Improving Self Reported BMI

Many epidemiological studies measure adiposity (obesity) through the surrogate BMI via self reported measures of height and weight. As I have mentioned before, there are many problems with this. But how can we improve on this while maintaining our level of accuracy and not using a direct measure requiring a more intensive doctor visit?

Two ideas to use along with BMI:

1. Waist size - pant size for men, dress size for women

2. Bench press - probably more reasonable for men. Could use max (weight you can bench press once), or weight you can bench press ten times.

How Reliable is Health Advice?

Via the Health Blog:

Just 11% of more than 2,700 established heart recommendations are backed by high-quality testing, says a study in the current issue of JAMA.

The American College of Cardiology and American Heart Association jointly issue guidelines to doctors, WSJ explains. The ones thought to have the highest level of evidence are based on multiple randomized clinical trials. Those considered weakest are backed by expert opinion or case studies.

According to the JAMA paper there are three type of sources:
1. Sources based on multiple randomized clinical trials (high quality testing)
2. Sources based on a single randomized clinical trial or observational study (moderate)
3. Sources based on case studies, expert opinion - etc (poor)

As an epidemiologist, I will probably spend most of my time dealing with observational studies in the moderate category. While not "high quality", these are still important since many randomized control trials can not be conducted because of ethical, feasibility, and financial reasons. For example, we can't ethically conduct a randomized control trial on whether smoking causes lung cancer - since there is substantial evidence that we would inflecting harm in our control arm.

However, randomized clinical trials (RCTs) should be used whenever possible because they are removing many biases and confounding from the relationship of interest. A classic case of the benefit of RCTs is Hormone Replacement Theory (HRT) in women. The Nurses Health Study and others found a protective effect on mortality for HRT in several of their observational studies. Their evidence looked so convincing that hundreds of thousands of women went on the therapy. That was until randomized clinical trial results found that it can increase breast cancer and disease risk.

Getting back to the JAMA article, it's pretty scary when you think about. Heart Disease is America's biggest killer, and quite possibly the most widely studied disease. What this says is that there is a lot of work to do in the health field and that there will be a lot of reversals, ala HRT, of doctor opinion in future recommendations.

On a positive to note, I'm happy to say that we're headed in the right direction with this $1.1 billion dollar allocation to compartive effectiveness research in the stimulus package. Maybe Billy Beane had Mr. Obama's ear?

Women Concentrate on the Wrong Organ (too)

Fear is an interesting concept that I hope to explore more in the future.

In a 2005 study by Women's Health Research, over 1000 women were asked - which disease they feared the most. I was rather surprised they found the fear of Breast Cancer more than doubled Heart Disease. While Breast Cancer caused approximately 3% of the US deaths in 2005, over 22 percent have the most fear for the disease. On the other hand, heart disease accounts for 28.6 percent of diseases and only 9.7 percent consider their top fear!! I know the US society has placed a higher emphasis of breasts over heart, but I can't say I expected this.

Fear Rank																					Disease	Women's Most Feared Diseases										Cause of Death in Women					Difference
1																					Cancer (unspecified)	24.00%										21.60%					2.40%
2																					Breast Cancer	22.10%										3.24%					18.86%
3																					Heart Disease	9.70%										28.60%					-18.90%
4																					HIV/AIDS	9.30%										2%					7.30%
5																					Alzheimer’s Disease	4.60%										3.40%					1.20%
6																					Ovarian Cancer	2.70%										1.30%					1.40%
7																					Lung Cancer	2.40%										5.62%					-3.22%
8																					Diabetes	2.40%										3.10%					-0.70%
9																					Colon Cancer	1.60%										1.94%					-0.34%
10																					Stroke	1.20%										8.00%					-6.80%

So what are the possible explanations for this?

High Incidence?
-While the mortality of breast cancer is low, there is a significant amount of women living and bravely battling the disease. On the other hand, the same can be said about heart disease.

Feeling of Control
-While risk factors such as diet, obesity, and hormones have been established, the cause for breast cancer can still be considered quite a mystery. So most women likely believe that she could develop BC and don't have the power to control it. The risk factors for heart disease - (diet, physical activity, smoking) are a bit more established, so women's feeling of control may be stronger for CHD.

Public Exposure
-Another explanation is that breast cancer has had stronger activists, fundraisers, and lobbyists that push the disease into the mainstream. The general wisdom may be that since Breast Cancer is getting the same or more ad time than Heart Disease - women's risk of death are great for BC.

*Edit*
Age of Disease
Women may believe that they are more likely to get Breast Cancer at a younger age than Heart Disease. According to SEER the median age of dianosis is 61, while the median age of death is 69. For heart disease the average age of a first heart attack is around 70 years old (though the disease can be caught at a much earlier stage).

Women still believe it's a male disease
The stereotypical person with heart disease (at least in my mind) is an overweight, red faced guy in a suit. Women only comprise of about 25 percent of heart studies, and things like this need to change.

Conclusion:
Heart disease kills about 8 times the women than Breast Cancer. The medical community needs to do a better job about expressing this risk. Maybe when people go to their primary doc, they should be asked this "what disease do you fear the most" question. Then the education can begin. Another idea is instead of counseling by doctor, people should have a "medical counclier" who discuss peoples risk of disease and what they can do for prevention. According to the Women's Heart fact sheet only 2 percent of the NIH budget is spent on prevention, and that is just flat out wrong .

2005 data from:
CDC
Women's Health Research
Women's Heart Fact Sheet

Vaccines, Autism, and the Stupid Media

From the Economist:

Why the sudden spike in Measles when we have a vaccine?

"The rise, says the HPA, is due to a fall in vaccination rates. In 1998 91% of two-year-olds were immunised, but by 2004 that had fallen to 80%, far below the 90% rate needed to keep the disease under control....Happily, the dip in vaccination seems to have been temporary. Immunisation rates today are 85% and rising"

Why the drop in Vaccination rate?

Thank you Dr. Wakefield....

"In the UK, the MMR vaccine was the subject of controversy after publication of a 1998 paper by Andrew Wakefield et al. reporting a study of twelve children who had autism spectrum disorders and bowel symptoms, in many cases with onset observed soon after administration of MMR vaccine.[23] During a 1998 press conference, Wakefield suggested that giving children the vaccines in three separate doses would be safer than a single injection. This suggestion was not supported by the paper, and several subsequent peer-reviewed studies have failed to show any association between the vaccine and autism.[24] Administering the vaccines in three separate doses does not reduce the chance of adverse effects, and it increases the opportunity for infection by the two diseases not immunized against first.[24][25] Health experts have criticized media reporting of the MMR-autism controversy for triggering a decline in vaccination rates.[26]
In 2004, after an investigation by The Sunday Times,[27] the interpretation section of the study, which identified a general association in time between the vaccine and autism, was formally retracted by ten of Wakefield's twelve coauthors.[28] The Centers for Disease Control,[29] the Institute of Medicine of the National Academy of Sciences,[30] the UK National Health Service[31] and the Cochrane Library review[9] have all concluded that there is no evidence of a link between the MMR vaccine and autism.
In 2007 Wakefield became the subject of a General Medical Council disciplinary hearing over allegations that his research had received funding related to litigation against MMR-vaccine manufacturers, and had concealed this fact from the editors of The Lancet.[32] It was later revealed that Wakefield received £435,643 [about $780,000] plus expenses for consulting work related to the lawsuit. This funding came from the UK legal aid fund, a fund intended to provide legal services to the poor.[27]"

It's sad what the scientifically illiterate media has done to this issue. I'm also disappointed in the political leaders like Tony Blair who would not reveal if his child was vaccinated or not. You don't mess with diseases like Measles when there is no scientific or epidemiological backup on the subject. Some random doctor speculating does not count...

US Trend in Tobacco Use and Lung Cancer Mortality

A question was proposed in the comments of the previous entry - how has smoking rate changed after the GIs had been given cigarettes in their rations during World War 2 (early 1940s).

The following graphic displays this trend well. It also shows the lag in time of tobacco use to lung cancer mortality. It's nice to see both the cigarrette consumption and lung cancer mortality decreasing, but sadly this is not true in developing asian and african countries where ciagrette use is becoming very common.

Source: ACS 2008 Cancer Statistics Presentation

The graphic below displays the amount of different cancer deaths that can be attributed to smoking. Lung cancer greatly outranks the rest of the cancers, with an attribute rate of 80-90 percent. However only 20 percent or so of smokers end up with lung cancer, due to other risk factors such as genetics, amount smoked, etc.

Source: ACS Cancer Facts and Figures

Top Cancers in the United States

Here are the most popular figures in general cancer epidemiology - a flavor of things to come for this blog. Please share ideas on what to show in the future.

Notice how deadly Lung, Pancreas , and Leukemia - comparing their incidence and mortality rates. It's interesting how little you hear about Pancreas, Ovary, etc - it's probably because the 5 years survival is so low that there is much less pressure to lobby for these diseases. Overall Men have a 1 in 2 chance of developing cancer in their lifetime, while Women have a 1 in 3 chance.

The jump in prostate cancer in the early 90s is due the PSA screening coming into the mainstream. PSA screening is still controversial today - it has not been proven to extend/save lives as of yet. With prostate cancer's five year survival rate of 99 percent, epidemiologists are asking: should we put putting men through this?

Male death rates over time - notice how lung how over-trumped them all due to tobacco use. The disappearance of stomach cancer is still a bit mysterious.


Lung cancer has recently become the number 1 killer for females, due to a later development of tobacco use. Breast and colon cancer, which diet is a major risk factor, are well ahead of the rest of the cancers

Stat of the Week: Tobacco Deaths

"But if global adult smoking prevalence declines to 20% by 2020, at least 100 million fewer people currently alive will be killed prematurely by tobacco."

How to prevent 100 million deaths from tobacco
Thomas R Frieden, Michael R Bloomberg

Stat of the Week: Life Expectancies in Baltimore

20-year life gap separates city's poorest, wealthy

"In West Baltimore's impoverished Hollins Market neighborhood, where the average life expectancy is about 63 years...Across town in wealthy Roland Park, where residents live on average to be 83"

It's crazy how great the dispairites are between two locations within a few miles of each other. Infant mortality and violence are probably the biggest contributors to this difference.

Abortion

Like the author of this article I believe abortion should be considered a public health problem.

The hypothesis is based on this research paper in the journal international family planning perspectives which comes to this conclusion:

Abortion rates are no lower overall in areas where abortion is generally restricted by law (and where many abortions are performed under unsafe conditions) than in areas where abortion is legally permitted.

The evidence is there to make the correct public health decision - but instead of promoting sex education and other social measures, the United States wastes their time with whole roe vs. wade (life/choice) argument. I feel both sides of the aisle are looking at this problem in the wrong way - we can have life and choice, but we're too blind to see it.

I can't say I'm a huge fan of that research paper and there are probably some flaws in it. However the issue is - why aren't we talking about roe v. wade instead of just saving lives?

Other people are a lot more passionate about this issue than I am, so maybe someone can enlighten me.

Stat of the Week

Johns Hopkins study - number of deaths in Iraq

• Estimated 654,965 additional deaths in Iraq between March 2003 and July 2006

Now over 1 million?

What is up with Michigan?

I am bit biased against Michigan because of one of their football teams currently holds a 9 game winning streak against my alma mater (which will hopefully be broken tomorrow).

However, I found this story which we discussed in class especially odd:

The NYT described it like this: "1,000 people who attended a ''rave'' in Michigan and allegedly shared a pacifier dipped in the drug Ecstasy were urged to see a doctor after meningitis was diagnosed in one of them."

-Not only is the pacifier part a bit weird, but supposiedly these teens attended this rave in the middle of a corn field. Really a cornfield?!

Fat Asians

Obesity is a huge emerging problem that I talked about last month. The most common measurement is BMI, which is flawed in many ways. BMI or Body Mass Index measures your weight compared to your height. It does not take into account muscle or particularly kind of fat (healthly or non-healthly). Muscular men seem to be considered overweight (>25 kg/m^2) or obese (>30 kg/m^2) even appearing very fit and having very low % body fat.

Muscular men are not the only ones mischaracterized by this measure; a 2004 Paper from the Lancet suggests that Asians are at greater risk of obesity related diseases (cardiovascular disease, diabetes) at lower BMIs than Caucasians. Asians appear to have increased subcutaneous and upper body fat that is not captured by the BMIs. These fat measurements can be captured in other ways like body fat percentage....

a study in new york measured the following:

Body Fat % at BMI of 25 kg/m^2
Males: Whites: 19.2, Asians: 23.6

Females: Whites: 34.2 Asians: 36.8

Based on the these finding in others the WHO recommended (pdf) the following:

"For many Asian populations, additional trigger points for
public health action were identified as 23 kg/m2 or higher,
representing increased risk, and 27·5 kg/m2 or higher as
representing high risk. The suggested categories are as
follows: less than 18·5 kg/m2 underweight; 18·5–23 kg/m2
increasing but acceptable risk; 23–27·5 kg/m2 increased
risk; and 27·5 kg/m2 or higher high risk."

To summarize/oversimplify, an overweight Caucasian has a BMI over 25, while an overweight Asian has a BMI over 23. No worries my deceivingly chubby Asian friends, the WHO also mentions that the overweight cutoff varies by Asian population from 22-25. My suggestion for those of all races is to get your body fat percentage measured along with your waist/hip ratio - assuming you need more motivation to eat healthy and exercise (or if you just like numbers). Hopefully in the future the health community can improve on the BMI measure and use a less archaic measurement that is less misleading.

Cell Phones and Brain Cancer

Figure 1. Estimation of the penetration of electromagnetic radiation from a cell phone based on age (Frequency GSM 900 Mhz) (On the right, a scale showing the Specific Absorption Rate at different depths, in W/kg) [ ]
Today I saw Devra Davis lecture about her new book, The Secret History of the War on Cancer. In the book she discusses the controversial topic of Cell Phones and Brain Cancer comparing it to the Tobacco/Lung Cancer relationship back in the 50s.

Her main points were:
-We don't have enough evidence to make conclusions one way or another
-Previous studies (which mostly have shown no association) have been biased, cell phone users included anyone who made in a call in the past 6 months
-Huge increase in use has only happened in past ten years, cancer takes 20-30 years to develop.
-Particularly concerned about children's increased use of cell phones, since skulls are thinner and brains aren't not fully myelinated. (see above figure)
----------
This NY Times article provides a more balanced view:

"According to the Food and Drug Administration, three large epidemiology studies since 2000 have shown no harmful effects. CTIA — the Wireless Association, the leading industry trade group, said in a statement, “The overwhelming majority of studies that have been published in scientific journals around the globe show that wireless phones do not pose a health risk."

The F.D.A. notes, however, that the average period of phone use in the studies it cites was about three years, so the research doesn’t answer questions about long-term exposures. Critics say many studies are flawed for that reason, and also because they do not distinguish between casual and heavy use.

Cellphones emit non-ionizing radiation, waves of energy that are too weak to break chemical bonds or to set off the DNA damage known to cause cancer. There is no known biological mechanism to explain how non-ionizing radiation might lead to cancer."
-----------
Studies that have shown risk have unalarming low Odds Ratios:

Meta-analysis of long-term mobile phone use and the association with brain tumours

Abstract:
We evaluated long-term use of mobile phones and the risk for brain tumours in case-control studies published so far on this issue. We identified ten studies on glioma and meta-analysis yielded OR = 0.9, 95% CI = 0.8-1.1. Latency period of ≥10-years gave OR = 1.2, 95% CI = 0.8-1.9 based on six studies, for ipsilateral use (same side as tumour) OR = 2.0, 95% CI = 1.2-3.4 (four studies), but contralateral use did not increase the risk significantly, OR = 1.1, 95% CI = 0.6-2.0. Meta-analysis of nine studies on acoustic neuroma gave OR = 0.9, 95% CI = 0.7-1.1 increasing to OR = 1.3, 95% CI = 0.6-2.8 using ≥10-years latency period (four studies). Ipsilateral use gave OR = 2.4, 95% CI = 1.1-5.3 and contra-lateral OR = 1.2, 95% CI = 0.7-2.2 in the ≥10-years latency period group (three studies). Seven studies gave results for meningioma yielding overall OR = 0.8, 95% CI = 0.7-0.99. Using ≥10-years latency period OR = 1.3, 95% CI = 0.9-1.8 was calculated (four studies) increasing to OR = 1.7, 95% CI = 0.99-3.1 for ipsilateral use and OR = 1.0, 95% CI = 0.3-3.1 for contralateral use (two studies). We conclude that this meta-analysis gave a consistent pattern of an association between mobile phone use and ipsilateral glioma and acoustic neuroma using ≥10-years latency period.
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My Conclusions:
1. Chances are there is little or no risk increase for general population, but even a small risk increase would be a big public health problem since billions of people use cell phones.
2. The lack of known biological mechanism is huge and the major reason the FDA and scientists aren't freaking out
3. Studies should be particularly concentrated on children
4. Time will tell, hopefully we can gather more evidence and not be slow to action like with tobacco (if there happens to be causational evidence).
5. If worse comes to worse, we can always go back to the Banana Phone...

Epidemiology Theories - Pre-Hopkins

Theories I have one month into my Hopkins education:

1. Life expectancy in the US will decrease in the near future
-too many w/o health insurance
-expectancy (~80) all ready close to human max (~100)
-America going down the drain (stupid wars, huge debt, not funding/encouraging science)
-obesity epidemic

2. Environment is a much greater factor than Genes

-Genome Wide Association studies have shown little
-BRAC1/2 an exception, but possibly no others quite like it

-Personal genetics companies like 23 and me will lead to over analyzing of genes
-However genes play a part in basically every disease (average approx 25 percent per disease?)

3. In terms of health disparities Social Economic Status (SES) is a much greater factor than race

-Race over analyzed - possible since it's easy to measure?

-SES underdeveloped, needs a less arbitrary definition (make a uniform one?)
-However separation of groups and evolution gives more reason for race

4. Future in GIS (Geographic Information Systems) and Biomarker studies
-GIS used by gov't to identify disease clusters and disparities
-Biomarkers help reduce bias, identify diseases and potential diseases at earlier stages

5. Measures will be found to greatly reduce bias
-A well done small study (w/ biomarkers) is greater than a huge sample with surveys.
-find other ways to evaluate disease without relying on human memories.
-technology will greatly help in this area - measuring risk factor/food intake via cell phones, etc

6. Obesity will not be the next smoking in this generation
-people too lazy to exercise (much harder than quitting smoking?)
-does not have the obvious ability to harm others like smoking (2nd hand)
-very difficult to turn food into something "evil" (like cigarettes)

7. Poor health education (stubbornish?) is public health biggest enemy
-public over interprets studies - we should ignore unless it increases Risk by 300 percent. Current example: BPA (poor done study showed 2x increase in heart disease, Nalgene removes it from bottles - even though FDA and well done studies are on other side).
-ignoring studies - alarming increase in vaccine distrust (people need to see a disease to be afraid?)
-huge health disparities between education classes


We'll see how my Hopkins education alters my views....