GENEVA, SWITZERLAND —What is the best way to estimate how many people suffer from tuberculosis, from the forests of Central Africa to the highlands of Peru? At a 2-day meeting organized and hosted by the World Heath Organization (WHO) here, 60 leaders in the field of global health statistics drew up a set of proposals to improve the world's ability to count the sick and the dead. They called for helping countries to collect better information on disease and death and pledged to work together to produce the best estimates from the sparse data sometimes available.
Knowing how many people in which areas suffer from which maladies is crucial for designing effective public health policies. But there's a problem. In areas that have some of the most urgent public health needs, no one is keeping adequate statistics. In many places, there are no records of either births or deaths. "Where disease burden is greatest, our capacity to measure trends doesn't exist," said Margaret Chan, director-general of WHO, at the start of the meeting yesterday. And even in places with sophisticated health systems, cause-of-death records are often misleading or incorrect. In the United Kingdom, 17% of the deaths are recorded incorrectly, said Christopher Murray, head of the Institute for Health Metrics and Evaluation (IHME) at the University of Washington, Seattle.
Scientists use the available data and complex computer modeling to fill in the gaps and estimate the burden of, say, turberculosis in Peru or high blood pressure in Italy. In the biggest effort ever undertaken, a group of scientists in December published the Global Burden of Disease (GBD) 2010 study, which estimated disease burdens—death as well as years of life affected by disability—for 291 diseases and injuries in 20 age groups in 21 global regions. On 5 March, the study, which Murray coordinates, will publish its country estimates for the same set of diseases. (They will also announce plans to launch a Global Burden of Disease 2.0, which will be updated annually—or even more frequently.)
But the computer models that they and others use have become so complex that it is difficult for outsiders to test and validate the estimates. "We are in a time of big data," said Peter Piot, director of the London School of Hygiene & Tropical Medicine, who co-chaired the meeting. The ENCODE project that tries to make sense of the flood of human genetic information and the CERN high-energy physics lab are examples, he told the meeting, "and the global burden of disease is in that category. In science we strive for independent confirmation, but like the physics discoveries at CERN, it is hard to independently verify the results because no one has the resources to do so."
In the last few years, debates over differences between estimates from different groups have become increasingly heated. WHO's estimates of maternal mortality, for example, were higher than those that the IHME published in 2010. And in 2012, IHME's estimates of adult malaria deaths in sub-Saharan Africa were dramatically higher than WHO's numbers. Tensions between the different modeling groups grew so much that WHO, which had originally collaborated on the GBD 2010 study, did not allow any of its staffers to be listed as authors on the papers published in December.
In an effort to diffuse some of those tensions, the Bill & Melinda Gates Foundation, which supports IHME, funded WHO to organize the meeting. The effort seems to have been successful. The participants agreed that gaps between estimates derived by different groups can sometimes be an advantage. "The challenge of the different numbers can lead to improvement in the science," says Colin Mathers of WHO's department of health statistics and information systems. They drafted a set of proposals, which WHO is expected to publish next week, that calls on the global health community to invest in better data-collecting efforts on the ground, something that everyone agrees is desperately needed. Those responsible for health statistics in low- and medium-income countries "are often found in the darkest, farthest corners of the health ministry," where they get little attention and even less money, said Henk Bekedam, director of health sector development at WHO's Western Pacific Region in Manila.
The participants also agreed to try to better explain their work to each other and to the wider public health community by, for instance, sharing data sets and specialized software as much as possible. The group also proposed developing ways to encourage regular communication between researchers working in the area.
One problem, several participants lamented, is that global health funding agencies prefer to spend limited resources on "sexier" efforts such as vaccination campaigns and treatment efforts than health statistics. That perception should change, said meeting co-chair Hans Rosling of the Karolinska Institute in Stockholm, whose Gapminder Foundation develops popular graphics that often reveal surprising patterns in health and population data. "You do enormously important work," he told the meeting at the close. "And on Valentine's Day, I am happy to tell you: What you do is very sexy."
