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Background Anemia is a common disease which affects around 40% of children and 30% of reproductive age women and can have major health consequences. The present study reports the global, regional and national burden of anemia and its underlying causes between 1990 and 2019, by age, sex and socio-demographic index (SDI). Methods Publicly available data on the point prevalence and years lived with disability (YLDs) were retrieved from the global burden of disease (GBD) 2019 study for 204 countries and territories between 1990 and 2019. The point prevalence, YLD counts and rates per 100,000 population were presented, along with their corresponding 95% uncertainty intervals. Results In 2019, the global age-standardized point prevalence and YLD rates for anemia were 23,176.2 (22,943.5–23,418.6) and 672.4 (447.2–981.5) per 100,000 population, respectively. Moreover, the global age-standardized point prevalence and YLD rate decreased by 13.4% (12.1–14.5%) and 18.8% (16.9–20.8%), respectively, over the period 1990–2019. The highest national point prevalences of anemia were found in Zambia [49327.1 (95% UI: 46,838.5–51,700.1)], Mali [46890.1 (95% UI: 44,301.1–49,389.8)], and Burkina Faso [46117.2 (95% UI: 43,640.7–48,319.2)]. In 2019, the global point prevalence of anemia was highest in the 15–19 and 95+ age groups in females and males, respectively. Also, the burden of anemia was lower in regions with higher socio-economic development. Globally, most of the prevalent cases were attributable to dietary iron deficiency, as well as hemoglobinopathies and hemolytic anemias. Conclusions Anemia remains a major health problem, especially among females in less developed countries. The implementation of preventive programs with a focus on improving access to iron supplements, early diagnosis and the treatment of hemoglobinopathies should be taken into consideration.

ObjectiveTo report the global, regional, and national burden of chronic obstructive pulmonary disease (COPD) and its attributable risk factors between 1990 and 2019, by age, sex, and sociodemographic index.DesignSystematic analysis.Data sourceGlobal Burden of Disease Study 2019.Main outcome measuresData on the prevalence, deaths, and disability adjusted life years (DALYs) of COPD, and its attributable risk factors, were retrieved from the Global Burden of Disease 2019 project for 204 countries and territories, between 1990 and 2019. The counts and rates per 100 000 population, along with 95% uncertainty intervals, were presented for each estimate.ResultsIn 2019, 212.3 million prevalent cases of COPD were reported globally, with COPD accounting for 3.3 million deaths and 74.4 million DALYs. The global age standardised point prevalence, death, and DALY rates for COPD were 2638.2 (95% uncertainty intervals 2492.2 to 2796.1), 42.5 (37.6 to 46.3), and 926.1 (848.8 to 997.7) per 100 000 population, which were 8.7%, 41.7%, and 39.8% lower than in 1990, respectively. In 2019, Denmark (4299.5), Myanmar (3963.7), and Belgium (3927.7) had the highest age standardised point prevalence of COPD. Egypt (62.0%), Georgia (54.9%), and Nicaragua (51.6%) showed the largest increases in age standardised point prevalence across the study period. In 2019, Nepal (182.5) and Japan (7.4) had the highest and lowest age standardised death rates per 100 000, respectively, and Nepal (3318.4) and Barbados (177.7) had the highest and lowest age standardised DALY rates per 100 000, respectively. In men, the global DALY rate of COPD increased up to age 85-89 years and then decreased with advancing age, whereas for women the rate increased up to the oldest age group (≥95 years). Regionally, an overall reversed V shaped association was found between sociodemographic index and the age standardised DALY rate of COPD. Factors contributing most to the DALYs rates for COPD were smoking (46.0%), pollution from ambient particulate matter (20.7%), and occupational exposure to particulate matter, gases, and fumes (15.6%).ConclusionsDespite the decreasing burden of COPD, this disease remains a major public health problem, especially in countries with a low sociodemographic index. Preventive programmes should focus on smoking cessation, improving air quality, and reducing occupational exposures to further reduce the burden of COPD.

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Objective To report the levels and trends of prevalence, deaths, and disability‐adjusted life years (DALYs) due to musculoskeletal disorders, categorized as low back pain, neck pain, osteoarthritis (OA), rheumatoid arthritis (RA), gout, and other musculoskeletal disorders, across 195 countries and territories from 1990 to 2017 according to age, sex, and Sociodemographic Index (SDI; a composite of sociodemographic factors). Methods Data were obtained from the Global Burden of Disease (GBD) Study 2017. The fatal and nonfatal burdens of musculoskeletal disorders were estimated using the Cause of Death Ensemble model and Bayesian meta‐regression tool, respectively. Estimates were provided for all musculoskeletal disorders and the corresponding 6 categories at global, regional, and national levels from 1990 to 2017. Counts and age‐standardized rates per 100,000 population along with 95% uncertainty intervals (95% UIs) were reported for prevalence, deaths, and DALYs. Results Globally, there were ~1.3 billion prevalent cases (95% UI 1.2 billion, 1.4 billion), 121.3 thousand deaths (95% UI 105.6 thousand, 126.2 thousand), and 138.7 million DALYs (95% UI 101.9 million, 182.6 million) due to musculoskeletal disorders in 2017. Age‐standardized prevalence, death, and DALY rates per 100,000 population were 16,276.2 (95% UI 15,495.5, 17,145.8), 1.6 (95% UI 1.4, 1.6), and 1,720 (95% UI 1,264.4, 2,259.2), respectively. Age‐standardized prevalence (−1.6% [95% UI −2.4, −0.8]) and DALY rates (−3.5% [95% UI −4.7, −2.3]) decreased slightly from 1990. The global point prevalence rate of musculoskeletal disorders in 2017 was higher in women than in men and increased with age up to the oldest age group. Globally, the proportion of prevalent cases according to category of musculoskeletal disorders in 2017 was greatest for low back pain (36.8%), followed by other musculoskeletal disorders (21.5%), OA (19.3%), neck pain (18.4%), gout (2.6%), and RA (1.3%). These proportions did not change appreciably compared with 1990. The burden due to musculoskeletal conditions was higher in developed countries. The countries with the highest age‐standardized prevalence rates of musculoskeletal disorders in 2017 were Switzerland (23,346.0 [95% UI 22,392.6, 24,329.8]), Chile (23,007.9 [95% UI 21,746.5, 24,165.8]), and Denmark (22,166.1 [95% UI 20,817.2, 23,542.1]). The greatest increases from 1990 were found in Chile (10.8% [95% UI 6.6, 15.4]), Benin (8.8% [95% UI 6.7, 11.1]), and El Salvador (8.5% [95% UI 5.5, 11.9]). Conclusion There is a large burden of musculoskeletal disorders globally, with some notable inter‐country variation. Some countries have twice the burden of other countries. Increasing population awareness regarding risk factors, consequences, and evidence‐informed treatment strategies for musculoskeletal disorders with a focus on the older female population in developed countries is needed, particularly for low back and neck pain and OA, which contribute a large burden among this cohort.

AimTo report the point prevalence, deaths and disability-adjusted-life-years (DALYs) due to type 2 diabetes and its attributable risk factors in 204 countries and territories during the period 1990-2019.MethodsWe used the data of the Global Burden of Disease (GBD) Study 2019 to report number and age-standardised rates per 100 000 population of type 2 diabetes. Estimates were reported with 95% uncertainty intervals (UIs).ResultsIn 2019, the global age-standardised point prevalence and death rates for type 2 diabetes were 5282.9 and 18.5 per 100 000, an increase of 49% and 10.8%, respectively, since 1990. Moreover, the global age-standardised DALY rate in 2019 was 801.5 per 100 000, an increase of 27.6% since 1990. In 2019, the global point prevalence of type 2 diabetes was slightly higher in males and increased with age up to the 75-79 age group, decreasing across the remaining age groups. American Samoa [19876.8] had the highest age-standardised point prevalence rates of type 2 diabetes in 2019. Generally, the burden of type 2 diabetes decreased with increasing SDI (Socio-demographic Index). Globally, high body mass index [51.9%], ambient particulate matter pollution [13.6%] and smoking [9.9%] had the three highest proportions of attributable DALYs.ConclusionLow and middle-income countries have the highest burden and greater investment in type 2 diabetes prevention is needed. In addition, accurate data on type 2 diabetes needs to be collected by the health systems of all countries to allow better monitoring and evaluation of population-level interventions.

Data from the Global Burden of Disease Study 2019 were used to report the burden of migraine in 204 countries and territories during the period 1990 to 2019, through a systematic analysis of point prevalence, annual incidence, and years lived with disability (YLD). In 2019, the global age-standardised point prevalence and annual incidence rate of migraine were 14,107.3 (95% Uncertainty Interval [UI] 12,270.3-16,239) and 1142.5 (95% UI 995.9-1289.4) per 100,000, an increase of 1.7% (95% UI 0.7%-2.8%) and 2.1% (95% UI 1.1%-2.8%) since 1990, respectively. Moreover, the global age-standardised YLD rate in 2019 was 525.5 (95% UI 78.8-1194), an increase of 1.5% (95% UI -4.4% to 3.3%) since 1990. The global point prevalence of migraine in 2019 was higher in females and increased by age up to the 40 to 44 age group, then decreased with increased age.

BackgroundEpidemiologic research is often devoted to etiologic investigation, and so techniques that may facilitate mechanistic inferences are attractive. Some of these techniques rely on rigid and/or unrealistic assumptions, making the biologic inferences tenuous. The methodology investigated here is effect decomposition: the contrast between effect measures estimated with and without adjustment for one or more variables hypothesized to lie on the pathway through which the exposure exerts its effect. This contrast is typically used to distinguish the exposure's indirect effect, through the specified intermediate variables, from its direct effect, transmitted via pathways that do not involve the specified intermediates.MethodsWe apply a causal framework based on latent potential response types to describe the limitations inherent in effect decomposition analysis. For simplicity, we assume three measured binary variables with monotonic effects and randomized exposure, and use difference contrasts as measures of causal effect. Previous authors showed that confounding between intermediate and the outcome threatens the validity of the decomposition strategy, even if exposure is randomized. We define exchangeability conditions for absence of confounding of causal effects of exposure and intermediate, and generate two example populations in which the no-confounding conditions are satisfied. In one population we impose an additional prohibition against unit-level interaction (synergism). We evaluate the performance of the decomposition strategy against true values of the causal effects, as defined by the proportions of latent potential response types in the two populations.ResultsWe demonstrate that even when there is no confounding, partition of the total effect into direct and indirect effects is not reliably valid. Decomposition is valid only with the additional restriction that the population contain no units in which exposure and intermediate interact to cause the outcome. This restriction implies homogeneity of causal effects across strata of the intermediate.ConclusionsReliable effect decomposition requires not only absence of confounding, but also absence of unit-level interaction and use of linear contrasts as measures of causal effect. Epidemiologists should be wary of etiologic inference based on adjusting for intermediates, especially when using ratio effect measures or when absence of interacting potential response types cannot be confidently asserted.