Every year, million 6 million people worldwide die of stroke, but only 300,000 die of meningitis. Consequently, writes Jeremy N. Smith in the New York Times, you might consider stroke to be 20 times worse for humanity than meningitis.
But that’s not necessarily the case, says Smith, who has written a book about efforts to quantify disease and death. People who die of stroke tend to be elderly, while people who die of meningitis are often infants—a distinction that doesn’t show up in a simple count of lives lost to each disease. Further, a simple counting of deaths won’t at all account for the suffering caused by nonfatal conditions.
Consequently, Smith writes, health economists have developed a new metric of health called disability-adjusted life years, or DALYs. DALYs account not only to years lost to an early death but also to how much a nonfatal condition (such as chronic lower back pain) detracts from perfect health.
Smith explains how it works. “Say, for example, that I am in a paralyzing car crash at age 35, but survive until age 65, when I die (alas) of a heart attack,” he writes. “Then, assuming an ideal lifespan of 85 years, I lost 20 years of potential life to the heart attack. But, because I lived 30 years with paralysis after the car crash, the crash cost me 15 years of healthy life. My total health loss is 35 DALYs….”
The DALYs metric can help better allocate healthcare funds among diseases ranging from cancer to lower back pain. Referring to the analytical evidenced-based sabermetric approach to baseball, Smith writes, “Now people everywhere can bring ‘Moneyball’ to medicine.”
