Articles

Heart disease: one of science-based medicine’s great successes

Sixty years ago, the world was full of miracles. Western Europe was recovering from the devastation of World War II, an agricultural revolution promised to banish the fear of starvation in large parts of the world, and the mythical Mad Men era gave Americans a taste of technology-dependent peace and prosperity unlike any in the past. Despite the technological progress that would soon send animals into space and return them relatively unharmed, Americans, and westerners in general, were still dying of heart disease at a frightening rate. If you, as a middle aged American, experienced chest pain and were lucky enough to make it to a hospital (about 20% of all sufferers would die immediately), you would probably be given nitroglycerin and morphine to control you pain, put on bed rest, and could expect to live a few more years, with limited physical activity.

Heart disease continues to be a top killer of Americans, but there has been a dramatic decline in heart disease mortality in the last 60 years, with age-specific mortality rates dropping 60%. Fewer people are developing heart disease, and those that have it are living longer. It is estimated that in 2000 alone, there were 341,745 fewer heart disease deaths than would have been expected if rates had remained unchanged.  This decline has not been driven by a renaissance of alternative medicine.  It has been driven by science.

The trend has been going on for many decades, and has been accelerating, although current trends in diabetes and obesity put us at risk for more overall cases of heart disease in the future. So what are we doing right? How have we managed to cut the death rate from heart disease so dramatically?

So-called alternative medicine practitioners seem hell-bent on finding evidence-free ways to prevent and fight disease. No lie is too blatant in the pursuit of their ideology. For example, one chiropractic website claims that everything we think we know about prevention of heart disease is wrong:

The tyical risk factors include high cholesterol, smoking, high blood pressure, and diabetes.  Prescription drugs serve as these programs’ centerpiece, with counseling and education as adjunct treatments.  They are spearheaded by the American Heart Association, the American Medical Association, local and state governments, and even the federal government.

Yet 10 years ago study results by the Cochrane Heart Group and The Cochrane Collaboration (http://www.cochrane.org/) showed that treating risk factors was “ineffective in achieving reductions in total or cardiovascular disease mortality (death).”

Of course, we don’t get a real citation to follow.    One of the most offensive investigations into heart disease prevention is the TACT trial, an unethical trial asking a question that doesn’t require an ethics-free clinical trial to answer.  We know a lot about heart disease.  And we know this because of well-designed trials and studies that ask the right questions.  The medical literature over the last 30 years has seen a flood of studies of heart disease. As would be expected, most are incomplete, answering only one or two questions, and studies often conflict.  But over time, trends emerge, and the truth precipitates from the noise.

In reducing heart disease mortality, there have been different relative contributions from primary prevention (preventing new cases of heart disease) and secondary prevention (preventing recurrent cases).  A recent study in the American Journal of Public Health analysed data from 1980-2000. The authors found that most of the reduction in deaths from heart disease (nearly 80%) were due to primary prevention, specifically decreasing smoking rates, and improvements in blood pressure and cholesterol levels. Society-wide reductions in smoking, blood pressure, and cholesterol are saving hundreds of thousands of lives in the U.S. every year.  This is a different conclusion than that of the Virginia chiropractors who once read an un-citable Cochrane review.

What’s best about these data is they give us guidance;  real science gives us real predictions.  The smoking rate in the US is still hovering around 24%. More than half of people with known high blood pressure do not have their blood pressure under control. Evidence shows us that we can easily prevent more heart attack deaths through education and through better adherence to extant treatment guidelines.  Behavioral changes such as smoking cessation, diet and exercise, and the proper use of medications can all contribute to the fight against heart disease.  Reducing heart disease deaths isn’t all that complicated, and it won’t take miracles. We just have to follow the evidence.

*Similar trends have been seen in other English-speaking countries

References

Hurlburt CW (1927). THE CARDIAC CRIPPLE. Canadian Medical Association journal, 17 (11), 1305-9 PMID: 20316574

Sytkowski PA, Kannel WB, & D’Agostino RB (1990). Changes in risk factors and the decline in mortality from cardiovascular disease. The Framingham Heart Study. The New England journal of medicine, 322 (23), 1635-41 PMID: 2288563

FRY J (1964). CORONARY HEART DISEASE IN GENERAL PRACTICE: NATURAL HISTORY OVER TWELVE YEARS (1950-1961). Proceedings of the Royal Society of Medicine, 57, 39-42 PMID: 14114173

Centers for Disease Control and Prevention (CDC) (1999). Decline in deaths from heart disease and stroke–United States, 1900-1999. MMWR. Morbidity and mortality weekly report, 48 (30), 649-56 PMID: 10488780

Young, F., Capewell, S., Ford, E., & Critchley, J. (2010). Coronary Mortality Declines in the U.S. Between 1980 and 2000 Quantifying the Contributions from Primary and Secondary Prevention American Journal of Preventive Medicine, 39 (3), 228-234 DOI: 10.1016/j.amepre.2010.05.009

Wijeysundera HC, Machado M, Farahati F, Wang X, Witteman W, van der Velde G, Tu JV, Lee DS, Goodman SG, Petrella R, O’Flaherty M, Krahn M, & Capewell S (2010). Association of temporal trends in risk factors and treatment uptake with coronary heart disease mortality, 1994-2005. JAMA : the journal of the American Medical Association, 303 (18), 1841-7 PMID: 20460623

Posted in: Science and Medicine

Leave a Comment (81) ↓