June 24, 2013

Risk Factors: More Risky Than You Might Think

By  Michael D. Shaw

It seems my sardonic remark from the first paragraph of last week’s article struck a nerve. I heard from a number of readers who want me to expand on “[R]isk factors do a much better job of selling drugs than preventing diseases…”

The first expansion would be this: Risk factors do a much better job of selling drugs and diagnostic tests than preventing diseases. But, let’s take this back a few steps. First of all, what is a “risk factor”? One of the better definitions has it: A characteristic, condition, or behavior, such as high blood pressure or smoking, that increases the possibility of disease or injury.

But even this definition could be improved. Properly understood, risk factors are associated with the increased possibility of disease or injury. After all, correlation is not causation! The term was first used in the late 1940s, likely stemming from the Framingham Heart Study in which such factors as cigarette smoking, elevated blood cholesterol, and high blood pressure were said to be predictors of one’s likelihood of dying from heart disease.

Again, though, we must step back. Physician Edward Jenner (1749-1823) is justly famous for turning the observation that milkmaids seldom got smallpox into the practice of inoculating patients to render them immune to the disease. Here was a negative risk factor that led to the eventual eradication of a once dreaded disease, even if Jenner did not use that term.

It would not be until the 1950s that any risk factor finding even remotely as good as Jenner’s would appear. That, of course, was primarily the work of another Englishman—Richard Doll (1912-2005), who documented the extreme correlation of cigarette smoking with lung cancer. It is estimated that 90 percent of all cases of lung cancer are caused by smoking, or to be more precise, occur in individuals who have smoked.

No chemical agent or lifestyle factor has ever come anywhere near such correlation with a disease, and it is quite doubtful that another ever will. But that doesn’t stop people from constantly proclaiming such correlations—touting them as would-be risk factors—virtually nonstop. Sadly, the “science” behind most of these pronouncements—and it matters not how esteemed the source—is questionable at best.

Yet, go to any major health website to read up on any significant disease, and you will surely find the risk factors. One of the more well-known is that being obese is a big risk factor for type 2 diabetes. As mentioned last week, someone came up with the figure that 80 percent of type 2’s are overweight. OK, let’s do the math.

According to the American Diabetes Association, 25.8 million children and adults in the US have diabetes, and this number includes 7 million who are undiagnosed (how does that work?). 90-95% of these have type 2, so that puts it at 24.5 million cases of type 2 diabetes. And, if 80% of these folks are overweight, that gives us 19.6 million corpulent type 2’s.

Now, how many people in the US are obese? We are told that 35.7% of adults fit this qualification, so let’s just apply it to a total population of 314 million. That gives us 112.1 million, of which 19.6 million are type 2’s.

Thus, our big risk factor correlating being overweight with type 2 diabetes proves out at a measly 17.5 percent, and that’s with all best case scenario assumptions in play. In reality, it could be much lower. Compare this to the 90 percent figure for smoking and lung cancer. Bear in mind that outside of smoking/lung cancer, the obesity/type 2 diabetes connection is the most highly publicized risk factor in public health.

With hundreds of fear-inducing risk factors extant, patients flock to all sorts of recommended diagnostics, and take many drugs whose sole purpose is to adjust blood titer numbers, indicative of a so-called risk factor.

Drs. H. Gilbert Welch, Lisa Schwartz, and Steve Woloshin collaborated on the 2011 book Overdiagnosed: Making People Sick in the Pursuit of Health. Following the book launch, Welch was interviewed by Lisa Chedekel of BU Today, and offered these remarks:

A lot of people [benefit from overdiagnosis]: Pharma, device manufacturers, imaging centers, and even your local hospital. The easiest way to make money isn’t to build a better drug or device—it’s to expand the market for existing drugs and devices by expanding the indication to include more patients. Similarly, for hospitals, the easiest way to make money isn’t to deliver better care; it’s to recruit new patients—and screening is a great way to do this.

The poster child for the problem [of overdiagnosis and overtreatment] is prostate cancer screening: Twenty years ago, a “simple blood test” was introduced; 20 years later, over one million Americans had been treated for a cancer that was never going to bother them. The test was the PSA. It’s able to detect minute quantities of prostate-specific antigen—minute as in one-billionth of a gram. Turned out a lot of men had ‘abnormal’ PSAs. Many were found to have microscopic cancers—far more than would ever suffer from prostate cancer. So they were overdiagnosed.

Does it matter? Absolutely. Most were treated with either radical surgery or radiation. Roughly a third suffered side effects of treatment—generally related to bowel, bladder, or sexual function. And a few have died from it.

Sounds risky to me.