In French Guiana, life expectancy lags 2 to 3 years behind mainland France. Beyond widespread poverty, structural underdevelopment, and low physician density, the Guianese exposome differs radically from that of mainland France. Avoidable mortality — deaths that could have been prevented through prevention or care — had never been quantified in detail. This study aims to measure its extent, structure, and social cost over the 2001–2023 period.

This study analyses avoidable premature mortality below age 75 in French Guiana and mainland France over the period 2001–2023, using national cause-of-death statistics (CépiDc Inserm). The OECD/Eurostat 2022 list was applied to distinguish prevention-amenable from treatment-amenable causes. Standardized mortality rates (SMR) were calculated by direct standardization on the European Standard Population. Years of Life Lost (YLL) and Disability-Adjusted Life Years (DALY) were estimated using the Global Burden of Disease 2019 methodology. The fraction attributable to environment and poverty was quantified using WHO 2016 Population Attributable Fractions (PAF). The health-economic analysis used a harmonized value of a statistical life year (VSLY) of €135,000/yr for both territories.

The standardized avoidable mortality rate stood at 277.8 (95%CI: 268.0–287.9) per 100,000 inhabitants in French Guiana versus 198.1 (197.7–198.5) in mainland France (excess mortality +40% (35–45%)). The preventable component exceeded mainland France by 38% (184.8 (178.5–191.3) vs 134.2) and the treatable component by 46% (93.0 (85.7–100.6) vs 63.9). Infectious diseases showed the most pronounced excess (ratio × 4.2 (3.6–5.0)), followed by COVID-19 (× 3.4 (3.0–3.9)) and perinatal mortality (× 2.4 (2.0–2.6)). Over 23 years (2001–2023), standardized avoidable YLL increased by 43% in French Guiana, while declining 19% in France. Environment and poverty accounted for 47.5% (34.1–60.9%) of avoidable mortality in French Guiana versus 29.2% (20.9–37.5%) in mainland France. Using a harmonized national VSLY of €135,000, the standardized cost for French Guiana was €922k (761–1,082k) per 100,000 inhabitants per year versus €808k (686–930k) in France (ratio × 1.14 (1.10–1.18)); this cost represented 36.0% of Guianese GDP, more than double the relative burden observed in France (17.3%). Poverty was the most discriminating determinant, with a ratio of × 2.49 (1.7–3.7) on standardized costs and a weight of 6.9% of Guianese GDP versus 1.5% in France.

These results highlight the singularity of Guianese epidemiology and the major, growing burden of poverty and environmental factors on premature mortality.