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STUDY QUESTION What is the global, regional and national burden of polycystic ovary syndrome (PCOS), by age and socio-demographic index (SDI), over the period 1990–2019? SUMMARY ANSWER In 2019, the global age-standardized point prevalence, incidence and years lived with disability (YLD) of PCOS were 30.4, 29.5 and 29.9 per 100 000 population, respectively. WHAT IS KNOWN ALREADY Data from the Global Burden of Disease (GBD) study 2017 showed that the global age-standardized PCOS incidence rate increased 1.45% over the period 1990–2017. STUDY DESIGN, SIZE, DURATION A systematic analysis of the PCOS prevalence, incidence and YLDs across 204 countries and territories was performed. PARTICIPANTS/MATERIALS, SETTING, METHODS Data on the point prevalence, annual incidence and YLDs due to PCOS were retrieved from the GBD study 2019 for 204 countries and territories from 1990 to 2019. The counts and age-standardized rates (per 100 000) are presented, along with their corresponding 95% uncertainty intervals (UIs). MAIN RESULTS AND THE ROLE OF CHANCE In 2019, the global age-standardized point prevalence and annual incidence rates for PCOS were 1677.8 (95% UI: 1166.0 to 2192.4) and 59.8 (95% UI: 41.7 to 78.9) per 100 000, which represents a 30.4% and 29.5% increase since 1990, respectively. Moreover, the global age-standardized YLD rate in 2019 was 14.7 (6.3–29.5), an increase of 29.9% since 1990. In 2019, Italy (7897.0), Japan (6298.7) and New Zealand (5419.1) had the highest estimated age-standardized point prevalences of PCOS. Globally, the number of prevalent cases and the point prevalence of PCOS peaked in the 25–29 years and 40–44 years age groups, respectively. Positive associations were found between the burden of PCOS and the SDI at the regional and national levels. LIMITATIONS, REASONS FOR CAUTION Variations in how PCOS was defined is a major limitation that prevents valid comparisons between different regions. WIDER IMPLICATIONS OF THE FINDINGS Globally, the burden of PCOS has increased at an alarming rate, making it a major public health concern. Increasing public awareness about this common condition, improving management options and increasing support to reduce factors which lead to further complications, need to be public health priorities. STUDY FUNDING/COMPETING INTEREST(S) The Bill and Melinda Gates Foundation, who were not involved in any way in the preparation of this manuscript, funded the GBD study. The Shahid Beheshti University of Medical Sciences, Tehran, Iran (Grant No. 28709) also supported the present report. The authors declare no competing interests. TRIAL REGISTRATION NUMBER N/A.

Background: Preterm birth (PTB) leads to short-term and long-term adverse effects on newborns. Exposure to fine particulate matter (PM2.5) was positively related to PTB. However, the global annual average PM2.5 was three times than the recommended value in 1998–2014. Socio-demographic index (SDI) is a new indicator that comprehensively reflects the overall development level of a country, partly because of “the epidemiological transition”. Among other countries with higher and similar SDI levels, policy makers have the opportunity to learn from their successful experiences and avoid their mistakes by identifying whether their burdens of disease are higher or lower than the expected. However, it is unclear about the trends of the burden of PM2.5-related preterm birth in different countries and different levels of SDI regions. Additionally, the relationship between the SDI and the burden in 1990–2019 is also unclear. Methods: This was a retrospective study based on the Global Burden of Disease Study 2019 (GBD2019) database from 1990 to 2019. The burden of PM2.5-related PTB was measured by the age-standardized mortality rate (ASMR), age-standardized disability-adjusted life years rate (ASDR), mortality rate, and the disability-adjusted life years (DALYs). The annual percentage changes (APCs) and the average annual percentage changes (AAPCs) were used to reflect the trends over the past 30 years, which were calculated using a joinpoint model. The relationships between the ASMR, ASDR, and SDI were calculated using a Gaussian process regression. Findings: In 2019, the entire burden of PM2.5-related PTB was relatively high, where the ASMR and the ASDR were 0.76 and 67.71, increasing by 7.04% and 7.12%, respectively. It mainly concentrated on early neonates, boys, and on low-middle SDI regions. The increase in the burden of PM2.5-related PTB in low and low-middle SDI regions is slightly higher than the decrease in other SDI regions. In 2019, the burden varied greatly among different levels of SDI regions where ASMRs varied from 0.13 in high SDI regions to 1.19 in low-middle regions. The relationship between the expected value of the burden of PM2.5-related PTB and SDI presented an inverted U-shape, and it reached the maximum when SDI is around 0.50. The burdens in four regions (South Asia, North Africa and the Middle East, western sub-Saharan Africa, and southern sub-Saharan Africa) were much higher than the mean value. Boys bore more burden that girls. The sex ratio (boys:girls) of the burden showed a dramatically increasing trend in low SDI regions and a decreasing trend in middle SDI regions and high-middle SDI regions. These differences reflect the huge inequality among regions, countries, ages, and sex in the burden of PM2.5-related PTB. Conclusion: The overall burden of PM2.5-related PTB in 2019 was relatively high, mainly concentrated on early neonates, boys, and on low-middle SDI regions. It showed an increasing trend in low-middle and low SDI regions. The association between the burden and the SDI presented an inverted U-shape. It is very necessary to promulgate policies to prevent and control air pollution in countries with large and increasing exposure to PM2.5 pollution because it does not need action at an individual level. Focusing on public educational interventions, public and professional policies, and improving accessibility of prenatal care are other feasible ways for low and low-middle SDI countries. Policy makers should also appropriately allocate medical resources to boys and early newborns.

STUDY QUESTION What is the current burden of polycystic ovary syndrome (PCOS) at the global, regional, and country-specific levels in 194 countries and territories according to age and socio-demographic index (SDI)? SUMMARY ANSWER Slight increases in age-standardized incidence of PCOS and associated disability-adjusted life-years (DALYs) were evidenced among women of reproductive age (15–49 years) from 2007 to 2017 at the global level, and in most regions and countries. WHAT IS KNOWN ALREADY No detailed quantitative estimates of the PCOS incidence and DALYs by age and SDI in these 194 countries and territories have been published previously. STUDY DESIGN, SIZE, DURATION An age- and SDI-stratified systematic analysis of the PCOS incidence and DALYs across 194 countries and territories has been performed. PARTICIPANTS/MATERIALS, SETTING, METHODS We used data from the Global Burden of Diseases, Injuries and Risk Factors Study (GBD) 2017 to estimate the total and age-standard PCOS incidence rates and DALYs rates among women of reproductive age in both 2007 and 2017, and the trends in these parameters from 2007 to 2017. MAIN RESULTS AND THE ROLE OF CHANCE Globally, women of reproductive age accounted for 1.55 million (95% uncertainty intervals (UIs): 1.19–2.08) incident cases of PCOS and 0.43 million (0.19–0.82) associated DALYs. The global age-standardized PCOS incidence rate among women of reproductive age increased to 82.44 (64.65–100.24) per 100 000 population in 2017, representing an increase of 1.45% (1.43–1.47%) from 2007 to 2017. The rate of age-standardized DALYs increased to 21.96 (12.78–31.15) per 100 000 population in 2017, representing an increase of 1.91% (1.89–1.93%) from 2007 to 2017. Over the study period, the greatest increase in the age-standardized PCOS incidence and DALYs rates were observed in the middle-SDI and high-middle SDI regions, respectively. At the GBD regional level, the highest age-standardized incidence and DALY rates in 2017 were observed in Andean Latin America, whereas the largest percentage increases in both rates from 2007 to 2017 were observed in Tropical Latin America. At the national level, Ecuador, Peru, Bolivia, Japan, and Bermuda had the highest age-standardized incidence rates and DALYs rates in both 2007 and 2017. The highest increases in both the age-standardized incidence rates and DALYs rates from 2007 to 2017 were observed in Ethiopia, Brazil, and China. LIMITATIONS, REASONS FOR CAUTION Although the GBD (2017) study aimed to gather all published and unpublished data, the limited availability of data in some regions might have led to the estimation of wide UIs. Additionally, the PCOS phenotype is complicated and the diagnostic criteria are constantly changing. Consequently, the incidence of PCOS might have been underestimated. WIDER IMPLICATIONS OF THE FINDINGS Knowledge about the differences in the PCOS burden across various locations will be valuable for the allocation of resources and formulation of effective preventive strategies. STUDY FUNDING/COMPETING INTEREST(S) The study was supported by grants from the Innovative Talent Support Plan of the Medical and Health Technology Project in Zhejiang Province (2021422878), Ningbo Science and Technology Project (202002N3152), Ningbo Health Branding Subject Fund (PPXK2018-02), Sanming Project of Medicine in Shen-zhen (SZSM201803080), and National Social Science Foundation (19AZD013). No potential conflicts of interest relevant to this article were reported. TRIAL REGISTRATION NUMBER N/A

Background Cardiovascular disease is the leading cause of death in China. The aim of this study was to evaluate the levels of cardiovascular health among Chinese adults and to understand the geographic pattern of cardiovascular health. Methods In 2015, a total of 74,726 respondents aged ≥ 20 years with no history of cardiovascular disease were randomly sampled from 298 counties/districts of 31 provinces in mainland China and were interviewed. Seven metrics, including smoking, body mass index, physical activity, diet, total cholesterol, blood pressure, and fasting glucose, were determined. Ideal cardiovascular health was defined as the simultaneous presence of all metrics at the ideal level. A score ranging from 0 to 14 was calculated as the sum of all seven metrics for each province. Scores for cardiovascular health behaviors (smoking, body mass index, physical activity and diet) and those for cardiovascular health factors (smoking, total cholesterol, blood pressure, and fasting glucose) were also calculated. Findings The mean age was 44.4 ± 15.9 years, and 49.3% were women. The age-sex-standardized prevalence of ideal cardiovascular health was universally poor, ranging from 0.02% [95% confidence interval (CI): 0%, 0.05%] in Tibet to 2.76% (95% CI: 0.45%, 5.07%) in Heilongjiang. Ideal diet (7.1%) was the least common factor of the seven metrics in each province and varied considerably across provinces. Other component metrics of ideal cardiovascular health were also spatially patterned. In all provinces, women had higher scores than men for cardiovascular health, health behaviors and health factors. Differences in cardiovascular health and health behavior scores between urban and rural areas were associated with levels of socio-economic development. Interpretation Strategies for addressing poor cardiovascular health require geographic targeting and localized consideration. Funding This research was supported by National Key R&D Program, the Shenzhen Strategic Emerging Industry Development Special Fund, and the Fund of "Sanming" Project of Medicine in Shenzhen.

ObjectivesDisparities in the global burden of breast cancer have been identified. We aimed to investigate recent patterns and trends in the breast cancer incidence and associated mortality. We also assessed breast cancer-related health inequalities according to socioeconomic development factors.DesignAn observational study based on the Global Burden of Diseases.MethodsEstimates of breast cancer incidence and mortality during 1990–2016 were obtained from the Global Health Data Exchange database. Subsequently, data obtained in 2016 were described using the age-standardised and age-specific incidence, mortality and mortality-to-incidence (MI) ratios according to sociodemographic index (SDI) levels. Trends were assessed by measuring the annual percent change using the joinpoint regression. The Gini coefficients and concentration indices were used to identify between-country inequalities.ResultsCountries with higher SDI levels had worse disease incidence burdens in 2016, whereas inequalities in the breast cancer incidence had decreased since 1990. Opposite trends were observed in the mortality rates of high and low SDI countries. Moreover, the decreasing concentration indices, some of which became negative, among women aged 15–49 and 50–69 years suggested an increase in the mortality burdens in undeveloped regions. Conversely, inequality related to the MI ratio increased. In 2016, the MI ratios exhibited distinct gradients from high to low SDI regions across all age groups.ConclusionsThe patterns and trends in breast cancer incidence and mortality closely correlated with the SDI levels. Our findings highlighted the primary prevention of breast cancer in high SDI countries with a high disease incidence and the development of cost-effective diagnostic and treatment interventions for low SDI countries with poor MI ratios as the two pressing needs in the next decades.

Chronic Kidney Disease (CKD) is a major risk factor for mortality and morbidity, as well as a growing public health problem. Several studies describe the epidemiology of CKD (i.e. prevalence, incidence) by examining short time intervals. Conversely, the trend of epidemiology over time has not been well investigated, although it may provide useful information on how to improve prevention measures and the allocation of economic resources. Our aim here is to describe the main aspects of the epidemiology of CKD by focusing on its temporal variation. The global incidence of CKD has increased by 89% in the last 27 years, primarily due to the improved socio-demographic index and life-expectancy. Prevalence has similarly increased by 87% over the same period. Mortality rate has however decreased over the last decades, both in the general and CKD populations, due to a reduction in cardiovascular and infectious disease mortality. It is important to emphasize that the upward trend of incidence and prevalence of CKD can be explained by the ageing of the population, as well as by the increase in the prevalence of comorbidities such as hypertension, diabetes and obesity. It seems hard to compare trends between Italy and other countries because of the different methods used to assess epidemiologic measures. The creation of specific CKD Registries in Italy appears therefore necessary to monitor the trend of CKD and its comorbidities over time.