Temporal patterns of cancer burden in Asia, 1990-2019: a systematic examination for the Global Burden of Disease 2019 study

Background

Cancers represent a challenging public health threat in Asia. This study examines the temporal patterns of incidence, mortality, disability and risk factors of 29 cancers in Asia in the last three decades.

Methods

The age, sex and year-wise estimates of incidence, mortality, and disability-adjusted life years (DALYs) of 29 cancers for 49 Asian countries from 1990 through 2019 were generated as a part of the Global Burden of Disease, Injuries and Risk Factors 2019 study. Besides incidence, mortality and DALYs, we also examined the cancer burden measured in terms of DALYs and deaths attributable to risk factors, which had evidence of causation with different cancers. The development status of countries was measured using the socio-demographic index. Decomposition analysis was performed to gauge the change in cancer incidence between 1990 and 2019 due to population growth, aging and age-specific incidence rates.

Findings

All cancers combined claimed an estimated 5.6 million [95% uncertainty interval, 5.1-6.0 million] lives in Asia with 9.4 million [8.6-10.2 million] incident cases and 144.7 million [132.7-156.5 million] DALYs in 2019. The age-standardized incidence rate (ASIR) of all cancers combined in Asia was 197.6/100,000 [181.0-214.4] in 2019, varying from 99.2/100,000 [76.1-126.0] in Bangladesh to 330.5/100,000 [298.5-365.8] in Cyprus. The age-standardized mortality rate (ASMR) was 120.6/100,000 [110.1-130.7] in 2019, varying 4-folds across countries from 71.0/100,000 [59.9-83.5] in Kuwait to 284.2/100,000 [229.2-352.3] in Mongolia. The age-standardized DALYs rate was 2970.5/100,000 [2722.6-3206.5] in 2019, varying from 1578.0/100,000 [1341.2-1847.0] in Kuwait to 6574.4/100,000 [5141.7-8333.0] in Mongolia. Between 1990 and 2019, deaths due to 17 of the 29 cancers either doubled or more, and 20 of the 29 cancers underwent an increase of 150% or more in terms of new cases. Tracheal, bronchus, and lung cancer (both sexes), breast cancer (among females), colon and rectum cancer (both sexes), stomach cancer (both sexes) and prostate cancer (among males) were among top-5 cancers in most Asian countries in terms of ASIR and ASMR in 2019 and cancers of liver, stomach, hodgkin lymphoma and esophageal cancer posted the most significant decreases in age-standardized rates between 1990 and 2019. Among the modifiable risk factors, smoking, alcohol use, ambient particulate matter (PM) pollution and unsafe sex remained the dominant risk factors between 1990 and 2019. Cancer DALYs due to ambient PM pollution, high body mass index and fasting plasma glucose has increased most notably between 1990 and 2019.

Interpretation

With growing incidence, cancer has become more significant public health threat in Asia, demanding urgent policy attention and guidance. Its heightened risk calls for increased cancer awareness, preventive measures, affordable early-stage detection, and cost-effective therapeutics in Asia. The current study can serve as a useful resource for policymakers and researchers in Asia for devising interventions for cancer management and control.

Funding

The GBD study is funded by the Bill and Melinda Gates Foundation.

The burden of antimicrobial resistance in the Americas in 2019: a cross-country systematic analysis

Background

Antimicrobial resistance (AMR) is an urgent global health challenge and a critical threat to modern health care. Quantifying its burden in the WHO Region of the Americas has been elusive-despite the region's long history of resistance surveillance. This study provides comprehensive estimates of AMR burden in the Americas to assess this growing health threat.

Methods

We estimated deaths and disability-adjusted life-years (DALYs) attributable to and associated with AMR for 23 bacterial pathogens and 88 pathogen-drug combinations for countries in the WHO Region of the Americas in 2019. We obtained data from mortality registries, surveillance systems, hospital systems, systematic literature reviews, and other sources, and applied predictive statistical modelling to produce estimates of AMR burden for all countries in the Americas. Five broad components were the backbone of our approach: the number of deaths where infection had a role, the proportion of infectious deaths attributable to a given infectious syndrome, the proportion of infectious syndrome deaths attributable to a given pathogen, the percentage of pathogens resistant to an antibiotic class, and the excess risk of mortality (or duration of an infection) associated with this resistance. We then used these components to estimate the disease burden by applying two counterfactual scenarios: deaths attributable to AMR (compared to an alternative scenario where resistant infections are replaced with susceptible ones), and deaths associated with AMR (compared to an alternative scenario where resistant infections would not occur at all). We generated 95% uncertainty intervals (UIs) for final estimates as the 25th and 975th ordered values across 1000 posterior draws, and models were cross-validated for out-of-sample predictive validity.

Findings

We estimated 569,000 deaths (95% UI 406,000-771,000) associated with bacterial AMR and 141,000 deaths (99,900-196,000) attributable to bacterial AMR among the 35 countries in the WHO Region of the Americas in 2019. Lower respiratory and thorax infections, as a syndrome, were responsible for the largest fatal burden of AMR in the region, with 189,000 deaths (149,000-241,000) associated with resistance, followed by bloodstream infections (169,000 deaths [94,200-278,000]) and peritoneal/intra-abdominal infections (118,000 deaths [78,600-168,000]). The six leading pathogens (by order of number of deaths associated with resistance) were Staphylococcus aureus, Escherichia coli, Klebsiella pneumoniae, Streptococcus pneumoniae, Pseudomonas aeruginosa, and Acinetobacter baumannii. Together, these pathogens were responsible for 452,000 deaths (326,000-608,000) associated with AMR. Methicillin-resistant S. aureus predominated as the leading pathogen-drug combination in 34 countries for deaths attributable to AMR, while aminopenicillin-resistant E. coli was the leading pathogen-drug combination in 15 countries for deaths associated with AMR.

Interpretation

Given the burden across different countries, infectious syndromes, and pathogen-drug combinations, AMR represents a substantial health threat in the Americas. Countries with low access to antibiotics and basic health-care services often face the largest age-standardised mortality rates associated with and attributable to AMR in the region, implicating specific policy interventions. Evidence from this study can guide mitigation efforts that are tailored to the needs of each country in the region while informing decisions regarding funding and resource allocation. Multisectoral and joint cooperative efforts among countries will be a key to success in tackling AMR in the Americas.

Funding

Bill & Melinda Gates Foundation, Wellcome Trust, and Department of Health and Social Care using UK aid funding managed by the Fleming Fund.

The burden of stomach cancer mortality by county, race, and ethnicity in the USA, 2000-2019: a systematic analysis of health disparities

Background

There are persistent disparities in stomach cancer mortality among racial-ethnic groups in the USA, but the extent to which these patterns vary geographically is not well understood. This analysis estimated age-standardised mortality for five racial-ethnic groups, in 3110 USA counties over 20 years, to describe spatial-temporal variations in stomach cancer mortality and disparities between racial-ethnic groups.

Methods

Redistribution methods for insufficient cause of death codes and validated small area estimation methods were applied to death registration data from the US National Vital Statistics System and population data from the US National Center for Health Statistics to estimate annual stomach cancer mortality rates. Estimates were stratified by county and racial-ethnic group (non-Latino and non-Hispanic [NL] American Indian or Alaska Native [AIAN], NL Asian or Pacific Islander [Asian], NL Black [Black], Latino or Hispanic [Latino], and NL White [White]) from 2000 to 2019. Estimates were corrected for misreporting of racial-ethnic group on death certificates using published misclassification ratios. We masked (ie, did not display) estimates for county and racial-ethnic group combinations with a mean annual population of less than 1000; thus, we report estimates for 3079 (of 3110) counties for the total population, and 474, 667, 1488, 1478, and 3051 counties for the AIAN, Asian, Black, Latino, and White populations, respectively.

Findings

Between 2000 and 2019, national age-standardised stomach cancer mortality was lowest among the White population in every year. Nationally, stomach cancer mortality declined for all racial-ethnic groups across this time period, with the most rapid declines occurring among the Asian (percent decline 48.3% [45.1-51.1]) and Black populations (42.6% [40.2-44.6]). Mortality among the other racial-ethnic groups declined more moderately, decreasing by 36.7% (35.3-38.1), 35.1% (32.2-37.7), and 31.6% (23.9-38.0) among the White, Latino, and AIAN populations, respectively. Similar patterns were observed at the county level, although with wide geographic variation. In 2019, a majority of counties had higher mortality rates among minoritised racial-ethnic populations compared to the White population: 81.1% (377 of 465 counties with unmasked estimates for both racial-ethnic groups) among the AIAN population, 88.2% (1295 of 1469) among the Latino population, 99.4% (663 of 667) among the Asian population, and 99.9% (1484 of 1486) among the Black population. However, the size of these disparities ranged widely across counties, with the largest range from 0.3 to 17.1 among the AIAN population.

Interpretation

Stomach cancer mortality has decreased substantially across populations and geographies in the USA. However, disparities in stomach cancer mortality among racial-ethnic groups are widespread and have persisted over the last two decades. Local-level data are crucial to understanding the scope of this unequal burden among minoritised groups in the USA.

Funding

National Institute on Minority Health and Health Disparities; National Heart, Lung, and Blood Institute; National Cancer Institute; National Institute on Aging; National Institute of Arthritis and Musculoskeletal and Skin Diseases; Office of Disease Prevention; and Office of Behavioral and Social Sciences Research, National Institutes of Health (contract #75N94019C00016).

Time trends in tuberculosis mortality across the BRICS: an age-period-cohort analysis for the GBD 2019

BACKGROUND

Tuberculosis is the leading cause of death from a single infectious agent among the HIV-negative population and ranks first among the HIV-positive population. However, few studies have assessed tuberculosis trends in Brazil, Russia, India, China and South Africa (BRICS) or with an emphasis on HIV status. This study assesses the time trends of tuberculosis mortality across the BRICS with an emphasis on HIV status from 1990 to 2019.

METHODS

We obtained tuberculosis data from the Global Burden of Disease 2019 study (GBD 2019). We calculated the relative proportion of tuberculosis to all communicable, maternal, neonatal, and nutritional diseases by HIV status across the BRICS. We used age-period-cohort modelling to estimate cohort and period effects in tuberculosis from 1990 to 2019, and calculated net drift (overall annual percentage change), local drift (annual percentage change in each age group), longitudinal age curves (expected longitudinal age-specific rate), and period (cohort) relative risks.

FINDINGS

There were 549,522 tuberculosis deaths across the BRICS in 2019, accounting for 39.3% of global deaths. Among HIV-negative populations, the age-standardised mortality rate (ASMR) of tuberculosis in BRICS remained far higher than that of high-income Asia Pacific countries, especially in India (36.1 per 100 000 in 2019, 95% UI [30.7, 42.6]) and South Africa (40.1 per 100 000 in 2019, 95% UI [36.8, 43.7]). China had the fastest ASMR reduction across the BRICS, while India maintained the largest tuberculosis death numbers with an annual decrease much slower than China's (-4.1 vs -8.0%). Among HIV-positive populations, the ASMR in BRICS surged from 0.24 per 100 000 in 1990 to 5.63 per 100 000 in 2005, and then dropped quickly to 1.70 per 100 000 in 2019. Brazil was the first country to reverse the upward trend of HIV/AIDS-tuberculosis (HIV-TB) mortality in 1995, and achieved the most significant reduction (-3.32% per year). The HIV-TB mortality in South Africa has realised much progress since 2006, but still has the heaviest HIV-TB burden across the BRICS (ASMR: 70.0 per 100 000 in 2019). We also found unfavourable trends among HIV-negative middle-aged (35-55) adults of India, men over 50 in the HIV-negative population and whole HIV-positive population of South Africa, and women aged 45-55 years of Russia. China had little progress in its HIV-positive population with worsening period risks from 2010 to 2019, and higher risks in the younger cohorts born after 1980.

INTERPRETATION

BRICS' actions on controlling tuberculosis achieved positive results, but the overall improvements were less than those in high-income Asia Pacific countries. BRICS and other high-burden countries should strengthen specified public health approaches and policies targeted at different priority groups in each country.

FUNDING

National Natural Science Foundation of China (82073573; 72074009), Peking University Global Health and Infectious Diseases Group.

Eliciting national and subnational sets of disability weights in mainland China: Findings from the Chinese disability weight measurement study

BACKGROUND

The disability weight (DW) quantifies the severity of health states from disease sequela and is a pivotal parameter for disease burden calculation. We conducted a national and subnational DW measurement in China.

METHODS

In 2020-2021, we conducted a web-based survey to assess DWs for 206 health states in 31 Chinese provinces targeting health workers via professional networks. We fielded questions of paired comparison (PC) and population health equivalence (PHE). The PC data were analysed by probit regression analysis, and the regression results were anchored by results from the PHE responses on the DW scale between 0 (no loss of health) and 1 (health loss equivalent to death).

FINDINGS

We used PC responses from 468,541 respondents to estimate DWs of health states. Eight of 11 domains of health had significantly negative coefficients in the regression of the difference between Chinese and Global Burden of Disease (GBD) DWs, suggesting lower DW values for health states with mention of these domains in their lay description. We noted considerable heterogeneity within domains, however. After applying these Chinese DWs to the 2019 GBD estimates for China, total years lived with disability (YLDs) increased by 14·9% to 177 million despite lower estimates for musculoskeletal disorders, cardiovascular diseases, mental disorders, diabetes and chronic kidney disease. The lower estimates of YLDs for these conditions were more than offset by higher estimates of common, low-severity conditions.

INTERPRETATION

The differences between the GBD and Chinese DWs suggest that there might be some contextual factors influencing the valuation of health states. While the reduced estimates for mental disorders, alcohol use disorder, and dementia could hint at a culturally different valuation of these conditions in China, the much greater shifts in YLDs from low-severity conditions more likely reflects methodological difficulty to distinguish between health states that vary a little in absolute DW value but a lot in relative terms.

FUNDING

This work was supported by the National Natural Science Foundation of China [grant number 82173626], the National Key Research and Development Program of China [grant numbers 2018YFC1315302], Wuhan Medical Research Program of Joint Fund of Hubei Health Committee [grant number WJ2019H304], and Ningxia Natural Science Foundation Project [grant number 2020AAC03436].

Predictive performance of international COVID-19 mortality forecasting models

Forecasts and alternative scenarios of COVID-19 mortality have been critical inputs into a range of policies and decision-makers need information about predictive performance. We identified n=386 public COVID-19 forecasting models and included n=8 that were global in scope and provided public, date-versioned forecasts. For each, we examined the median absolute percent error (MAPE) compared to subsequently observed mortality trends, stratified by weeks of extrapolation, world region, and month of model estimation. Models were also assessed for ability to predict the timing of peak daily mortality. The MAPE among models released in July rose from 1.8% at one week of extrapolation to 24.6% at twelve weeks. The MAPE at six weeks were the highest in Sub-Saharan Africa (34.8%), and the lowest in high-income countries (6.3%). At the global level, several models had about 10% MAPE at six weeks, showing surprisingly good performance despite the complexities of modelling human behavioural responses and government interventions. The framework and publicly available codebase presented here ( https://github.com/pyliu47/covidcompare ) can be routinely used to compare predictions and evaluate predictive performance in an ongoing fashion.

Mapping of variations in child stunting, wasting and underweight within the states of India: the Global Burden of Disease Study 2000-2017

BACKGROUND

To inform actions at the district level under the National Nutrition Mission (NNM), we assessed the prevalence trends of child growth failure (CGF) indicators for all districts in India and inequality between districts within the states.

METHODS

We assessed the trends of CGF indicators (stunting, wasting and underweight) from 2000 to 2017 across the districts of India, aggregated from 5 × 5 km grid estimates, using all accessible data from various surveys with subnational geographical information. The states were categorised into three groups using their Socio-demographic Index (SDI) levels calculated as part of the Global Burden of Disease Study based on per capita income, mean education and fertility rate in women younger than 25 years. Inequality between districts within the states was assessed using coefficient of variation (CV). We projected the prevalence of CGF indicators for the districts up to 2030 based on the trends from 2000 to 2017 to compare with the NNM 2022 targets for stunting and underweight, and the WHO/UNICEF 2030 targets for stunting and wasting. We assessed Pearson correlation coefficient between two major national surveys for district-level estimates of CGF indicators in the states.

FINDINGS

The prevalence of stunting ranged 3.8-fold from 16.4% (95% UI 15.2-17.8) to 62.8% (95% UI 61.5-64.0) among the 723 districts of India in 2017, wasting ranged 5.4-fold from 5.5% (95% UI 5.1-6.1) to 30.0% (95% UI 28.2-31.8), and underweight ranged 4.6-fold from 11.0% (95% UI 10.5-11.9) to 51.0% (95% UI 49.9-52.1). 36.1% of the districts in India had stunting prevalence 40% or more, with 67.0% districts in the low SDI states group and only 1.1% districts in the high SDI states with this level of stunting. The prevalence of stunting declined significantly from 2010 to 2017 in 98.5% of the districts with a maximum decline of 41.2% (95% UI 40.3-42.5), wasting in 61.3% with a maximum decline of 44.0% (95% UI 42.3-46.7), and underweight in 95.0% with a maximum decline of 53.9% (95% UI 52.8-55.4). The CV varied 7.4-fold for stunting, 12.2-fold for wasting, and 8.6-fold for underweight between the states in 2017; the CV increased for stunting in 28 out of 31 states, for wasting in 16 states, and for underweight in 20 states from 2000 to 2017. In order to reach the NNM 2022 targets for stunting and underweight individually, 82.6% and 98.5% of the districts in India would need a rate of improvement higher than they had up to 2017, respectively. To achieve the WHO/UNICEF 2030 target for wasting, all districts in India would need a rate of improvement higher than they had up to 2017. The correlation between the two national surveys for district-level estimates was poor, with Pearson correlation coefficient of 0.7 only in Odisha and four small north-eastern states out of the 27 states covered by these surveys.

INTERPRETATION

CGF indicators have improved in India, but there are substantial variations between the districts in their magnitude and rate of decline, and the inequality between districts has increased in a large proportion of the states. The poor correlation between the national surveys for CGF estimates highlights the need to standardise collection of anthropometric data in India. The district-level trends in this report provide a useful reference for targeting the efforts under NNM to reduce CGF across India and meet the Indian and global targets.

A de-identified database of 11,979 verbal autopsy open-ended responses

As part of the Gates Grand Challenge 13, the Population Health Metrics Research Consortium (PHMRC) collected data to enable the development and validation of methods that measure cause-specific mortality in populations with incomplete or inadequate cause of death coding. This work yielded 11,979 verbal autopsy interviews (VAIs). In each, a field interviewer spoke with an individual familiar with the deceased and their final illness, and used a semi-structured questionnaire to collect information about the symptoms of the deceased in their final illness. The VAI collected demographic characteristics, possible risk factors (such as tobacco use), and other potentially contributing characteristics. It also included the open-ended question, "Could you please summarize, or tell us in your own words, any additional information about the illness and/or death of your loved one?" (open narrative). The VAI data were released in a de-identified format in September 2013 through the Global Health Data Exchange, in files that contain verbal autopsies that were collected at six sites in four countries (India, Mexico, Tanzania, and the Philippines). Due to research interest, we have now created redacted versions of the open narratives from the open-ended question of the questionnaire. We hope that this database will be the source of innovations that increase our knowledge about the causes of ill health and, through this knowledge, produce improvements in health for individuals and populations.

Stroke Prevalence, Mortality and Disability-Adjusted Life Years in Children and Youth Aged 0-19 Years: Data from the Global and Regional Burden of Stroke 2013

Background: There is increasing recognition of stroke as an important contributor to childhood morbidity and mortality. Current estimates of global childhood stroke burden and its temporal trends are sparse. Accurate and up-to-date estimates of childhood stroke burden are important for planning research and the resulting evidence-based strategies for stroke prevention and management. Objectives: To estimate the prevalence, mortality and disability-adjusted life years (DALYs) for ischemic stroke (IS), hemorrhagic stroke (HS) and all stroke types combined globally from 1990 to 2013. Methodology: Stroke prevalence, mortality and DALYs were estimated using the Global Burden of Disease 2013 methods. All available data on stroke-related incidence, prevalence, excess mortality and deaths were collected. Statistical models and country-level covariates were employed to produce comprehensive and consistent estimates of prevalence and mortality. Stroke-specific disability weights were used to estimate years lived with disability and DALYs. Means and 95% uncertainty intervals (UIs) were calculated for prevalence, mortality and DALYs. The median of the percent change and 95% UI were determined for the period from 1990 to 2013. Results: In 2013, there were 97,792 (95% UI 90,564-106,016) prevalent cases of childhood IS and 67,621 (95% UI 62,899-72,214) prevalent cases of childhood HS, reflecting an increase of approximately 35% in the absolute numbers of prevalent childhood strokes since 1990. There were 33,069 (95% UI 28,627-38,998) deaths and 2,615,118 (95% UI 2,265,801-3,090,822) DALYs due to childhood stroke in 2013 globally, reflecting an approximately 200% decrease in the absolute numbers of death and DALYs in childhood stroke since 1990. Between 1990 and 2013, there were significant increases in the global prevalence rates of childhood IS, as well as significant decreases in the global death rate and DALYs rate of all strokes in those of age 0-19 years. While prevalence rates for childhood IS and HS decreased significantly in developed countries, a decline was seen only in HS, with no change in prevalence rates of IS, in developing countries. The childhood stroke DALY rates in 2013 were 13.3 (95% UI 10.6-17.1) for IS and 92.7 (95% UI 80.5-109.7) for HS per 100,000. While the prevalence of childhood IS compared to childhood HS was similar globally, the death rate and DALY rate of HS was 6- to 7-fold higher than that of IS. In 2013, the prevalence rate of both childhood IS and HS was significantly higher in developed countries than in developing countries. Conversely, both death and DALY rates for all stroke types were significantly lower in developed countries than in developing countries in 2013. Men showed a trend toward higher childhood stroke death rates (1.5 (1.3-1.8) per 100,000) than women (1.1 (0.9-1.5) per 100,000) and higher childhood stroke DALY rates (120.1 (100.8-143.4) per 100,000) than women (90.9 (74.6-122.4) per 100,000) globally in 2013. Conclusions: Globally, between 1990 and 2013, there was a significant increase in the absolute number of prevalent childhood strokes, while absolute numbers and rates of both deaths and DALYs declined significantly. The gap in childhood stroke burden between developed and developing countries is closing; however, in 2013, childhood stroke burden in terms of absolute numbers of prevalent strokes, deaths and DALYs remained much higher in developing countries. There is an urgent need to address these disparities with both global and country-level initiatives targeting prevention as well as improved access to acute and chronic stroke care.

Selective targeting of a laccase from Stachybotrys chartarum covalently linked to a carotenoid-binding peptide

Atwo-step targeting strategy was used to identify improved laccases for bleaching carotenoid-containing stains on fabric. We first applied a modified phage display technique to identify peptide sequences capable of binding specifically to carotenoid stains and not to fabric. Prior deselection on the support on which the carotenoid was localized, increased stringency during the biopanning target selection process, and analysis of the phage peptides' binding to the target after acid elution and polymerase chain reaction (PCR) postacid elution, were used to isolate phage peptide libraries with increased binding selectivity and affinity. Peptide sequences were selected based on identified consensus motifs. We verified the enhanced carotenoid-binding properties of the peptide YGYLPSR and subsequently cloned and expressed C-terminal variants of laccase from Stachybotrys chartarum containing carotenoid-binding peptides YGYLPSR, IERSAPATAPPP, KASAPAL, CKASAPALC, and SLLNATK. These targeted peptide-laccase fusions demonstrate enhanced catalytic properties on stained fabrics.

Uterine preservation or hysterectomy at sacrospinous colpopexy for uterovaginal prolapse?

This study retrospectively compared 34 women who had a sacrospinous hysteropexy and 36 who had a vaginal hysterectomy and sacrospinous fixation for symptomatic uterine prolapse. All women underwent independent review and examination, with a mean follow-up of 36 months in the hysterectomy group and 26 months in the hysteropexy group. The subjective success rate was 86% in the hysterectomy group and 78% in the hysteropexy group (P = 0.70). The objective success rate was 72% and 74%, respectively (P = 1.00). The patient-determined satisfaction rate was 86% in the hysterectomy group and 85% in the hysteropexy group (P = 1.00). The operating time in the hysterectomy group was 91 minutes, compared to 59 minutes in the hysteropexy group (P < 0.01). The mean intraoperative blood loss in the hysterectomy group was 402 ml, compared to 198 ml in the hysteropexy group (P < 0.01). The sacrospinous hysteropexy is effective in the treatment of uterine prolapse. Vaginal hysterectomy may not be necessary in the surgical treatment of uterine prolapse.

Measuring quality: from the system to the provider

The literature on quality has often focused on process indicators. In this paper we outline a framework for describing and measuring the quality of health systems in terms of a set of desirable outcomes. We illustrate how it can be measured using data collected from a recent evaluation of health system performance conducted by the World Health Organization (WHO). We then explore the extent to which this framework can be used to measure quality for all components of the system; for example, regions, districts, hospitals, and providers. There are advantages and disadvantages to defining quality in terms of outcomes rather than process indicators. The advantage is that it focuses the attention of policy makers on whether systems are achieving the desired goals. In fact, without the ability to measure outcomes it is not possible to be sure that process changes actually improve attainment of socially desired goals. The disadvantage is that measuring outcomes at all levels of the system poses some problems particularly related to the sample sizes necessary to measure outcomes. WHO is exploring this, initially in relation to hospitals. The paper discusses two major challenges. The first is the question of attribution, deciding what part of the outcome is due to the component of the system under discussion. The second is the question of timing, including all the effects of current health actions now and in the future.

Comparative efficiency of national health systems: cross national econometric analysis

OBJECTIVE

To improve the evidence base for health policy by devising a method to measure and monitor the performance of health systems.

DESIGN

Estimation of the relation between levels of population health and the inputs used to produce health.

SETTING

191 countries.

MAIN OUTCOME MEASURE

Health system efficiency (performance).

RESULTS

Estimated efficiency varied from nearly fully efficient to nearly fully inefficient. Countries with a history of civil conflict or high prevalence of HIV and AIDS were less efficient. Performance increased with health expenditure per capita.

CONCLUSIONS

Increasing the resources for health systems is critical to improving health in poor countries, but important gains can be made in most countries by using existing resources more efficiently.

Stochastic league tables: communicating cost-effectiveness results to decision-makers

The presentation of the results of uncertainty analysis in cost-effectiveness analysis (CEA) in the literature has been relatively academic with little attention paid to the question of how decision-makers should interpret the information particularly when confidence intervals overlap. This question is especially relevant to sectorial CEA providing information on the costs and effects of a wide range of interventions. This paper introduces stochastic league tables to inform decision-makers about the probability that a specific intervention would be included in the optimal mix of interventions for various levels of resource availability, taking into account the uncertainty surrounding costs and effectiveness. This information helps decision-makers decide on the relative attractiveness of different intervention mixes, and also on the implications for trading gains in efficiency for gains in other goals such as reducing health inequalities and increasing health system responsiveness.

Iliococcygeus or sacrospinous fixation for vaginal vault prolapse

OBJECTIVE

To compare iliococcygeus (prespinous) and sacrospinous fixation for vaginal vault prolapse.

METHODS

Between 1994 and 1998, 78 women underwent sacrospinous colpopexy and 50 underwent iliococcygeus fixation for the management of symptomatic vaginal vault prolapse. A matched case-control study was designed to compare the two approaches. The matched variables included age, parity, body mass index, degree of vault prolapse, menopause, sexual activity, constipation, previous prolapse or continence surgery, stress incontinence, and length of review. Thirty-six matched pairs were isolated, resulting in a study with a power of 50% to detect a 20% difference in the success rates between the two groups.

RESULTS

The subjective success rate for the iliococcygeus group was 91%; it was 94% for the sacrospinous group (P =.73). The objective success rate was 53% and 67% (P =.36), and the patient satisfaction with surgery was 78 of 100 and 91 of 100 (P =.01) on a visual analogue scale. The mean length of postoperative follow-up was 21 months for the iliococcygeus group and 19 months for the sacrospinous group (P =.52). The recovery time was 54 days in the iliococcygeus group and 39 days in the sacrospinous group (P =.04). No significant difference was seen in the incidence of postoperative cystoceles or damage to the pudendal neurovascular bundle.

CONCLUSION

Sacrospinous and iliococcygeus fixation are equally effective procedures for vaginal vault prolapse and have similar rates of postoperative cystocele, buttock pain, and hemorrhage requiring transfusion. The sacrospinous ligament fixation should not be discarded in favor of the iliococcygeus fixation in the management of vaginal vault prolapse.

Laparoscopic suture hysteropexy for uterine prolapse

OBJECTIVE

Vaginal hysterectomy remains the accepted surgical treatment for women with uterine prolapse. The Manchester repair is favored in women wishing uterine preservation. Vaginal hysterectomy alone fails to address the pathologic cause of the uterine prolapse. The Manchester repair has a high failure rate and may cause difficulty sampling the cervix and uterus in the future. The laparoscopic suture hysteropexy offers physiologic repair of uterine prolapse.

METHOD

At the laparoscopic suture hysteropexy, the pouch of Douglas is closed and the uterosacral ligaments are plicated and reattached to the cervix.

RESULTS

Forty-three women with symptomatic uterine prolapse were prospectively evaluated and underwent laparoscopic suture hysteropexy with a mean follow-up of 12 +/- 7 months (range 6-32). The mean operating time for the laparoscopic suture hysteropexy alone was 42 +/- 15 minutes (range 22-121), and the mean blood loss was less than 50 mL. On review, 35 women (81%) had no symptoms of prolapse and 34 (79%) had no objective evidence of uterine prolapse. Two women subsequently completed term pregnancies and were without prolapse. Both underwent elective cesarean delivery.

CONCLUSION

The laparoscopic suture hysteropexy is effective and safe in the management of symptomatic uterine prolapse. The result is physiologically correct, without disfiguring the cervix. This may be an appropriate procedure for women with uterine prolapse wishing uterine preservation.

Healthy life expectancy in 191 countries, 1999

We describe here the methods used to produce the first estimates of healthy life expectancy (DALE) for 191 countries in 1999. These were based on estimates of the incidence, prevalence, and disability distributions for 109 disease and injury causes by age group, sex, and region of the world, and an analysis of 60 representative health surveys across the world. We used Sullivan's method to compute healthy life expectancy for men and women in each WHO member country. Japan had the highest average healthy life expectancy of 74.5 years at birth in 1999. The bottom ten countries are all in sub-Saharan Africa, where the HIV-AIDS epidemic is most prevalent, resulting in DALE at birth of less than 35 years. Years of healthy life lost due to disability represent 18% of total life expectancy in the bottom countries, and decreases to around 8% in the countries with the highest healthy life expectancies. Globally, the male-female gap is lower for DALE than for total life expectancy. Healthy life expectancy increases across countries at a faster rate than total life expectancy, suggesting that reductions in mortality are accompanied by reductions in disability. Although women live longer, they spend a greater amount of time with disability. As average levels of health expenditure per capita increase, healthy life expectancy increases at a greater rate than total life expectancy.

Modeling the effects of health on economic growth

This paper investigates the effects of health indicators such as adult survival rates (ASR) on GDP growth rates at 5-year intervals in several countries. Panel data were analyzed on GDP series based on purchasing power adjustments and on exchange rates. First, we developed a framework for modeling the inter-relationships between GDP growth rates and explanatory variables by re-examining the life expectancy-income relationship. Second, models for growth rates were estimated taking into account the interaction between ASR and lagged GDP level; issues of endogeneity and reverse causality were addressed. Lastly, we computed confidence intervals for the effect of ASR on growth rate and applied a test for parameter stability. The results showed positive effects of ASR on GDP growth rates in low-income countries.

Burden of disease--implications for future research

One overall challenge for public health and medicine in the future is to allocate available resources effectively to reduce major causes of disease burden globally and to decrease health disparities between poor and affluent populations. The major risk factors for death and disability worldwide are malnutrition; poor water supply, sanitation, and personal and domestic hygiene; unsafe sexual behavior; tobacco use; alcohol use; occupational hazards; hypertension; physical inactivity; illicit drugs; and air pollution. The challenge for research in the 21st century is to maintain and improve life expectancy and the quality of life that was achieved for most of the world's population during the 20th century.

Modelling HIV/AIDS epidemics in sub-Saharan Africa using seroprevalence data from antenatal clinics

OBJECTIVE

To improve the methodological basis for modelling the HIV/AIDS epidemics in adults in sub-Saharan Africa, with examples from Botswana, Central African Republic, Ethiopia, and Zimbabwe. Understanding the magnitude and trajectory of the HIV/AIDS epidemic is essential for planning and evaluating control strategies.

METHODS

Previous mathematical models were developed to estimate epidemic trends based on sentinel surveillance data from pregnant women. In this project, we have extended these models in order to take full advantage of the available data. We developed a maximum likelihood approach for the estimation of model parameters and used numerical simulation methods to compute uncertainty intervals around the estimates.

FINDINGS

In the four countries analysed, there were an estimated half a million new adult HIV infections in 1999 (range: 260 to 960 thousand), 4.7 million prevalent infections (range: 3.0 to 6.6 million), and 370 thousand adult deaths from AIDS (range: 266 to 492 thousand).

CONCLUSION

While this project addresses some of the limitations of previous modelling efforts, an important research agenda remains, including the need to clarify the relationship between sentinel data from pregnant women and the epidemiology of HIV and AIDS in the general population.

State-space modeling of the relationship between air quality and mortality

A portion of a population is assumed to be at risk, with the mortality hazard varying with atmospheric conditions including total suspended particulates (TSP). This at-risk population is not observed and the hazard function is unknown; we wish to estimate these from mortality count and atmospheric variables. Consideration of population dynamics leads to a state-space representation, allowing the Kalman Filter (KF) to be used for estimation. A harvesting effect is thus implied; high mortality is followed by lower mortality until the population is replenished by new arrivals. The model is applied to daily data for Philadelphia, PA, 1973-1990. The estimated hazard function rises with the level of TSP and at extremes of temperature and also reflects a positive interaction between TSP and temperature. The estimated at-risk population averages about 480 and varies seasonally. We find that lags of TSP are statistically significant, but the presence of negative coefficients suggests their role may be partially statistical rather than biological. In the population dynamics framework, the natural metric for health damage from air pollution is its impact on life expectancy. The range of hazard rates over the sample period is 0.07 to 0.085, corresponding to life expectancies of 14.3 and 11.8 days, respectively.

Epidemiology of participation: an Australian community study

STUDY OBJECTIVE

To determine the levels of participation in social and civic community life in a metropolitan region, and to assess differential levels of participation according to demographic, socioeconomic and health status. To contribute to policy debates on community participation, social capital and health using these empirical data.

DESIGN

Cross sectional, postal, self completed survey on health and participation.

SETTING

Random sample of the population from the western suburbs of Adelaide, the capital city of South Australia, a population of approximately 210 000.

PARTICIPANTS

2542 respondents from a sample of 4000 people aged 18 years and over who were registered on the electoral roll.

MAIN RESULTS

The response rate to the survey was 63.6% (n=2542). Six indices of participation, on range of social and civic activities, with a number of items in each, were created. Levels of participation were highest in the informal social activities index (46.7-83.7% for individual items), and lowest in the index of civic activities of a collective nature (2.4-5.9% for individual items). Low levels of involvement in social and civic activities were reported more frequently by people of low income and low education levels.

CONCLUSIONS

Levels of participation in social and civic community life in an urban setting are significantly influenced by individual socioeconomic status, health and other demographic characteristics. An understanding of the pattern of participation is important to inform social and health policy making. Increasing levels of participation will reduce social exclusion and is likely to improve the overall quality of community life.

Development of WHO guidelines on generalized cost-effectiveness analysis

The growing use of cost-effectiveness analysis (CEA) to evaluate specific interventions is dominated by studies of prospective new interventions compared with current practice. This type of analysis does not explicitly take a sectoral perspective in which the costs and effectiveness of all possible interventions are compared, in order to select the mix that maximizes health for a given set of resource constraints. WHO guidelines on generalized CEA propose the application of CEA to a wide range of interventions to provide general information on the relative costs and health benefits of different interventions in the absence of various highly local decision constraints. This general approach will contribute to judgements on whether interventions are highly cost-effective, highly cost-ineffective, or something in between. Generalized CEAs require the evaluation of a set of interventions with respect to the counterfactual of the null set of the related interventions, i.e. the natural history of disease. Such general perceptions of relative cost-effectiveness, which do not pertain to any specific decision-maker, can be a useful reference point for evaluating the directions for enhancing allocative efficiency in a variety of settings. The proposed framework allows the identification of current allocative inefficiencies as well as opportunities presented by new interventions.

A framework for assessing the performance of health systems

Health systems vary widely in performance, and countries with similar levels of income, education and health expenditure differ in their ability to attain key health goals. This paper proposes a framework to advance the understanding of health system performance. A first step is to define the boundaries of the health system, based on the concept of health action. Health action is defined as any set of activities whose primary intent is to improve or maintain health. Within these boundaries, the concept of performance is centred around three fundamental goals: improving health, enhancing responsiveness to the expectations of the population, and assuring fairness of financial contribution. Improving health means both increasing the average health status and reducing health inequalities. Responsiveness includes two major components: (a) respect for persons (including dignity, confidentiality and autonomy of individuals and families to decide about their own health); and (b) client orientation (including prompt attention, access to social support networks during care, quality of basic amenities and choice of provider). Fairness of financial contribution means that every household pays a fair share of the total health bill for a country (which may mean that very poor households pay nothing at all). This implies that everyone is protected from financial risks due to health care. The measurement of performance relates goal attainment to the resources available. Variation in performance is a function of the way in which the health system organizes four key functions: stewardship (a broader concept than regulation); financing (including revenue collection, fund pooling and purchasing); service provision (for personal and non-personal health services); and resource generation (including personnel, facilities and knowledge). By investigating these four functions and how they combine, it is possible not only to understand the proximate determinants of health system performance, but also to contemplate major policy challenges.

A critical examination of summary measures of population health

In the past decade, interest has been rising in the development, calculation and use of summary measures of population health, which combine information on mortality and non-fatal health outcomes. This paper reviews the issues and challenges in the design and application of summary measures and presents a framework for evaluating different alternatives. Summary measures have a variety of uses, including comparisons of health in different populations and assessments of the relative contributions of different diseases, injuries and risk factors to the total disease burden in a population. Summary measures may be divided into two broad families: health expectancies and health gaps. Within each family, there are many different possible measures, but they share a number of inputs, including information on mortality, non-fatal health outcomes, and health state valuations. Other critical points include calculation methods and a range of conceptual and methodological issues regarding the definition, measurement and valuation of health states. This paper considers a set of basic criteria and desirable properties that may lead to rejection of certain summary measures and the development of new ones. Despite the extensive developmental agenda that remains, applications of summary measures cannot await the final resolution of all methodological issues, so they should focus on those measures that satisfy as many basic criteria and desirable properties as possible.

Defining and measuring health inequality: an approach based on the distribution of health expectancy

This paper proposes an approach to conceptualizing and operationalizing the measurement of health inequality, defined as differences in health across individuals in the population. We propose that health is an intrinsic component of well-being and thus we should be concerned with inequality in health, whether or not it is correlated with inequality in other dimensions of well-being. In the measurement of health inequality, the complete range of fatal and non-fatal health outcomes should be incorporated. This notion is operationalized through the concept of healthy lifespan. Individual health expectancy is preferable, as a measurement, to individual healthy lifespan, since health expectancy excludes those differences in healthy lifespan that are simply due to chance. In other words, the quantity of interest for studying health inequality is the distribution of health expectancy across individuals in the population. The inequality of the distribution of health expectancy can be summarized by measures of individual/mean differences (differences between the individual and the mean of the population) or inter-individual differences. The exact form of the measure to summarize inequality depends on three normative choices. A firmer understanding of people's views on these normative choices will provide a basis for deliberating on a standard WHO measure of health inequality.

On the comparable quantification of health risks: lessons from the Global Burden of Disease Study

Extensive discussion and comments on the Global Burden of Disease Study findings have suggested the need to examine more carefully the basis for comparing the magnitude of different health risks. Attributable burden can be defined as the difference between burden currently observed and burden that would have been observed under an alternative population distribution of exposure. Population distributions of exposure may be defined over many different levels and intensities of exposure (such as systolic or diastolic blood pressure on a continuous scale), and the comparison distribution of exposure need not be zero. Avoidable burden is defined as the reduction in the future burden of disease if the current levels of exposure to a risk factor were reduced to those specified by the counterfactual distribution of exposure. Choosing the alternative population distribution for a variable, the counterfactual distribution of exposure, is the critical step in developing a more general and standardized concept of comparable, attributable, or avoidable burden. We have identified four types of distributions of exposure that could be used as the counterfactual distributions: theoretical minimum risk, plausible minimum risk, feasible minimum risk, and cost-effective minimum risk. Using tobacco and alcohol as examples, we explore the implications of using these different types of counterfactual distributions to define attributable and avoidable burden. The ten risk factor assessments included in the Global Burden of Disease Study reflect a range of methods and counterfactual distributions. We recommend that future assessments should focus on avoidable and attributable burden based on the plausible minimum risk counterfactual distribution of exposure.

Health inequalities and social group differences: what should we measure?

Both health inequalities and social group health differences are important aspects of measuring population health. Despite widespread recognition of their magnitude in many high- and low-income countries, there is considerable debate about the meaning and measurement of health inequalities, social group health differences and inequities. The lack of standard definitions, measurement strategies and indicators has and will continue to limit comparisons--between and within countries, and over time--of health inequalities, and perhaps more importantly comparative analyses of their determinants. Such comparative work, however, will be essential to find effective policies for governments to reduce health inequalities. This article addresses the question of whether we should be measuring health inequalities or social group health differences. To help clarify the strengths and weaknesses of these two approaches, we review some of the major arguments for and against each of them.

Modeling the impact of global tuberculosis control strategies

An epidemiological model of tuberculosis has been developed and applied to five regions of the world. Globally, 6.7 million new cases of tuberculosis and 2.4 million deaths from tuberculosis are estimated for 1998. Based on current trends in uptake of the World Health Organization's strategy of directly observed treatment, short-course, we expect a total of 225 million new cases and 79 million deaths from tuberculosis between 1998 and 2030. Active case-finding by using mass miniature radiography could save 23 million lives over this period. A single contact treatment for tuberculosis could avert 24 million cases and 11 million deaths; combined with active screening, it could reduce mortality by nearly 40%. A new vaccine with 50% efficacy could lower incidence by 36 million cases and mortality by 9 million deaths. Support for major extensions to global tuberculosis control strategies will occur only if the size of the problem and the potential for action are recognized more widely.

Understanding DALYs (disability-adjusted life years)

The measurement unit disability-adjusted life years (DALYs), used in recent years to quantify the burden of diseases, injuries and risk factors on human populations, is grounded on cogent economic and ethical principles and can guide policies toward delivering more cost-effective and equitable health care. DALYs follow from a fairness principle that treats 'like as like' within an information set comprising the health conditions of individuals, differentiated solely by age and sex. The particular health state weights used to account for non-fatal health outcomes are derived through the application of various forms of the person trade-off.

Alternative projections of mortality and disability by cause 1990-2020: Global Burden of Disease Study

BACKGROUND

Plausible projections of future mortality and disability are a useful aid in decisions on priorities for health research, capital investment, and training. Rates and patterns of ill health are determined by factors such as socioeconomic development, educational attainment, technological developments, and their dispersion among populations, as well as exposure to hazards such as tobacco. As part of the Global Burden of Disease Study (GBD), we developed three scenarios of future mortality and disability for different age-sex groups, causes, and regions.

METHODS

We used the most important disease and injury trends since 1950 in nine cause-of-death clusters. Regression equations for mortality rates for each cluster by region were developed from gross domestic product per person (in international dollars), average number of years of education, time (in years, as a surrogate for technological change), and smoking intensity, which shows the cumulative effects based on data for 47 countries in 1950-90. Optimistic, pessimistic, and baseline projections of the independent variables were made. We related mortality from detailed causes to mortality from a cause cluster to project more detailed causes. Based on projected numbers of deaths by cause, years of life lived with disability (YLDs) were projected from different relation models of YLDs to years of life lost (YLLs). Population projections were prepared from World Bank projections of fertility and the projected mortality rates.

FINDINGS

Life expectancy at birth for women was projected to increase in all three scenarios; in established market economies to about 90 years by 2020. Far smaller gains in male life expectancy were projected than in females; in formerly socialist economies of Europe, male life expectancy may not increase at all. Worldwide mortality from communicable maternal, perinatal, and nutritional disorders was expected to decline in the baseline scenario from 17.2 million deaths in 1990 to 10.3 million in 2020. We projected that non-communicable disease mortality will increase from 28.1 million deaths in 1990 to 49.7 million in 2020. Deaths from injury may increase from 5.1 million to 8.4 million. Leading causes of disability-adjusted life years (DALYs) predicted by the baseline model were (in descending order): ischaemic heart disease, unipolar major depression, road-traffic accidents, cerebrovascular disease, chronic obstructive pulmonary disease, lower respiratory infections, tuberculosis, war injuries, diarrhoeal diseases, and HIV. Tobacco-attributable mortality is projected to increase from 3.0 million deaths in 1990 to 8.4 million deaths in 2020.

INTERPRETATION

Health trends in the next 25 years will be determined mainly by the ageing of the world's population, the decline in age-specific mortality rates from communicable, maternal, perinatal, and nutritional disorders, the spread of HIV, and the increase in tobacco-related mortality and disability. Projections, by their nature, are highly uncertain, but we found some robust results with implications for health policy.

Global mortality, disability, and the contribution of risk factors: Global Burden of Disease Study

BACKGROUND

Prevention and control of disease and injury require information about the leading medical causes of illness and exposures or risk factors. The assessment of the public-health importance of these has been hampered by the lack of common methods to investigate the overall, worldwide burden. The Global Burden of Disease Study (GBD) provides a standardised approach to epidemiological assessment and uses a standard unit, the disability-adjusted life year (DALY), to aid comparisons.

METHODS

DALYs for each age-sex group in each GBD region for 107 disorders were calculated, based on the estimates of mortality by cause, incidence, average age of onset, duration, and disability severity. Estimates of the burden and prevalence of exposure in different regions of disorders attributable to malnutrition, poor water supply, sanitation and personal and domestic hygiene, unsafe sex, tobacco use, alcohol, occupation, hypertension, physical inactivity, use of illicit drugs, and air pollution were developed.

FINDINGS

Developed regions account for 11.6% of the worldwide burden from all causes of death and disability, and account for 90.2% of health expenditure worldwide. Communicable, maternal, perinatal, and nutritional disorders explain 43.9%; non-communicable causes 40.9%; injuries 15.1%; malignant neoplasms 5.1%; neuropsychiatric conditions 10.5%; and cardiovascular conditions 9.7% of DALYs worldwide. The ten leading specific causes of global DALYs are, in descending order, lower respiratory infections, diarrhoeal diseases, perinatal disorders, unipolar major depression, ischaemic heart disease, cerebrovascular disease, tuberculosis, measles, road-traffic accidents, and congenital anomalies. 15.9% of DALYs worldwide are attributable to childhood malnutrition and 6.8% to poor water, and sanitation and personal and domestic hygiene.

INTERPRETATION

The three leading contributors to the burden of disease are communicable and perinatal disorders affecting children. The substantial burdens of neuropsychiatric disorders and injuries are under-recognised. The epidemiological transition in terms of DALYs has progressed substantially in China, Latin America and the Caribbean, other Asia and islands, and the middle eastern crescent. If the burdens of disability and death are taken into account, our list differs substantially from other lists of the leading causes of death. DALYs provide a common metric to aid meaningful comparison of the burden of risk factors, diseases, and injuries.

Regional patterns of disability-free life expectancy and disability-adjusted life expectancy: global Burden of Disease Study

BACKGROUND

Information on non-fatal health outcomes of disease and injury has been largely neglected in health planning because of the conceptual and definitional complexity of measuring morbidity and disability in populations. One of our major objectives was to quantify disability for inclusion in health policy debates. We analysed these health outcomes in terms of disability-free life expectancy (DFLE) and disability-adjusted life expectancy (DALE).

METHODS

Published and unpublished data were systematically reviewed to estimate the incidence, prevalence, and duration of 483 disabling sequelae of 107 diseases and injuries. To ensure internal consistency of these estimates, a software programme (DISMOD) was applied many times until consistent parameters were identified. The severity of disability, on a scale of 0 (perfect health) to 1 (death), was measured in a deliberate manner by the person-trade-off method. Spearman's and Pearson's correlation coefficients were used to measure disability weights among groups. Prevalence of seven classes of disability was back-calculated from the distribution of each disabling sequela across disabilities. Prevalence for each class of disability for different age-sex groups was used to calculate seven forms of DFLE and DALE based on Sullivan's method.

FINDINGS

Prevalence of most disability classes is highest in sub-Saharan Africa and lowest in established market economies. Low-severity disabilities (class I and class II) are the most common. The expectation at birth of class I disability ranges from 6.5 years in established market economies to 14.7 years in sub-Saharan Africa, and for class II disabilities, from 8.5-18.4 years. DFLE varies significantly among regions: DFLE for class I disabilities at birth ranges from 9.9 years in sub-Saharan Africa to 47.7 years in established market economies for females and DFLE for class V disabilities ranges from 43.4 years for men in sub-Saharan Africa to 74.8 years for women in established market economies. The proportion of expected life span at birth lived with disability adjusted for severity, varies from about 8% in established market economies to 15% in sub-Saharan Africa, with little difference between men and women. In high-income regions, nearly 90% of expected disability is due to non-communicable diseases and most of the remainder to injuries. In poorer regions, almost half of expected disability is due to communicable diseases and injuries.

INTERPRETATION

The higher proportion of lifespan spent disabled in high-mortality populations is consistent with the compression of morbidity hypothesis. The threshold definition of disability used substantially affects the results of DFLE, DALE, which incorporates severity weights for disabilities, is a useful summary measure of the burden of disability and mortality.

Mortality by cause for eight regions of the world: Global Burden of Disease Study

BACKGROUND

Reliable information on causes of death is essential to the development of national and international health policies for prevention and control of disease and injury. Medically certified information is available for less than 30% of the estimated 50.5 million deaths that occur each year worldwide. However, other data sources can be used to develop cause-of-death estimates for populations. To be useful, estimates must be internally consistent, plausible, and reflect epidemiological characteristics suggested by community-level data. The Global Burden of Disease Study (GBD) used various data sources and made corrections for miscoding of important diseases (eg, ischaemic heart disease) to estimate worldwide and regional cause-of-death.patterns in 1990 for 14 age-sex groups in eight regions, for 107 causes.

METHODS

Preliminary estimates were developed with available vital-registration data, sample-registration data for India and China, and small-scale population-study data sources. Registration data were corrected for miscoding, and Lorenz-curve analysis was used to estimate cause-of-death patterns in areas without registration. Preliminary estimates were modified to reflect the epidemiology of selected diseases and injuries. Final estimates were checked to ensure that numbers of deaths in specific age-sex groups did not exceed estimates suggested by independent demographic methods.

FINDINGS

98% of all deaths in children younger than 15 years are in the developing world. 83% and 59% of deaths at 15-59 and 70 years, respectively, are in the developing world. The probability of death between birth and 15 years ranges from 22.0% in sub-Saharan Africa to 1.1% in the established market economies. Probabilities of death between 15 and 60 years range from 7.2% for women in established market economies to 39.1% for men in sub-Saharan Africa. The probability of a man or woman dying from a non-communicable disease is higher in sub-Saharan Africa and other developing regions than in established market economies. Worldwide in 1990, communicable, maternal, perinatal, and nutritional disorders accounted for 17.2 million deaths, non-communicable diseases for 28.1 million deaths and injuries for 5.1 million deaths. The leading causes of death in 1990 were ischaemic heart disease (6.3 million deaths), cerebrovascular accidents (4.4 million deaths), lower respiratory infections (4.3 million), diarrhoeal diseases (2.9 million), perinatal disorders (2.4 million), chronic obstructive pulmonary disease (2.2 million), tuberculosis (2.0 million), measles (1.1 million), road-traffic accidents (1.0 million), and lung cancer (0.9 million).

INTERPRETATION

Five of the ten leading killers are communicable, perinatal, and nutritional disorders largely affecting children. Non-communicable diseases are, however, already major public health challenges in all regions. Injuries, which account for 10% of global mortality, are often ignored as a major cause of death and may require innovative strategies to reduce their toll. The estimates by cause have wide Cls, but provide a foundation for a more informed debate on public-health priorities.

Health expenditures in Latin America and the Caribbean

This paper presents the results of a study commissioned by the Latin American and Caribbean Technical Department of the World Bank to document and analyze health expenditures in Latin America and the Caribbean. In 1990, the countries of this region spent US$ 69 billion on health, with an average per capita health expenditure of US$ 162. On average, the countries spent 6.2% of their GDP on health, with the expenditures divided about equally between the public and private sectors. In both the public and private sectors, per capita health expenditures were positively and significantly correlated with per capita income. However, this relationship holds only for the public sector, when health expenditures are measured as a proportion of GDP. While several poorer countries were dependent on external assistance, with increasing income, the countries relied more on public expenditures to finance health care. Based on the limited time series data, it is evident that there was a considerable variation among countries regarding the proportion spent on capital investments, primary health care, and drugs, but not on salaries. Looking ahead, with increasing economic development, the proportion of GDP spent on health, along with public health expenditure as a proportion of total health expenditure, is likely to increase rapidly, while aid dependency is likely to decline.

The utility of DALYs for public health policy and research: a reply

The WHO Advisory Committee on Health Research (ACHR), through its DALY Review Group, has recently criticized the use of disability-adjusted life years (DALYs). To suggest that the use of DALYs should be discouraged as an aid in health resource allocation may, however, be premature, since it enhances informed debate on the social values that influence resource allocation, identifies health problems that may be neglected, and points to the strengths and weaknesses of existing health information systems.

A low-barrier hydrogen bond in subtilisin: 1H and 15N NMR studies with peptidyl trifluoromethyl ketones

The N delta 1 proton of His 64 forms a hydrogen bond with Asp 32, as part of the catalytic triad in serine proteases of the subtilisin family. His 64 in subtilisin has been studied by 1H and 15N NMR spectroscopy in the presence and absence of peptidyl trifluoromethyl ketones (TFMKs) that are transition state analog inhibitors. For subtilisin Carlsberg, the downfield resonance of the imidazolium N delta 1 proton is approximately 18.3 ppm and the D/H fractionation factor is 0.55 +/- 0.04 at pH 5.5 (11 degrees C), and 0.63 +/- 0.04 (5 degrees C) and 0.68 +/- 0.04 at pH 6 (11 degrees C). In the complex between subtilisin Carlsberg and Z-L-leucyl-L-leucyl-L-phenylalanyltrifluoromethyl ketone (Z-LLF-CF3) at pH values between 6.5 and 10.6, His 64 remains positively charged, and the D/H fractionation factor of its N delta 1 proton is 0.85 +/- 0.05. In the complex between a subtilisin variant from Bacillus lentus and Z-LLF-CF3, the proton resonance at 18.8 ppm is correlated with a 15N resonance at 197.6 ppm downfield from liquid NH3 with a 1JNH of 81 Hz. The chemical shifts of subtilisin complexes with peptidyl TFMKs are among the most downfield shifts reported for any protein. At pH 9.5, His 64 is neutral and the D/H fractionation factor increases to 1.2 with a chemical shift of 15.0. His 64 is positively charged in the free enzyme at low pH, the inhibitor hemiketal complex at neutral pH, and the transition state for amide bond hydrolysis. These data thus provide indirect evidence for the presence of a low-barrier hydrogen bond in the catalytic mechanism of subtilisin proteases.

Active-site titration of serine proteases using a fluoride ion selective electrode and sulfonyl fluoride inhibitors

We report a general procedure for the determination of active enzyme concentrations for serine proteases. The method relies on the measurement of fluoride ion released from sulfonyl fluorides upon reaction with the active-site serine using an ion selective electrode. The results have been independently confirmed by amino acid analyses of subtilisins and by spectrofluorometric and spectrophotometric titrations. The minimal enzyme concentration detectable is 1-10 microM protease. The method is insensitive to color and turbidity of the sample and is therefore useful for measuring protease concentration in broth solutions. The active enzyme concentration of subtilisin BPN' from Bacillus amyloliquefaciens determined by titration with phenylmethylsulfonyl fluoride is 25% higher than the concentration determined using the spectrophotometric burst titrant N-trans-cinnamoylimidazole. Analysis of the pre-steady-state burst amplitude and kinetics suggests that the extinction coefficient for the cinnamoyl acyl-enzyme is larger than previously measured and a significant fraction of the enzyme is present as an unproductive ES2 complex. The molar extinction coefficient at 280 nm for subtilisin BPN' is 26.5 mM-1 cm-1 and for subtilisin from Bacillus lentus is 22.5 mM-1 cm-1.

Secondary H/T and D/T isotope effects in enzymatic enolization reactions. Coupled motion and tunneling in the triosephosphate isomerase reaction

Secondary kH/kT kinetic isotope effects in H2O and kH/kT or kD/kT isotope effects in D2O have been measured for the triosephosphate isomerase-catalyzed conversion of dihydroxyacetone 3-phosphate (DHAP) to D-glyceraldehyde 3-phosphate. The proton transfer steps are made rate-limiting using [1(R)-2H]-labeled substrate in D2O to slow the chemical steps, relative to product release. After a small correction for the beta-equilibrium isotope effect for dehydration of DHAP, the H/T kinetic isotope effect kH/kT = 1.27 +/- 0.03 for [1(R)-2H,(S)-3H]-labeled substrate in D2O is subtantially larger than the equilibrium isotope effect for enolization of DHAP, KH/KT = 1.12. The H/T isotope effect is related to the D/T isotope effect with a Swain-Schaad exponent y = 4.4 +/- 1.3. These results are consistent with coupled motion of the C-1 primary and secondary hydrogens of DHAP and tunneling. Large secondary kinetic isotope effects are a general feature of enzymatic enolization reactions while nonenzymatic enolization reactions show secondary kinetic isotope effects that are substantially smaller than equilibrium effects [Alston, W. A., II, Haley, K., Kanski, R., Murray, C.J., & Pranata, J. (1996) J. Am. Chem Soc., 118, 6562-6569]. Possible origins for these differences in transition state structure are discussed.

The incremental effect of age-weighting on YLLs, YLDs, and DALYs: a response

When disability-adjusted life years (DALYs) were first formulated, the effect of age-weighting on years of life lost due to death at each age as well as the different effect on short- and medium-term disability were taken into consideration. While there is considerable scope for discussion on the actual values that are incorporated into DALYs, the present article argues that once the values have been chosen we should accept the consequences of the choice.

Toward an analytical approach to health sector reform

An analytical approach to health sector reform requires definition of the objectives of the health sector. Although a multiplicity of objectives may be appealing, there are compelling analytical reasons for simplicity. It is argued that a health status maximization objective is a widely acceptable choice, which captures most of the important aspects of utility maximization of relevance for health sector reform. Equity can be addressed in the process of aggregating individual outcomes. The widely recognized need for health sector reform in developing countries constitutes, in itself, evidence of the market failures in the health sector. If the market worked, why would we need reform? Given an objective and a justification for reform, analysis should proceed to address measurement questions and intervention strategies. The disability-adjusted life year lost is proposed as a consistent and feasible measure of health. Based on an optimization model of health sector performance in Africa, the paper discusses interventions to improve allocative and technical efficiency. These are broadly characterized as interventions dealing with lack of knowledge and interventions dealing with institutional shortcomings. They lead to different approaches to health sector reform. The paper concludes that we now have a systematic analytical approach to reform, in which tools and methods for addressing information gaps are well developed and need to be more widely applied, while those addressing institutional failures still need further development and application.