Monday, February 26, 2007

AHA Makes Headlines With Story That's Been in the News for Over Half a Century

The Story:
The number one killer of women in the US is heart disease, and we need to do something about it.

For as far back as I looked (1950), the CDC has records showing that women, and men, have been laying down their lives to cardiovascular disease (CVD).

You can click the chart to the right for a larger version. Or you can see the CDC's whole report here (pdf):

US Age-adjusted Death Rates, 1950-2001

You have to hand it to the American Heart Association (AHA) for pushing such a ho-hum story to the top of the news heap, if only for 2 hours on February 19th. It appeared briefly in the Health segments of news broadcasts and websites and was quickly superseded by the Salmonella-in-Peanut-Butter story and the Pregnant?-Eat-Fish story.

It's hard to care about a somber truth that's been with us day after day, year after year, for most of our recent history. But we would do well to care, not least because heart disease doesn't have to hold such a hallowed place. It is, in fact, preventable. And compared to the cost of dealing with cardiovascular problems once they rear their head, the actions needed for prevention are cheap, doable for most people, and they work.

You may now be asking, what are they?

Here's where the AHA earned their pat on the back. They just published a set of guidelines, not their first, in their peer-reviewed journal Circulation. Boy, did they do they homework.

Evidence-Based Guidelines for Cardiovascular Disease Prevention in Women: 2007 Update

They identified thousands of CVD-pertinent studies (5774 to be exact) that were performed in the brief period between 2003 (the cut-off for their previous guidelines) and 2006. They whittled those down to 246 that had the best research designs, with study populations of at least 1000 - one meaty pile of evidence. They then extracted those studies' findings, ranked them, and whipped up a list of recommendations.

Here's their list:


The guidelines above might be condensed into another unfortunately lackluster message: Eat a healthful diet, exercise, don't smoke. But after raking through their paper, a few points stood out for me ... points that sometimes didn't make it into the news summaries, and sometimes contradicted them when they did:

1. They recommended "a minimum of 30 minutes of moderate-intensity physical activity" daily. They increased this time to 60-90 minutes to achieve or sustain weight loss. However, this increase was not backed by any evidence from their included trials, unlike the 30 minute recommendation. Rather, it was "based on expert opinion, case studies, or standard of care."

It seems intuitive that more would be better in this case. But if I'm going to set aside an hour and a half of my day to exercise, I'd prefer to see this lengthier time withstand more and better scientific scrutiny. Otherwise, one could easily rationalize it away as an example of the law of diminishing returns.

If 60 or 90 minutes/day is really the minimum required to stave off a heart attack, please don't tease me with 30 :)

2. The following was some guidance they gave for the use of aspirin in women. Pay close attention.
"Routine use of aspirin in healthy women <65 is not recommended to prevent MI."
There are three key words in that sentence: "healthy", "women", and "MI" (Myocardial Infarction = heart attack). Replace any one of those three terms, respectively, with "high-risk", "men", or "stroke", and aspirin therapy may be indicated.

We're only beginning to learn how men and women differ in their response to drugs and other therapies. Unfortunately, the bulk of studies upon which we depend for clinical guidance do not make gender distinctions. I intend to address some of these differences in a later post. For now, I'll just note that aspirin was found more useful in protecting women against strokes but not heart attacks, and protecting men against heart attacks but not strokes ... and it's always accompanied by risk of gastrointestinal bleeding.1

3. They recommended that depression be treated.

For as much as omega-3 fatty acids have gained a reputation for lowering CVD risk, the AHA ranked treatment for depression higher, and for good reason:
  • Depression treatment: "Weight of evidence/opinion is in favor of usefulness/efficacy."
  • Omega 3 intake: "Usefulness/efficacy is less well established by evidence/opinion."
There's a complex relationship between depression and heart disease. (The same could be said for depression and other diseases - diabetes is one I'm familiar with in my line of work.) Depression could directly cause, indirectly cause, or result from CVD ... or any combination of the three. Also, depression exerts a range of effects, both physiological (release of stress hormones, activation of sympathetic nervous system - "fight or flight") and behavioral/emotional, which feed into the connections in the previous sentence.

What is known is that depression complicates CVD outcomes, and that the association between the two is more pronounced in women than in men.2 This area of study is hot right now. However, while researchers are teasing this relationship apart, there is every reason (not least of which is quality of life) to treat depression.

4. They recommended women "limit intake of saturated fat to <10% of energy, and if possible <7%."

In my experience, there is an enormous chasm between this kind of recommendation and it's execution. Even if women have knowledge of foods that are high in saturated fat, they can't easily parlay that into knowledge of intake, and even if they have knowledge of intake, they can't easily parlay that into % of energy. To make a recommendation based on % of energy, let alone the distinction between 10% of energy and 7% of energy, however beneficial this distinction has proven in studies, seems pointless. Here's where a Pollanism would have been better: eat less meat and cheese.

5. The AHA expert panel declined from including "yoga/stress reduction" in their guidelines because they "determined the data were insufficient to make clinical recommendations." Another therapy that's been in the spotlight lately is vitamin D supplementation, a topic the AHA discusses readily on their site3 (as does Dr. Davis) but refrained from addressing here, again due to a paucity of research.

So there's more in store. These 2007 Guidelines aren't the be-all and end-all for ways to avoid CVD, but they're chock full of useful advice. And, at least for some people, they make a great conversation piece, as you might attest to if you've read my post this far :)

1 Aspirin for the Primary Prevention of Cardiovascular Events in Women and Men, JAMA, 2006.
2 Depression and Cardiovascular Disease, Circulation, 2005.
Another good resource on depression and heart disease: Depression Can Break Your Heart, National Institute of Mental Health, 2001.
3 Vitamin D Gets an A+ for Treating Heart Disease, AHA, 2002.

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