Most analyses of mortality focus on how many deaths result from each cause. But this approach offers an incomplete picture of the impact of diseases on patients, society and the medical system. To better understand disease burden, two Cleveland Clinic Medicine Institute researchers conducted a study of causes of death and life-years lost. It appears in the American Journal of Public Health.
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The researchers analyzed data for two years ― 1995 and 2015 ― to identify trends over two decades on the impact of causes of death. They obtained cause-of-death data from the National Vital Statistics System and defined life-years lost based on United States life expectancy for an individual’s age, sex and race.
For all leading causes of death, they calculated and then compared the number of life-years lost to the number of deaths by age, sex and race. “Life-years lost deepens understanding of the impact of premature death and provides additional context for trends in different populations,” says Glen B. Taksler, PhD, study lead author and Associate Staff at Cleveland Clinic’s Medicine Institute.
Key findings include:
- Heart disease is still the number one cause of death, exceeding cancer by six percent, but because it mainly affects the elderly, it results in 23 percent fewer life-years lost. Advances in primary and secondary preventive treatments for atherosclerotic coronary artery disease and blood pressure control in addition to better treatments for acute conditions, such as stents, have led to a 42 percent reduction in years lost to acute myocardial infarction since 1995. However, the prevention of deaths from acute events has led to a rise in chronic cardiac conditions such as heart failure. Treatments for these conditions, such as implantable cardiac defibrillators, have been less effective in extending life.
- Cancer has seen an increase of 16 percent in life-years lost due mainly to population growth and longer life expectancy, which offset gains in disease-specific mortality rates. Six types of cancer ― lymphoma, breast, prostate, stomach and cervical ― had declines in life-years lost while pancreatic and liver cancers had significant increases in life-years lost.
- Life-years lost due to “nondiseases” such as substance use and suicide increased more than all other causes of death. All the gains of the past 20 years in preventing and treating HIV were offset by the increase in accidental deaths.
- Causes of death have changed in elders 80 years and older: Changes in mortality rates for heart disease and Alzheimer’s disease resulted in an increase in life-years lost that exceeded all other causes of death. Alzheimer’s in particular had a three-fold increase in life-years lost. “As we develop new technologies and treatments for some conditions, such as heart disease, we can see the rise of other conditions, such as Alzheimer’s disease,” says Dr. Taksler.
- Racial disparities in health outcomes persist: While life expectancy is increasing for some Black Americans, others, particularly the poor, are more likely to suffer early cardiovascular disease. Blacks are 50 percent more likely to die early from heart disease or stroke and also have higher rates of HIV and infant mortality. Black males are also far more likely to die violent deaths.
Public health and research implications
Based on the study’s findings, “we would expect public policy to focus more on prevention and treatment of chronic heart conditions, addiction, cancers with the highest mortality rates, and neurodegenerative diseases that affect the elderly, such as Alzheimer’s and dementia,” says Dr. Taksler.
Dr. Taksler and study co-author Michael Rothberg, MD, are investigating how addressing risk factors such as high blood pressure and smoking can prevent premature deaths and reduce life-years lost.