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Study reveals trends in US death rate, leading causes of death over 30 years

September 14, 2005

The death rate from all causes of death combined decreased by 32 percent between 1970 and 2002, with the largest decreases for heart disease and stroke, but with an increase in death rates for diabetes and COPD, according to an article in the September 14 issue of JAMA.

Age-standardized death rates from all causes have decreased in the United States since the 1960s; however, the overall trend masks substantial variations in cause-specific rates and in the number of deaths occurring in different age groups from specific conditions, according to background information in the article. Understanding these trends and the relationship between the age-standardized death rates and the actual number of deaths that occur could provide valuable insight into the forces that shape the nation's health.

Ahmedin Jemal, D.V.M., Ph.D., of the American Cancer Society, Atlanta, and colleagues examined trends in death rates and number of deaths from the six leading causes in the United States and considered the relationship of these trends to disease prevention and health care in an aging population. The researchers analyzed vital statistics data on death in the United States from 1970 to 2002 from each of the 6 leading causes of death: heart disease, stroke, cancer, chronic obstructive pulmonary disease (COPD), accidents (i.e., related to transportation [motor vehicle, other land vehicles, and water, air, and space] and not related to transportation [falls, fire, and accidental poisoning]), and diabetes mellitus.

The researchers found that the age-standardized death rate (per 100,000 per year) from all causes combined decreased from 1,242 in 1970 to 845 in 2002 (32 percent decrease). The largest percentage decreases were in death rates from stroke (63 percent), heart disease (52 percent), and accidents (41 percent). The largest absolute decreases in death rates were from heart disease (262 deaths per 100,000), stroke (96 deaths per 100,000), and accidents (26 deaths per 100,000).

The death rate from all types of cancer combined increased between 1970 and 1990 and then decreased through 2002, yielding a net decline of 2.7 percent. In contrast, death rates doubled from chronic obstructive pulmonary disease over the entire time interval and increased by 45 percent from diabetes since 1987. Despite decreases in age-standardized death rates from 4 of the 6 leading causes of death, the absolute number of deaths from these conditions continues to increase, although these deaths occur at older ages.

" the number of deaths continues to increase because of population growth and aging. It is the number of individuals affected by various conditions rather than the age-standardized rate that influence the planning and allocation of preventive and medical services," the authors write.

"Several important insights are suggested by these temporal trends in the death rates and number of deaths at various ages. First, the decrease in the age-standardized death rate for 4 of the 6 leading causes of death in the United States represents progress toward one of the fundamental goals of disease prevention by extending the number of years of potentially healthy life. This progress has been greater for cardiovascular disease and for accidental deaths than for cancer, yet even for cancer the age-standardized death rate has been decreasing by 1.1 percent per year since 1993. Less favorable developments are the slowing of the decline in age-standardized mortality rates from stroke and accidents since the early 1990s, and the increase in death rates from COPD and diabetes."

"The reduction in the death rate from accidents from 1970 through the early 1990s coincided with implementation of a 55 mph speed limit during the first energy crisis in the 1970s and mandated use of seat belts in most states beginning in 1984. The recent flattening of the accident mortality rate coincides with the relaxation of the maximum interstate speed limits since 1987. The biphasic [having two phases] trend in cancer mortality rates reflects both the impact of the tobacco epidemic on tobacco-related cancers through 1990, followed by reduction in cancer mortality through tobacco control and advances in early detection, in treatment, or in both. The increase in COPD death rates results largely from the long-term effects of tobacco smoking in an aging population, whereas the increase in diabetes mortality since the late 1980s reflects dramatic increases in obesity," the researchers write.

"A consequence of the large decrease in cardiovascular death rates, combined with high-birth rates that immediately followed World War II, is the growing importance of health and health care needs in an aging population. While improved detection and treatment for chronic diseases has resulted in declining mortality rates, it has also increased the prevalence of 'treated disease' and an associated increase in health care expenditures," the authors conclude.

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