Educational and social inequalities and cause-specific mortality: a prospective study in two municipalities of Mexico City

BACKGROUND: Social inequalities in adult mortality have been reported across diverse populations, but there is no large-scale prospective evidence from Mexico. We aim to quantify social, including educational, inequalities in mortality among adults in Mexico City. METHODS: The Mexico City Prospective Study recruited 150 000 adults aged 35+ years from Mexico City between 1998 and 2004. Participants were followed-up until 1 January 2021 for cause-specific mortality. Cox regression analysis yielded rate ratios (RRs) for death at ages 35-74 associated with education and examined, in exploratory analyses, the mediating effects of lifestyle and related risk factors. FINDINGS: Among 143 478 participants aged 35-74, there was a strong inverse association of education with premature death. Compared with participants with tertiary education, after adjustment for age and sex, those with no education had about twice the mortality rate (RR 1.84 [95% CI 1.71-1.98]), equivalent to approximately 6 years lower life expectancy, with RR of 1.78 (1.67-1.90), 1.62 (1.53-1.72) and 1.34 (1.25-1.42) among participants with incomplete primary, complete primary and secondary education, respectively. Education was most strongly associated with death from renal disease and acute diabetic crises (RR 3.65 [95% CI 3.05-4.38] for none vs. tertiary education) and from infectious disease (2.67 [2.00-3.56]), but there was an apparent higher rate of death from all specific causes studied with lower education. Lifestyle factors (smoking, alcohol drinking, leisure time physical activity) and related physiological correlates (adiposity, diabetes, blood pressure) accounted for 84% of the association of education with premature mortality. INTERPRETATION: In this Mexican population there were marked educational inequalities in premature adult mortality, which appeared to largely be accounted for by lifestyle and related risk factors. Effective interventions to reduce these risk factors could reduce inequalities and have a major impact on premature mortality. FUNDING: Wellcome Trust, the Mexican Health Ministry, the National Council of Science and Technology for Mexico, Cancer Research UK, British Heart Foundation, and the UK Medical Research Council Population Health Research Unit