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.

Making sense of the often complex available data on health indicators can be highly challenging. Health data derived from health information systems, including health-facility records, surveys or vital statistics, may not be representative of the entire population of a country and in some cases may not even be accurate. Comparisons between populations or over time can also be complicated by differences in data definitions and/or measurement methods. Although some countries may have multiple sources of data for the same year, it is more usual for data not to be available for every population or year. For example, measurement frequency for data collected through household surveys is typically every 3–5 years. This means that the years for which data are available differ by country. To overcome these and other issues and allow for comparisons to be made across countries and over time, WHO and collaborators have developed mathematical and statistical models with the aim of producing unbiased estimates that are representative and comparable.

As well as reporting on SDG health indicators, the WHS2018 includes several stories focusing on particular topics. One of these is the coverage of essential health services (which was discussed in an earlier blog entry on Universal Health Coverage) and a story on the rising tide of obesity in the young.

The world has seen a more than ten-fold increase in the number of obese children and adolescents aged 5¬19 years in the past four decades ¬ from just 11 million in 1975 to 124 million in 2016. An additional 213 million were overweight in 2016 but fell below the threshold for obesity. Taken together this means that in 2016 almost 340 million children and adolescents aged 5-19 years – or almost one in every five (18.4%) – were overweight or obese globally.

Analysis of these trends has shown that although population growth has played a role in the increase in numbers of obese children and adolescents, the primary driver has been an increase in the prevalence of obesity. Globally, the prevalence of obesity among children and adolescents aged 5-19 years increased from 0.8% in 1975 to 6.8% in 2016. Although high-income countries continue to have the highest prevalence, the rate at which obesity among children and adolescents aged 5-19 years is increasing is much faster in LMIC (see the following figure).

One of the six core functions of WHO is monitoring of the health situation, trends and determinants in the world. Over the years that I have worked for WHO (2000-2018) it has cooperated closely with other UN partner agencies like UNICEF, UNAIDS, UNFPA and the UN Population Division to collect and compile global health statistics. There are a number of established UN multi-agency expert group mechanisms for  cross cutting topics such as child mortality (the UN-IGME including UNICEF/WHO/UN Population Division/World Bank), and specific diseases such as HIV/AIDS (UNAIDS Reference Group), maternal mortality (MMEIG including WHO/UNICEF/UNFPA/World Bank), tuberculosis (WHO STAG), malaria (Malaria Reference Group and Roll Back Malaria- Malaria Monitoring and Evaluation Reference Group). Additionally, WHO collaborates with a network of academics (MCEE) to estimate child causes of death. This collaboration succeeds the former Child Health Epidemiology Reference Group (CHERG) of WHO and UNICEF.

Something that has been immensely satisfying to me over the last two decades is the efforts from all the UN agencies involved in health statistics, as well as the World Bank, and some academic collaborators, to work towards consistent and coherent health statistics used by all the UN agencies and based in a common demographic statistical framework of births, population numbers and deaths prepared by the UN Population Division in their biennial World Population Prospects datasets. When I started working for WHO in 2000, the UN Population Division, the World Bank, UNICEF and WHO all independently produced statistics for child mortality which were not entirely consistent. This was just one example of the lack of coherence across agencies, which has been drastically reduced during the time I have been involved with UN statistics.