DALY System Forces WHO to Up Their Game

How do we measure health? The answer has changed dramatically over time, most recently with the implementation of the DALY system, and the IHME Global Burden of Disease Study. In the past, health was measured in terms of number of years lived, and number of deaths caused by a specific condition. It is because of the limitations of this data that our measurement of health has improved, even if it is not perfected. Aid organizations such as the World Health Organization (WHO), UNAIDS, and UNICEF had each developed different methods of acquiring data, with minimal fact checking. Even within the same organization, there was not collaboration between committees. This kind of miscommunication has led to an inflation of health data, as well as the double and even triple counting of deaths. For example, children who were malnourished were likely to contract many diseases, such as malaria, pneumonia, or diarrhea. This single death could be counted separately by each team in the WHO, leading to the inflated numbers.

In addition, the sources of health statistics are inconsistent, specifically at the WHO. In attempting to organize data from all 196 countries, many committees accepted self-reported statistics. It is in the best interest of the country to report fewer deaths and diseases than actually occurred, and many send in “adjusted” numbers. Because of the overwhelming workload, this data often becomes incorporated into WHO data, and reported without any modifications. In addition, when data is collected from hospitals, in many cases it is incomplete or even altered. This is often true in cases of suicide, when doctors will record alternate causes of death so as to not interfere with life insurance. Even more often, where there is no medical care, there are no records. In situations like this, deaths and cause of deaths must be estimated using models. This method of measuring health produced inconsistent numbers, and the overall system only accounted for mortality and its causes, with no regard for disability or other factors that lower quality of life.

It is because of inconsistent data between and within organizations that Chris Murray and Alan Lopez began the Global Burden of Disease study to create one comprehensive, unbiased collection of data from every country in the world, by age and sex. The Global Burden of Disease Study revolutionized how we measure health. The IHME tracked the quantitative mortality rates as other organizations had done, but also created a brand new system of measuring the health of a country. The introduction of DALYs, or Disability Adjusted Life Years, accounted for quality of life lost, not just quantity. They first used the current system of Years of Life Lost (YLL) to account for early death. The number of years lived is subtracted from the ideal life span of the country. This value is the potential years of life lost, and weights years lost early in life as more valuable than those lost as an adult.

In addition to this method, Murray and his colleagues created a scale of 0 (perfect health) to 1 (death), and assigned a value to the health conditions suffered world wide. This value was a ratio of life lost per year. For example, deafness was assigned a disability weight of 0.2, meaning that for every year lived, one fifth of it was “lost” to disability. DALYs are calculated by adding years of life lost by early death to the years lost to disability to paint an all-inclusive picture of the what ails the world. The data from this system produced entirely different numbers from those previously published, and it drew a lot of attention to the disparity between aid organizations. Its success has led to the DALY system being accepted and implemented by many other health organizations.

While it is imperative to include nonfatal conditions in analysis, the idea of ranking disability and counting disability as life lost is problematic for many reasons. To begin, assigning a quantitative value to a subjective condition leads to many conflicting ideas and opinions. Every individual who lives with a condition experiences it slightly differently, creating problems assigning the same disability weight to the entire condition.

Even more controversial is the act of agreeing on a universal ranking of disability weights. The Global Burden team polled doctors, the public, and individuals with the condition and came to a consensus. However, the numbers could be skewed by people who have the condition ranking it as less than it is, or people on the outside not really understanding the impact of the condition. While it is clear that having a system that accounts for quality of life is better than one that does not, the DALY system still has flaws and needs improvement.

Chris Murray and the IHME Global Burden of Disease Study have redefined how we look at world health. The creation of new methods validates those suffering with many nonfatal conditions and is a more accurate representation of what ails the world. Through the thousands of hours spent and the statistical improvements made, he has forced other world health organizations to up their game and provide the most accurate data to the public.