Am J Pub Health. 2005;95(1):103-108.
Background
The increase in life expectancy at birth between 1981 and 2000 in England and Wales has been attributed to reductions in coronary heart disease (CHD) mortality rates. This, in turn, has been attributed to the widespread use of effective therapies such as thrombolysis, aspirin, ACE inhibitors, statins, and coronary bypass surgery. However, improvements in cardiac treatments explain less than half of this observed cardiovascular mortality decline. Reductions in major risk factors such as smoking, cholesterol, and blood pressure have also made substantial contributions in increased life expectancy rates.
Objective
The authors aimed to estimate life-years gained from advances in cardiac treatments in comparison to those gained from cardiovascular risk factor changes.
Methods
The IMPACT CHD mortality model was used to estimate the number of deaths prevented or postponed in 2000 that could be attributed to improved cardiac treatments or risk factor changes since 1981. For each treatment category, median survival was obtained from the best available population-based data. The number of life-years gained in 2000 for each treatment category and risk factor change was then estimated as the product of the number of deaths prevented or postponed in 2000 and the age-specific median survival for that age-gender group.
Results
In 2000, there were 68,230 fewer deaths compared with expected mortality rates in 1981. The model used for this study estimated 61,595 fewer deaths, which represents 90% of the observed CHD mortality decline. This mortality decline amounted to 925,415 life-years gained among people aged 25 to 84 years. Specific medical and surgical treatments for patients with CHD resulted in a gain of approximately 194,145 life-years by 2000. The largest contributions came from secondary preventive treatments following a myocardial infarction or coronary revascularization (32%), acute treatment of myocardial infarction (20%), and coronary surgery for angina (13%). On the other hand, risk factor changes in the population between 1981 and 2000 accounted for approximately 731,270 life-years gained, and represented 79% of all life-years gained in 2000. The largest contributions came from reductions in smoking (54%), high blood pressure treatment (28%), and cholesterol lowering (22%).
Discussion
Modern cardiac treatments resulted in substantial gains in life-years between 1981 and 2000. However, relatively modest reductions in major risk factors resulted in more impressive life-year gains that are nearly quadruple to the number seen with CHD treatment. Looking at it in another way, each death avoided or postponed by treating a patient with recognized CHD yielded an average additional 7.5 years of life. In contrast, each death avoided by a risk factor reduction yielded an average additional 20 years of life. Gains for risk factor control would have been even greater were it not for the adverse trends seen in physical activity, obesity, and diabetes. Smoking reduction in particular resulted in substantial life-year gains. Therefore, effective public policies to promote healthy diets and tobacco control may yield substantial additional years of life.
Comment
Although mortality model application is limited by the inherent assumptions needed, the findings in this study are consistent with mortality analyses conducted by other investigators. This study aimed to answer an important question with ramifications on allocation of healthcare resources-pitting primary prevention versus secondary preventive therapies. To get more "bang for your buck," risk factor modification clearly wins out. Unfortunately, society is better driven by reactionary imperatives rather than by vague long-term potential events. A consistent message promoting healthy lifestyle choices is important, not only from healthcare professionals but also from our federal policy makers.