Trends in educational inequalities in smoking-attributable mortality and their impact on changes in general mortality inequalities: evidence from England and Wales, Finland, and Italy (Turin).

Background: Socioeconomic mortality inequalities are persistent in Europe but have been changing over time. Smoking is a known contributor to inequality levels, but knowledge about its impact on time trends in inequalities is sparse.

Methods: We studied trends in educational inequalities in smoking-attributable mortality (SAM) and assessed their impact on general mortality inequality trends in England and Wales (E&W), Finland, and Italy (Turin) from 1972 to 2017. We used yearly individually linked all-cause and lung cancer mortality data by educational level and sex for individuals aged 30 and older. SAM was indirectly estimated using the Preston-Glei-Wilmoth method. We calculated the slope index of inequality (SII) and performed segmented regression on SIIs for all-cause, smoking and non-SAM to identify phases in inequality trends. The impact of SAM on all-cause mortality inequality trends was estimated by comparing changes in SII for all-cause with non-SAM.

Results: Inequalities in SAM generally declined among males and increased among females, except in Italy. Among males in E&W and Finland, SAM contributed 93% and 76% to declining absolute all-cause mortality inequalities, but this contribution varied over time. Among males in Italy, SAM drove the 1976-1992 increase in all-cause mortality inequalities. Among females in Finland, increasing inequalities in SAM hampered larger declines in mortality inequalities.

Conclusion: Our findings demonstrate that differing education-specific SAM trends by country and sex result in different inequality trends, and consequent contributions of SAM on educational mortality inequalities. The following decades of the smoking epidemic could increase educational mortality inequalities among Finnish and Italian women.