Turning to Big, Big Data to See What Ails the World

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Like many fields, public health is in the midst of a data revolution: randomized control trials, pay-for-performance and value calculations, all based on data, are changing our ideas about what works and how to finance it.

The impact of these new methods to gather and evaluate data pales, however, next to the Global Burden of Disease Report, an attempt to understand what sickens us and kills us in every country in the world. The Global Burden of Disease study is a single scientific project on a scale with the moon landing or mapping the human genome. It has been going for a quarter century and involves hundreds, perhaps thousands, of scientists. In 2012, its most recent report, based on 2010 data, became the subject of the first issue that the medical journal The Lancet devoted to a single study.

This is big, big, big data.   And it’s had an enormous impact.

In a new book, “Epic Measures: One Doctor, Seven Billion Patients,” the journalist Jeremy N. Smith profiles the Global Burden of Disease report and the impatient genius behind it. The doctor is Christopher Murray. In 1973, Murray’s parents, a cardiologist and a microbiologist, shipped a generator, cardiograph machine, microscope and two weeks’ worth of medical supplies from Minnesota to England, bought two Land Rovers, and ferried and drove to Niger, crossing the Sahara roadless and alone with their three children. There they ran a hospital for a year by themselves. Later, the family would go back to Africa every summer to run medical clinics.

“Epic Measures” is a biography of Murray and his attempt to diagnose the world. For a book about compiling data, it’s remarkably entertaining. But it also reveals the importance of data in its least glamorous form. The researchers in the Global Burden study got their information by combing through birth and death records and hospital files and doing household surveys. They found such arcane bits of data as per-capita lunch meat consumption in Bulgaria, figures for four different kinds of liver cancer in Tanzania, and information on eating disorders, nonvenomous animal bites and acne. Put together, this data allows policymakers to make better use of their scarce health resources by spending them on what’s most important.

Murray, along with his colleague Alan Lopez, published the first Global Burden of Disease report at the World Bank in 1993, using data from 1990. In 1998, Murray and Lopez moved to the World Health Organization. The W.H.O. traditionally publishes whatever health data governments supply. The second Global Burden study, called the 2000 World Health Report, changed that — and many countries didn’t like it.

Most controversial was a single table ranking countries’ health system performance. (The United States placed 37th overall — behind Chile, Colombia, Costa Rica, Oman, and Morocco. America was first in spending, though.)   Countries ranked near the bottom of the pack objected. A delegation from North Korea protested because the report looked at disease burdens as well as deaths. “Nobody is sick in North Korea,” they argued.

The report was bound to antagonize, but Murray didn’t help. He “seemed to operate under the assumption that scientific progress relies on picking fights,” Smith writes. Perhaps true, but it was not the way to win political allies.   In 2003 the W.H.O. got a new leader, who disbanded Murray’s group.

Several years in the wilderness (if one can call Harvard the wilderness) followed, and then Bill Gates called. From the beginning of his foundation’s public health work, Gates had been drawn to Murray’s approach. The first Global Burden report was one of the first books Gates read on the subject. He learned that diseases he’d never heard of were killing hundreds of thousands of children annually — and were preventable for a few dollars a year. That report essentially set him on his journey.

Gates brought Murray to Seattle, and established the Institute for Health Metrics and Evaluation at the University of Washington, with funding from the state as well.   (I have never met Murray, but the Solutions Journalism Network — which David Bornstein and I co-founded — collaborates with the I.H.M.E. to help journalists use the organization’s data in articles about what works in health.) The first three Global Burden of Disease reports came out every 10 years. Now they are updated regularly. Visualizations of all this data are published on the G.B.D. Compare website.

Aside from its sheer comprehensiveness, the Global Burden study was innovative because it offered a new way to measure health: not just what people die of, but what makes us sick. If you count only deaths per population, people are indistinguishable whether they died at age 95 or 2. If you only look at life span, everyone who died at 75 looks the same, whether they led healthy lives or not.

Murray decided he needed to measure years of healthy life lost. This had two parts. One was measuring how much a life was cut short by death. That weighted a child’s death as much worse than the death of an elderly person.

More controversially, Murray decided to measure disability: What makes people sick without killing them? That involved looking at the prevalence of different diseases and also at the harm each causes. The Global Burden of Disease study devised a method for comparing the impact of various diseases and conditions.

We have a way to compare the value of disparate goods and services — it’s called money.   To compare suffering, Murray and his colleagues came up with a measure they put into the 1993 report: years lost to disability. They placed a value on each kind of health loss: chronic low back pain, was weighted as 0.366, which means that someone who lived with this problem lost 3.66 years of health life each decade.    Severe depression, by contrast, was weighted at 0.655— six and a half years lost each decade.

These measures, obviously, were highly controversial.   Not everyone would agree, for example, that urinary incontinence is more than 10 times more debilitating than a thumb amputation. Other controversies surround the Global Burden of Disease Report’s confident use of data that no one can be confident about: How, exactly do we track urinary incontinence in countries that have trouble keeping death records? How do we measure problems like domestic violence anywhere? G.B.D. staff answer that they do the best they can, and it’s better than the highly political or arbitrary numbers used previously — many countries didn’t actually record birth or death data, and just made it up. But the information about the figures’ range of uncertainty can easily get lost, giving an exaggerated impression of certainty.

Governments and international organizations want to invest their scarce resources into fighting the most important causes of health loss. But Global Burden of Disease data showed that policymakers were often very wrong about what those causes were.

For example, at the W.H.O. in 1990, well over 90 percent of staffing and resources went to the usual-suspect poor-country issues: communicable diseases, pregnancy, childbirth and early childhood death.   But these accounted for less than half of world health loss. Injuries, by contrast, caused 12 percent of health loss — and had just a single W.H.O. staff member, Smith writes.

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Read previous contributions to this series.

In 1990, the most important causes of years of life lost in developing countries were child underweight, household air pollution and suboptimal breastfeeding.   But in the last 20 years, we have made previously unimaginable progress in bringing down child and maternal deaths. The leading risk factors for years of life lost now in poor countries are the same as in rich ones:  dietary risks, high blood pressure and smoking.  The first divergence comes with 4th place:  in rich countries it’s alcohol use. In poor ones, it’s — well, is it household air pollution from cooking with wood or charcoal indoors, or is it dirty drinking water?  The answer is in the quiz below. (In much of Latin America, the leading cause of years of life lost is interpersonal violence. That’s progress, of a sort.)

The disconnect between what we think causes the most suffering and what actually does persists today. It is partly a function of success. Diarrhea, pneumonia and childbirth deaths have greatly declined, and deaths from malaria and AIDS have fallen, although far less dramatically. (The charts here show the stunning improvement in health around the world. And here are similar charts tracking progress in hunger, poverty and violence — a big picture that’s an important counterpoint to the constant barrage of negative world news.) This success is partly due to changes made because of the first Global Burden reports.

The downside is that longer lives mean people are living long enough to develop diabetes and Alzheimer’s.   “What decline we’re seeing from communicable diseases, we’re seeing a compensatory increase from diabetes,” Murray said.   And neurological diseases such as Alzheimer’s now account for twice as many years lived with disability as cardiovascular and circulatory diseases together, Smith writes.

This is not simply because people are living longer. It’s also a function of worsening diet everywhere, as poor societies adopt the processed foods found in rich ones.

The most surprising information, though, came not in measuring deaths, but disability. “Major depression caused more total health loss in 2010 than tuberculosis,” Smith writes. Neck pain caused more health loss than any kind of cancer, and ostearthritis caused more than natural disasters. For other findings that may surprise you, see the quiz.

The report is a giant compilation of “who knew?”

Based on this information, countries and international organizations have been able to change how they spend their health resources, and some ambitious countries have done their own national Burden of Disease studies.

Iran, writes Smith, found that traffic injury was its leading preventable cause of health loss in 2003, and put money into building new roads and retraining police. It also targeted two other big problems its study found: suicide and heart disease.

Australia, responding to the high impact of depression, began offering cost-free short-term depression therapy .

Mexico was one of the countries making the most use of Global Burden of Disease data, after Julio Frenk became health minister in 2000.   Frenk had been Murray’s boss at the W.H.O., and a participant in Murray’s work. He found that Mexico’s health system was targeting the communicable diseases that predominated in 1950, not what currently ailed Mexicans. In response, Frenk established universal health insurance (before that, 50 million were uninsured) and set coverage according to the burden of disease.

The program covered emergency care for car accidents, treatment of mental illness, cataracts, and breast and cervical cancer — all of which had been uncovered, even for people with insurance. “You want to cover those interactions that give you the highest gain,” ]he said.

Murray and company have now branched out beyond diagnosis to measuring treatment: How many people really have access to programs like anti-malaria bed nets or contraception? How much is being spent and what does it buy? Where are the most useful points of intervention?   Meanwhile, data from the Global Burden reports  is seeping further into health policy decisions around the world — data that saves suffering and money and lives.