The most significant component of the mortality decline at older ages is the reduction of death rates due to cardiovascular disease (CVD), including both heart disease and stroke. In the United States, heart disease has been the leading cause of death since 1921, and stroke has been the third most common cause since 1938. From 1950 to 1996, age-adjusted death rates for these two causes declined by more than half (by 56% for heart disease and by 70% for stroke). It is estimated that 73% of the decline in total death rates over this time period was due to this reduction in CVD mortality (25).
The exact cause of the decline in CVD mortality is open to debate, although it is surely due to a combination of factors. For the United States, all of the following have been cited as factors contributing to this decline:
1. A decline in cigarette smoking among adults
2. A decrease in mean blood pressure levels
3. Increased control of hypertension through treatment
4. Changes in diet, especially a reduction in the consumption of saturated fat and cholesterol
5. Improvements in medical care, including better diagnosis and treatment of heart disease and stroke
6. The development of effective medications for treatment of hypertension and hypercholesterolemia, and an increase in coronary-care units and emergency medical services for heart disease and stroke (Chapters 3,15, and 16) (25)
The rapid decline in CVD mortality began around 1968 in the United States and other industrialized nations. Given the precipitous nature of this decline, it has been argued that therapeutic interventions were the most important factor, since changes in diet and lifestyle should have led to a more gradual pattern of change (26). It is worth noting that landmark investigations, such as the Framingham Heart Study, began in the late 1940s and began to provide significant breakthroughs in our scientific understanding of CVD during the 1960s (27).
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