller, Bonn; T Theorell, Stockholm, Schweden; SN Willich, Berlin.
Provenance and peer review Not commissioned; externally peer reviewed.
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