New estimates of the causes of child death under age 5

WHO has just released the latest update on global causes of death for children under age 5 for years 2000-2017. These are available for download on the WHO website at  https://www.who.int/healthinfo/global_burden_disease/estimates/en/index2.html and also in the Global Health Observatory at www.who.int/gho.  A collaborating group of academic researchers led by Professor Bob Black from Johns Hopkins University carried out data analysis and modelling in collaboration with a number of WHO technical departments and myself.

Despite remarkable progress in the improvement of child survival globally, with a reduction in the annual number of child deaths from 10 million in 2000 to 5.4 million in 2017, this level of progress will need to accelerate to achieve the Sustainable Development Goal for child mortality in 2030. There remain many preventable child deaths in developing countries. The causes of the 5.4 million deaths of children under 5 are summarized in the following pie chart.

Global distribution of causes of child death under age 5, 2017

 

Almost half of deaths under 5 are now in the neonatal period (the first four weeks of life) where the causes of death are shaded yellow above and led by prematurity and birth asphyxia or trauma.  In the period 1-11 months the leading cause of death is acute respiratory infection (ARI) which is mostly pneumonia, followed by diarrheal diseases and injuries.

Reductions in mortality rates for pneumonia, diarrhoea, neonatal intrapartum-related events, malaria, and measles were responsible for 65% of the total reduction of under 5 deaths, pr just under 3 million of the 4.6 million deaths per year averted between 2000 and 2017 (see Figure below). Most of these causes relate mainly to the period 1-59 months after the neonatal period. The faster decline in these “post-neonatal” causes over the last 15 years has resulted in preterm birth complications now being the leading cause of under 5 deaths in 2017.

I first got involved in the analysis of global child causes of death under age 5 in 2001, when the WHO Child Health Epidemiology Reference Group (CHERG) was formed. Members of the CHERG collaborated with WHO staff to publish global, regional and country-level estimates of neonatal and 1-59 month deaths, which were updated a number of times over subsequent years with continuing improvements in modelling and results. From 2012 onwards, the CHERG and WHO moved to the regular publication of time series of child causes of deaths from 2000 to latest year.  About five years ago, former CHERG members received funding from the Bill and Melinda Gates Foundation to continue collaborative work with WHO as the Maternal and Child Epidemiology Estimates Group (MCEE).

The methods developed by CHERG and MCEE involve the simultaneous estimation of a set of linked regression models for 15 causes of child deaths, in such a way that the estimated cause fractions are constrained to sum to 1. These fractions are then applied to the all-cause “envelopes” of child deaths to generate numbers of deaths by cause over time.

For around 76 countries with high-quality vital registration (VR) data, cause distributions are estimated directly from the death registration data. For another 37 countries with low child mortality, cause of death distributions are predicted from a regression fit to data from countries with high-quality VR data. For higher mortality countries without high-quality VR data, cause of death distributions are predicted from a regression fit to data assembled from studies of causes of death in high-mortality countries, which typically rely on verbal autopsy. These approaches are augmented by WHO and UN program estimates for certain diseases, such as HIV and measles.

Deaths due to malaria are estimated from the high-mortality regression model for African countries in the endemic malaria regions, and for other countries in Africa and the rest of the world from health system and survey data. MCEE works closely with the WHO Global Malaria Program to prepare the malaria mortality estimates for children under 5 and the results are also reported in the World Malaria Report 2018 (https://www.who.int/malaria/publications/world-malaria-report-2018/en/). For countries in the African Region where malaria comprises 5% or more of all deaths in children under 5, child malaria deaths were estimated using a verbal autopsy multi-cause model. This model includes malaria parasite prevalence (PfPR) as a covariate at study level for the data observations and uses national average PfPR for the country-level output estimates. The estimates of PfPR are made by the Malaria Atlas Project at Oxford University (https://map.ox.ac.uk/) using a geostatistical model that incorporates changes in coverage of malaria interventions (insecticide treated bed nets, indoor residual spraying, antimalarial treatment) over time to produce a risk map of parasite prevalence for each year

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Seven WHO staff named in world’s most highly cited list

Seven staff from the World Health Organization have been included in the 2018 Clarivate Analytics 2018 Highly Cited Researchers List. This list includes more than 4,000 leading researchers in 21 fields of the sciences and social sciences from around the world, including 17 Nobel laureates.

Now in its fifth edition, the list identifies influential researchers who have demonstrated significant influence on the research community through publication of multiple highly cited papers. The Web of Science is used as the basis for identifying researchers whose citation records position them in the top 1 percent by citations for their field over the last ten years.

Five of the WHO staff included in the list this year worked at the WHO Headquarters in Geneva:  Mercedes de Onis, Chris Dye, Colin Mathers, Susan Norris, and Gretchen Stevens. The other two, Freddie Bray and Jacques Ferlay work at the International Agency for Research on Cancer (IARC), WHO’s specialized cancer agency based in Lyon, France. Chris Dye, Gretchen Stevens and myself all left WHO earlier this year.

A new cross-field category was added this year to recognize researchers with substantial influence in several fields but who do not have enough highly cited papers in any one field to be chosen. Two of the WHO staff included this year were named in the cross-field category: Gretchen Stevens and Chris Dye.

In my work on global health statistics and burden of disease, I have collaborated widely with academics across the world, and also worked with many of them on WHO expert committees. Twenty-five of these academic collaborators are also included in the 2018 list of the world’s highly cited researchers, including leading researchers from Harvard University, University of Edinburgh, Imperial College London, the London School of Hygiene and Tropical Medicine, the Universities of NSW and Melbourne, the University of Toronto, and the University of Washington.

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NEW PROJECTIONS OF MORTALITY AND CAUSES OF DEATH TO YEAR 2060

Back in 2006, I published a paper in PLoS Medicine with detailed projections of deaths by age, sex and cause for all regions of the world, from year 2002 to 2030 (https://journals.plos.org/plosmedicine/article?id=10.1371/journal.pmed.0030442).  That paper has proved very popular, with over 9000 citations to date.  I’ve updated these projections to most recent WHO baseline estimates several times, and following the release of the latest update of causes of death for year 2016 by WHO earlier this year (http://www.who.int/healthinfo/global_burden_disease/estimates/en/), I have done another update, extending the projections for the first time beyond 2030 to 2060.

This has now been released by WHO on its website at http://www.who.int/healthinfo/global_burden_disease/projections/en/ where regional and global projections can be downloaded in spreadsheet form, along with a methods note. Apart from synchronising the new projections with the 2016 cause of death estimates, the cause-specific trends in the near term are synchronized with estimated recent trends over the last 10 to 15 years. In the longer term, broad trends are largely driven by projection equations which model the epidemiological transition from infectious to non-communicable diseases in terms of projections of average income per capita, average years of education, time, and for some causes also projections of smoking impact.

In the original projections, separate projection models were developed for HIV/AIDS, tuberculosis, lung cancer, diabetes mellitus and chronic respiratory diseases.  These models were revised and updated for this latest update. Additional special projection models were also been developed for malaria, maternal deaths, road injury, homicide, natural disasters and war and conflict.

At the global level, age-standardized death rates for most important causes are falling with time, faster in most cases for infectious, maternal and perinatal causes than for non-communicable diseases (see figures below). The main exceptions are for diabetes, breast cancer and road injuries. The specific projection model for diabetes is based on projections of the prevalence of overweight and obesity and that for road injury is based on projections of vehicles per capita with continued economic development.

IHD = Ischaemic heart disease, COPD = Chronic Obstructive Pulmonary Disease,
ARI = Acute respiratory infection (mainly pneumonia), TB = tuberculosis

However, for many of these causes, the total projected deaths are rising with time because of population growth and ageing. Only the relatively fast declining infectious, maternal and perinatal causes are likely to also have declining total numbers of deaths (see the following two figures).

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Are countries on track to meet the global targets for noncommunicable diseases?

More than half of all countries are predicted to fail to reach the UN target to reduce premature deaths from cancers, cardiovascular disease, chronic respiratory disease, and diabetes by 2030, according to a new analysis published by the NCD Countdown 2030 collaborators in The Lancet ahead of the third UN High-Level Meeting on NCDs commencing on 27 September 2018. WHO is a member of the Countdown 2030 and the paper makes use of the most recent WHO estimates for causes of death released by my Unit earlier this year.

Cancers, cardiovascular diseases, chronic respiratory diseases, and diabetes were responsible for 12.5 million deaths among people aged 30-70 years worldwide in 2016. The following figure from the paper shows the of dying between ages 30 and 70 from these four non-communicable disease groups (referred to below as NCD4) for men and women.

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Noncommunicable disease mortality in tropical countries

The recent WHO update of causes of death for 186 countries in 2016 (www.who.int/evidence/bod) has been used as the basis for an assessment of the importance of non-communicable diseases (NCDs) in tropical countries. The paper “Acting on non-communicable diseases in low- and middle-income tropical countries” was published last week in Nature journal (Ezzati, Pearson-Stuttard, Bennett & Mathers, Nature https://doi.org/10.1038/s41586-018-0306-9). The paper showed that most NCDs cause more deaths at every age in low- and middle-income tropical countries than in high-income Western countries.

The following graph from the paper compares NCD mortality in low- and middle-income tropical countries with that in high-income Western countries. The map (a) shows the share of deaths from NCDs, and map (b) shows the age-standardized death rates from NCDs.  The latter provides a standard measure of the risk of death from NCDs, which removes the effect of different population age structures.  It is clear that NCD mortality risks are higher in most tropical low- and middle-income countries than high income countries.  In contrast, the NCD share of deaths is higher in high income countries, because infectious disease death rates are much lower.

The paper goes on to examine the causes of NCDs in low- and middle-income countries, which  include poor nutrition and living environment, infections, insufficient taxation and regulation of tobacco and alcohol, and under-resourced and inaccessible healthcare. The paper also identifies a comprehensive set of actions across health, social, economic and environmental sectors that could confront NCDs in low- and middle-income tropical countries and reduce global health inequalities.

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Latest information on the state of the world’s health released by WHO

In mid-May, WHO released World Health Statistics 2018: Monitoring health for the SDGs  (WHS2018). This WHO flagship publication compiles data from the organization’s 194 Member States on 36 health-related Sustainable Development Goals (SDG) indicators, providing a snapshot of both gains and threats to the health of the world’s people. While the quality of health data has improved significantly in recent years, many countries still do not routinely collect high-quality data to monitor more than 50 health-related SDG indicators. Nine of the SDG health indicators reported in the WHS2018 are mortality indicators drawn from the latest update of the WHO Global Health Estimates released in April this year.

This update of estimates of death by cause, age and sex for years 2000 to 2016 for 187 countries and for 236 causes and cause groups is available at www.who.int/evidence/bod.  Finalizing this update was a major focus of my work during my last months at WHO before retirement, and indeed, I continued to do some work after retirement to finalize numbers and documentation. So the 2018 World Health Statistics will be the last to which I have made substantial contributions. I have to recognize the huge efforts by my former team to produce and publish this report, in particular Annet Mahanani who was the overall project manager and editor, and Gretchen Stevens who played an important role both in the update of the Global Health Estimates and in the preparation of material and text for the WHS2018.

Since 2016 the World Health Statistics series has served as WHO’s annual report on the health-related Sustainable Development Goals (SDGs) and the 2018 report includes a section summarizing the current status of the health SDGs.

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Disease Control Priorities, Edition 3

The third edition of Disease Control Priorities was launched by the WHO Director General, Dr Tedros Adhanom, in London earlier this month. These nine volumes provide up-to-date evidence on priorities that countries should consider in order to reach Universal Health Coverage. The 9th and last volume includes a chapter from my team that summarizes global and regional patterns of causes of death for 2015 and trends for 2000–15 (chapter-deaths-cause-2000-and-2015). Further information available on the DCP3 website at http://dcp-3.org/

Launch of the DCP3 nine volumes in London on 6th December. At this end of the front row is Dr Ala Alwan, former WHO Regional Director for the Eastern Mediterranean Region and next to him is the new Director General of WHO, Dr Tedros Adhanom.

The chapter colleagues and I contributed to Volume 9 summarizes global and regional patterns of causes of death for 2015 and trends for 2000–15 using the 2015 Global Health Estimates (GHE 2015) released by WHO in early 2017. This period marks the end point for the Millennium Development Goals (MDG) and the starting point for the Sustainable Development Goals (SDGs) for the year 2030. This chapter documents major changes during the MDG era. Progress toward the MDGs, on the whole, has been remarkable, including, for instance, poverty reduction, improved education, and increased access to safe drinking water. Progress on the three health goals and targets has also been considerable. Globally, the HIV/AIDS, tuberculosis, and malaria epidemics have been “turned around,” and child mortality and maternal mortality have decreased greatly (53 percent and 44 percent, respectively, since 1990), despite falling short of the MDG targets. Large reductions in mortality have occurred in Sub-Saharan Africa since the early 2000s, coinciding with increased coverage of HIV/AIDS treatment, methods of malaria control, and scale-up of vaccination coverage. Despite this progress, major challenges remain in achieving further progress on child and maternal mortality and on infectious diseases such as HIV/AIDS, tuberculosis, malaria, neglected tropical diseases, and hepatitis.

The rate of increase in life expectancy in LICs over the past 15 years has exceeded the rate of growth observed for life expectancy in the countries with the highest life expectancies. Longer life expectancies and population aging have resulted in an increased focus on NCDs and their risk factors in LMICs and in HICs. Three-quarters of NCD-related deaths occurred in LMICs in 2015.

The SDGs expand the focus of health targets from the unfinished Millennium Development Goals (MDG) agenda for child and maternal mortality and priority infectious diseases to a broader agenda including noncommunicable diseases (NCDs), injuries, health emergencies, and health risk factors as well as a strong focus on universal health care. The GHE 2015 estimates of trends and levels of mortality by cause will contribute to WHO and UN monitoring and reporting of progress toward the SDG health goals and targets.

Overall, the nine volumes identify 21 essential packages of health interventions across five delivery platforms (population based, community level, health centre, first-level hospital, and referral hospital). DCP3 defines essential universal health coverage in terms of 218 cost-effective interventions that provides a starting point for country-specific analysis of priorities. In the Foreword to Volume 9, Bill and Melinda Gates describe DCP3 as innovately addressing the different needs of countries at different stages in the development of their health systems. DCP3 maps out pathways—essential packages of related, cost-effective interventions—that countries can follow to accelerate progress toward universal health coverage.

Dean Jamison

The Disease Control Priorities projects provide fitting book-ends to my career in international health statistics.  The first Disease Control Priorities project stimulated the original Global Burden of Disease Study for the year 1990 at a time when I was just getting involved in the international work on healthy life expectancy and summary measures of population health. I was experimenting with a form of disability-adjusted life years when the World Development Report 1993, edited by Dean Jamison, published the first global and regional DALY results. I applied the DALY and burden of disease methodology to Australian data to produce the first Australian Burden of Disease study in 1996 and a few years later moved to the World Health Organization to work on updating the Global Burden of Disease Study  with Chris Murray and Alan Lopez.  I joined Dean Jamison, Alan Lopez, Chris Murray and Majid Ezzati in producing the second volume of the Disease Control Priorities (Edition 2): Global Burden of Disease and Risk Factors in 2006.  And now with the third edition, I have contributed another chapter on the latest WHO assessment of global and regional causes of death in 2015, the end of the MDG period and the start of the SDG period.

The nine volumes of DCP3

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