Development of the Portuguese European Deprivation Index 2021 and its association with all-cause mortality across multiple spatial scales

Background Socioeconomic inequalities remain major determinants of population health, and small-area measures of deprivation constitute essential tools for monitoring and addressing these inequalities. In this study, we developed the updated 2021 Portuguese version of the European Deprivation Index (EDI-PT 2021), described its spatial distribution, and evaluated its association with all-cause mortality. Results Using data from the 2021 European Union Statistics on Income and Living Conditions (EU-SILC) survey, we constructed an indicator of individual deprivation based on fundamental needs associated with both objective and subjective poverty. Variables common to both EU-SILC and the 2021 Portuguese census were identified and tested for association with individual deprivation to derive weights. The EDI-PT 2021 was calculated for 10,401 census block groups and subsequently aggregated to parish and municipality levels. The final index comprised nine weighted variables reflecting marital status, country of birth, education, employment, occupation, housing characteristics, household composition, and tenure status. Spatial distribution revealed marked territorial inequalities, with higher deprivation concentrated in southern and inland regions and lower deprivation along the northern and central coastal corridor. Associations with all-cause mortality, estimated using Bayesian spatial models, showed a clear dose–response relationship, with progressively higher mortality risks across deprivation quintiles. Compared with the least deprived areas, the most deprived exhibited a relative risk of 1.090 (95% Credible Interval: 1.067–1.115) at parish level and 1.103 (1.062–1.145) at municipality level. Conclusions The EDI-PT 2021 captures contemporary socioeconomic deprivation and shows significant associations with mortality across spatial scales, providing a robust tool for epidemiological research, surveillance, and evidence-based territorial planning.