Sex/gender in the association between ambient air pollution and cardiovascular mortality: Systematic review and...

When assessing the association between air pollution and cardiovascular mortality, it remains unclear whether females or males are more susceptible and whether and to what extent the pre-existing studies have accounted for different sex/gender dimensions. We searched three databases to identify short-term and long-term studies on the association between air pollution and cardiovascular mortality published 2000-2023 to assess their integration of sex/gender. We further evaluated whether sex/gender was a source of heterogeneity within these through a moderator analysis using random effects models. We examined sex/gender differences through random effects pooling of the female-to-male-ratio (FMR) of each study. We identified 106 studies, all of which operationalised sex/gender in binary terms and lacked a sex/gender-theoretical concept. However, the biological and social dimensions of sex/gender were indirectly included in the discussions. Meta-analyses did not identify sex/gender as a source of heterogeneity (e.g. short-term particulate matter with a diameter <10μm (PM₁₀): p-value of moderator test= 0.85; long-term: 0.34). The pooled FMR showed no sex/gender differences for short-term associations (1.0[CI: 0.0;0.0] for each air pollutant) and a trend towards higher effect estimates for males than females in long-term studies with a pooled FMR ranging from 0.93 to 0.99. Binary categorisation without conceptualisation does not appear to be sufficient to identify vulnerable sex/gender groups, if any, in the association between air pollution and cardiovascular mortality. Considering the multiple biological and sociocultural dimensions of sex/gender from the very beginning of study planning will help to move beyond speculative discussions and derive meaningful action for prevention and health care.