Abstract / Summary
Abstract Background: Whether Pacific Island life expectancy reflects a population's progress through the longevity transition or the period in which it occurred has not previously been distinguished. Existing evidence is fragmented, focusing on selected countries, age groups, diseases, or risks, or on broader analyses that omit most Pacific populations. Using a life-course framework and Global Burden of Disease (GBD) Study data spanning 1950–2023, we provide the first comparison of the epidemiological transition across all 18 Pacific Island countries and territories (PICTs), distinguishing position from timing effects. Methods: We used GBD 2023 estimates for 18 PICTs. We modelled annual life-expectancy change as a function of baseline life expectancy and calendar time, benchmarking Pacific trajectories against global patterns with and without Socio-demographic Index (SDI) adjustment, and against longevity-transition stage and period. We examined sex differentials and age- and cause-specific contributions to life-expectancy change across countries, subregions, and Oceania; derived mortality concentration ratios; compared leading causes and risks between 1990 and 2023; and partitioned potential lifespan into healthy, mortality-loss, and morbidity-loss components. Findings: Life expectancy in Oceania rose from 52·8 to 69·1 years (1950–2023), but improvement was 0·137 years per year slower than in global comparators after SDI adjustment (95% CI −0·205 to −0·070), with all 18 PICTs below the global benchmark and Nauru, the Solomon Islands, Tuvalu, and the Marshall Islands furthest below. Longevity transition stage (P=0·031) and historical period (P<0·001) were independently associated with the pace of gain, which fell more than sixfold across stages — from 0·417 to 0·064 years per year, the ages 25–69 contribution falling to zero — and turned negative during 2019–2022. The female survival advantage widened across stages (4·2 to 5·4 years), peaking by period in 1978–2000. Morbidity-related loss rose in all 18 PICTs at ages 25–69 and in 16 at ages 5–24 despite falling mortality-related loss; by 2023, healthy years fell from over 92% of potential lifespan at ages 0–24 to 76·0–76·9% at 25–69 and 36·6–41·1% at 70+. Causes and risks converged on ischaemic heart disease and cardiometabolic exposures, except in Papua New Guinea and the Solomon Islands, where particulate-matter pollution persisted. These patterns define four overlapping life-course transitions — early survival, youth health, premature cardiometabolic, and advanced ageing — coexisting within countries rather than following a fixed sequence. Interpretation: The Pacific epidemiological transition has been heterogeneous, asynchronous, and slower than in global comparators at comparable longevity and historical time-points — a shortfall shared regionally rather than confined to a few countries. Similar life expectancy masks differences in timing, sex differentials, age-specific mortality, morbidity, causes, and risks, which resolve into four overlapping life-course transitions advancing at different rates within the same country, with ages 25–69 now the binding constraint. The findings support differentiated, life-course-specific health priorities across Pacific Island countries and territories.