Global burden of 288 causes of death and life expectancy decomposition in 204 countries and territories and 811 subnational locations, 1990–2021: a systematic analysis for the Global Burden of Disease Study 2021

BACKGROUND Regular, detailed reporting on population health by underlying cause of death is fundamental for public health decision making. Cause-specific estimates of mortality and the subsequent effects on life expectancy worldwide are valuable metrics to gauge progress in reducing mortality rates. These estimates are particularly important following large-scale mortality spikes, such as the COVID-19 pandemic. When systematically analysed, mortality rates and life expectancy allow comparisons of the consequences of causes of death globally and over time, providing a nuanced understanding of the effect of these causes on global populations. METHODS The Global Burden of Diseases, Injuries, and Risk Factors Study (GBD) 2021 cause-of-death analysis estimated mortality and years of life lost (YLLs) from 288 causes of death by age-sex-location-year in 204 countries and territories and 811 subnational locations for each year from 1990 until 2021. The analysis used 56 604 data sources, including data from vital registration and verbal autopsy as well as surveys, censuses, surveillance systems, and cancer registries, among others. As with previous GBD rounds, cause-specific death rates for most causes were estimated using the Cause of Death Ensemble model-a modelling tool developed for GBD to assess the out-of-sample predictive validity of different statistical models and covariate permutations and combine those results to produce cause-specific mortality estimates-with alternative strategies adapted to model causes with insufficient data, substantial changes in reporting over the study period, or unusual epidemiology. YLLs were computed as the product of the number of deaths for each cause-age-sex-location-year and the standard life expectancy at each age. As part of the modelling process, uncertainty intervals (UIs) were generated using the 2·5th and 97·5th percentiles from a 1000-draw distribution for each metric. We decomposed life expectancy by cause of death, location, and year to show cause-specific effects on life expectancy from 1990 to 2021. We also used the coefficient of variation and the fraction of population affected by 90% of deaths to highlight concentrations of mortality. Findings are reported in counts and age-standardised rates. Methodological improvements for cause-of-death estimates in GBD 2021 include the expansion of under-5-years age group to include four new age groups, enhanced methods to account for stochastic variation of sparse data, and the inclusion of COVID-19 and other pandemic-related mortality-which includes excess mortality associated with the pandemic, excluding COVID-19, lower respiratory infections, measles, malaria, and pertussis. For this analysis, 199 new country-years of vital registration cause-of-death data, 5 country-years of surveillance data, 21 country-years of verbal autopsy data, and 94 country-years of other data types were added to those used in previous GBD rounds. FINDINGS The leading causes of age-standardised deaths globally were the same in 2019 as they were in 1990; in descending order, these were, ischaemic heart disease, stroke, chronic obstructive pulmonary disease, and lower respiratory infections. In 2021, however, COVID-19 replaced stroke as the second-leading age-standardised cause of death, with 94·0 deaths (95% UI 89·2-100·0) per 100 000 population. The COVID-19 pandemic shifted the rankings of the leading five causes, lowering stroke to the third-leading and chronic obstructive pulmonary disease to the fourth-leading position. In 2021, the highest age-standardised death rates from COVID-19 occurred in sub-Saharan Africa (271·0 deaths [250·1-290·7] per 100 000 population) and Latin America and the Caribbean (195·4 deaths [182·1-211·4] per 100 000 population). The lowest age-standardised death rates from COVID-19 were in the high-income super-region (48·1 deaths [47·4-48·8] per 100 000 population) and southeast Asia, east Asia, and Oceania (23·2 deaths [16·3-37·2] per 100 000 population). Globally, life expectancy steadily improved between 1990 and 2019 for 18 of the 22 investigated causes. Decomposition of global and regional life expectancy showed the positive effect that reductions in deaths from enteric infections, lower respiratory infections, stroke, and neonatal deaths, among others have contributed to improved survival over the study period. However, a net reduction of 1·6 years occurred in global life expectancy between 2019 and 2021, primarily due to increased death rates from COVID-19 and other pandemic-related mortality. Life expectancy was highly variable between super-regions over the study period, with southeast Asia, east Asia, and Oceania gaining 8·3 years (6·7-9·9) overall, while having the smallest reduction in life expectancy due to COVID-19 (0·4 years). The largest reduction in life expectancy due to COVID-19 occurred in Latin America and the Caribbean (3·6 years). Additionally, 53 of the 288 causes of death were highly concentrated in locations with less than 50% of the global population as of 2021, and these causes of death became progressively more concentrated since 1990, when only 44 causes showed this pattern. The concentration phenomenon is discussed heuristically with respect to enteric and lower respiratory infections, malaria, HIV/AIDS, neonatal disorders, tuberculosis, and measles. INTERPRETATION Long-standing gains in life expectancy and reductions in many of the leading causes of death have been disrupted by the COVID-19 pandemic, the adverse effects of which were spread unevenly among populations. Despite the pandemic, there has been continued progress in combatting several notable causes of death, leading to improved global life expectancy over the study period. Each of the seven GBD super-regions showed an overall improvement from 1990 and 2021, obscuring the negative effect in the years of the pandemic. Additionally, our findings regarding regional variation in causes of death driving increases in life expectancy hold clear policy utility. Analyses of shifting mortality trends reveal that several causes, once widespread globally, are now increasingly concentrated geographically. These changes in mortality concentration, alongside further investigation of changing risks, interventions, and relevant policy, present an important opportunity to deepen our understanding of mortality-reduction strategies. Examining patterns in mortality concentration might reveal areas where successful public health interventions have been implemented. Translating these successes to locations where certain causes of death remain entrenched can inform policies that work to improve life expectancy for people everywhere. FUNDING Bill & Melinda Gates Foundation

Interactions interdécennales à millénaire du Climat, de l'Environnement et des populations Humaines en Afrique de l'Est au cours du dernier cycle climatique (CLEHA)

Projet ECLIPSE II 200523 page

Interactions interdécennales à millénaire du Climat, de l'Environnement et des populations Humaines en Afrique de l'Est au cours du dernier cycle climatique (CLEHA)

Projet ECLIPSE II 200523 page

Diatom-inferred salinity in palaeolakes: An indirect tracer of climate change

Gasse, Françoise; Barker, Philip; Gell, Peter A.; Fritz, Sherilyn C.; Chalie, François

RAINFALL SIGNAL IN MODERN POLLEN DATA FROM TOGO

International audienceno abstrac

Diatom-inferred salinity in palaeolakes: An indirect tracer of climate change

Lakes in arid and semi-arid regions respond to climatic change through shifts in lake water volume and ionic concentration. Because diatom distribution is highly correlated with lake hydrochemistry, diatoms can be used to infer changes in salinity and brine composition and thus to infer past climates. Here we critically examine the use of diatom-inferred salinity as a climate proxy, with examples taken from both modern waterbodies and sedimentary profiles. Sediment records may contain assemblages mixed from periods or sites of differing hydrochemistries because of the high degree of spatial and temporal heterogeneity in saline systems. Dissolution and diagenesis in saline brines may further complicate interpretation of sedimentary assemblages. Furthermore threshold effects, salinity regulation via groundwater seepage, antecedent conditions, and other aspects of local hydrology may modify the relationship between salinity change and climatic forcing. These complexities necessitate critical examination of the ecology and taphonomy of sedimentary assemblages, as well as evaluation of potential non-linearities in the salinity/climate relationship through comparison of diatom-inferred salinity with other proxy records of hydrochemical change, historical documents where they exist. and with other regional lake systems

POLLEN-DERIVED RAINFALL AND TEMPERATURE ESTIMATES FROM LAKE TANGANYIKA AND THEIR IMPLICATION FOR LATE PLEISTOCENE WATER LEVELS (VOL 40, PG 343, 1993)

International audienceno abstrac

Hydrological modeling of tropical closed Lake Ihotry (SW Madagascar): Sensitivity analysis and implications for paleohydrological reconstructions over the past 4000 years

Lake Ihotry is a closed saline lake extending in the semi-arid southwestern part of the Madagascar Island. Monitoring of lake level and chemistry, rainfall and pan evaporation close to the lake was conducted over more than two years, recording large seasonal variations in both lake area and salinity. In addition, diatom and pollen data from a 4000 years-sediment core showed that hydrological fluctuations of much larger magnitude have occurred in the past. The instrumental record was used to establish the present-day lake water balance and to calibrate a lake level and chloride content model at a daily time step. Sensitivity experiments showed that the present-day lake is very sensitive to rainfall variations, both through direct rainfall on the lake surface and through the local shallow groundwater availability. In the sediment core, diatom data document a wet episode with freshwater conditions from ca. 3300 to 2550-2000 cal. yr, followed by a desiccation trend punctuated by large variations of diatom-inferred salinity between X2250 and 1350 cal. yr, and finally the onset towards modern conditions by 700-650 cal. yr. A digital elevation model enabled to quantitatively reconstruct the morphometric parameters of an open lake. These lake area-depth-volume relationships were used in the combined water and chloride balances model to investigate conditions of the freshwater lake, and to simulate short-term oscillations of diatom-inferred salinity and the lake evolution towards its present state. We conclude that whatever the rainfall and/or evaporation changes accounting for, the regional water table evolution was an important factor controlling the long-term lake evolution, through its successive connection/disconnection to the lake

Millennium-long summer temperature variations in the European Alps as reconstructed from tree rings

This paper presents a reconstruction of the summer temperatures over the Greater Alpine Region (44.05°-47.41° N, 6.43°-13° E) during the last millennium based on a network of 38 multi-centennial larch and stone pine chronologies. Tree ring series are standardized using an Adaptative Regional Growth Curve, which attempts to remove the age effect from the low frequency variations in the series. The proxies are calibrated using the June to August mean temperatures from the HISTALP high-elevation temperature time series spanning the 1818-2003. The method combines an analogue technique, which is able to extend the too short tree-ring series, an artificial neural network technique for an optimal non-linear calibration including a bootstrap technique for calculating error assessment on the reconstruction. About 50% of the temperature variance is reconstructed. Low-elevation instrumental data back to 1760 compared to their instrumental target data reveal divergence between (warmer) early instrumental measurements and (colder) proxy estimates. The proxy record indicates cool conditions, from the mid-11th century to the mid-12th century, related to the Oort solar minimum followed by a short Medieval Warm Period (1200-1420). The Little Ice Age (1420-1830) appears particularly cold between 1420 and 1820 with summers that are 0.8 °C cooler than the 1901-2000 period. The new record suggests that the persistency of the late 20th century warming trend is unprecedented. It also reveals significant similarities with other alpine reconstruction