How Reliable Are Those Test Results?

When you go to your doctor with one complaint or another, the most common response is, “Let’s run some tests.” You and your physician both expect that with those results in hand, you’ll have a better idea of what’s going on and can work toward a solution.

Of course, anyone who’s seen an episode of House knows it’s not always that simple. But even when your symptoms aren’t due to some obscure condition, there’s a complicating factor: the test results may not give the right answer.

How Things Can Go Wrong

We need to get into statistics again, if only briefly. There are four possible outcomes of a test:

  1. You have the condition, and the test says that you do. This is known as the sensitivity of the test.
  2. You have the condition, but the test says that you don’t. This is called a false negative (in statistics lingo a “Type 2” error).
  3. You don’t have the condition, but the test says that you do. This is a false positive (a “Type 1” error).
  4. You don’t have the condition, and the test says you don’t. This is the specificity of the test.

A Type 2 error leads to not getting treated for something you have, while a Type 1 error leads to unnecessary treatment for a condition you don’t have—or, more importantly, instead of the condition you do have. (If you’d like to wander into the weeds of statistical methods, here’s a good explanation of the errors from Mark Liberman, a professor at the University of Pennsylvania.)

Tests can go wrong for any number of reasons. They can be misread or misinterpreted, for example on an x-ray or sonogram. Or they can be based on uncertain data, as in PSA testing. What caught my eye was some recent news about kidney damage.

Good Tests Can Lead to Bad Treatments

Many medications can cause damage to your kidneys—pain relievers, antibiotics, and drugs for heartburn among them. Certain health conditions can injure your kidneys as well, chiefly high blood pressure and diabetes. Kidney injury is usually diagnosed by measuring levels of a protein called creatinine; more particularly, changes in the level of creatinine.

A study published in last week’s Clinical Journal of the American Society of Nephrology showed that blood tests for levels of creatinine can result in a false diagnosis of kidney damage (specifically, acute kidney injury) an average of 8% of the time. That may not sound like much of an error, but in people with higher levels of creatinine to begin with, the error rate rose to 30%.

The implication is that your physician may be making treatment decisions based on these test results. The most drastic decision is to begin dialysis, but he/she may also withhold an effective treatment because of known effects on the kidneys, such as the pain relievers I mentioned earlier.

For you, here’s what this means. Whenever you see test results that are out of the normal range, dig further. Before beginning any treatment based on those results, ask your doc what the error rate is and how that rate affects the decision. (They may be surprised to hear that question, and in fact may not even know.) It’s part of being a smart consumer.

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Nobody’s Breathing Easier Around Here

I was scrolling through statistics on drug sales recently, looking up information for another post. I found something that shocked me right down to my socks. For as long as I’ve been following this information—more than 20 years now—the number-one selling drug in terms of prescriptions written has been a painkiller. Most recently this has been the opiate hydrocodone plus acetaminophen, the popular Vicodin.

Now 38 million scripts a year is a lot of prescriptions, but I do understand how this could happen. The trend makes sense to me because so many people experience distracting pain at some point during a year. I’ve taken one or another of these drugs for dental issues and for a broken rib. But pain relief has taken a back seat to drugs for breathing difficulty.

A Breath of Fresh Air? Hardly

In 2013 (the latest year available) the number-one selling drug in this country was generic budesonide, a drug used to treat asthma. The shocking part for me is that budesonide is joined by 3 more breathing drugs in the top 10, and another 5 among the top 75 sellers. That’s more than 120 million prescriptions all told in 2013. Some of these later 8 are also used to treat COPD—chronic obstructive pulmonary disorder, a catch-all phrase that includes emphysema and chronic bronchitis.

As a child I had allergy-related asthma. I eventually mostly grew out of the allergies, and a damp summer night is about the only thing that bothers me now. I still have a prescription inhaler around for occasional use (but I think it’s about 10 years old by now—maybe time for a replacement). Allergies in general seem much more prevalent now overall, so I suppose the increase in respiratory drugs is related to that. And when you look at sales statistics, the asthma drugs are very seasonal—peaking during the winter—while those primarily for COPD have a much more level sales trend.

Maybe this is all related to people living longer. Or maybe it’s the long tail of the tobacco use dragon. It could be related to lung damage from other prescription meds. Or the allergy piece. Whichever, there are many, many people out there on meds for lung health.

The Drug of a Lifetime

After yesterday’s post about the overuse of statin drugs in the elderly, this morning I came across the results of a recent study investigating medications for high blood pressure.

Stop, I Say!

Actually, the study looked at patients who stop taking meds for high blood pressure. Several recent studies have noted that higher blood pressure in the elderly is associated with better brain function, so the investigators wondered whether taking patients off their medication would help those who had some degree of cognitive impairment.

After 16 weeks, those patients who had stopped their medication didn’t do any better on cognitive tests than those who continued on the drugs. There was also no difference in other aspects of mental function, such as mood, memory, and quality of life. The researchers were somewhat surprised, and guessed that they hadn’t tracked the two groups for long enough to notice a difference.

The premise is that brain function depends on adequate blood flow, so maintaining a higher volume and pressure of blood through the brain might improve things, or at least keep function from deteriorating. But other trials had shown that lowering blood pressure in the elderly didn’t change brain function either, so it’s possible that BP doesn’t affect the brain in either direction. The flip side of this is that stopping medication for high blood pressure won’t cause harm to the brain, either.

We’re All Lab Rats Now

As it happens, I’m especially interested in meds for blood pressure, because I have a family history of the condition—in both parents and my younger sister—and it’s the only medical condition I have. My doctor prescribed a relatively benign medication for me, a beta blocker. Still, I’m not happy about the idea of a lifetime of morning pills. For one thing, it’s a pain. And for another, our generation is part of a giant on-going experiment—and we’re the lab rats.

Drug trials are considered long-term if they go beyond 6 months or so, and new drug approvals are based on the risk/benefit ratio that appears in that short time. (See my recent post about Addyi/flibanserin, for example.) That’s simply not enough time to get the full assessment of truly long-term risks and benefits.

Since 1995, 26 drugs have been withdrawn* from the US market after having been approved by the FDA. Some of these had been around for more than 20 years; it took that long for reports and observational studies to pick up the pattern of adverse effect from these drugs. And granted that this is an outlier, but one drug, DES, is currently under review for adverse effects in the grandchildren of women who took it in the ‘50s and ’60s to prevent complications in pregnancy.

One review of the study above said that it represented a “paradigm shift” in the way we conduct trials on lifetime medications. Hooray for that.

* “Market withdrawal” means that the FDA pushed the maker to stop manufacturing and distributing the drug in the US permanently, mostly for reasons of safety. A “recall” occurs when the FDA requires a maker to pull something from the market. This is usually over a temporary issue, such as a manufacturing glitch or labeling problems. Recalls most often apply to specific lots or batches of a drug, and seldom affect its long-term future.

Treatments for Allergies That, Well, Don’t Work So Well

Yesterday I told you about some non-drug therapies that work well for some people in reliving seasonal allergies (and year-round ones, too). Here are two that have plenty of word-of-mouth support, but not much in the way of research to back them up.

Honey

Honey seems like the perfect solution for seasonal allergies. After all, the standard “cure” for allergies is regular injections of tiny amounts of known triggers, a process known as desensitization. And for many people who have seasonal allergies, the biggest culprit is pollen. What’s in honey? Pollen, of course.

Unfortunately, clinical trials using raw local honey have not found any benefit for common allergy symptoms. In one trial, 12 people received one teaspoon of local, unfiltered, unpasteurized honey a day. Another 12 received grocery store honey, and another 12 honey-flavored sugar syrup. There was no difference in symptoms among the groups after several months of daily use.

One study from 2011 showed that birch pollen honey was effective in reducing symptoms in people who were allergic to birch pollen. It’s important to note though, that this was regular honey that had birch pollen added to it by the researchers, not straight-from-the-hive honey. The people in the study who used regular local honey didn’t see any benefit.

So why doesn’t honey measure up? Pollens that trigger allergic symptoms tend to have small grains that are easily blown around. The pollen in honey is generally from plants with larger pollen grains that are more easily collected by bees and other insects.

If you happen to be allergic to the pollen from clover, or orange blossoms, or sourwood (my favorite!), then you may see some benefit from regular consumption of a teaspoon a day. Otherwise, it’s not likely. If you do decide to give honey a try, check around for a local beekeeper.

Apple Cider Vinegar

This is the mother of all folk cures. Apple cider vinegar is supposed to be the remedy for everything from arthritis to high cholesterol.

A quick search of the web provides dozens, maybe hundreds of anecdotes about how apple cider vinegar (ACV) relieved someone’s allergy symptoms after just a few days. Unfortunately, there are no studies—not one—looking at the use of apple cider vinegar for allergy symptoms.

Still, people swear by ACV. They have their own way to take it: how much, what time of day, what to mix it with. There’s certainly no harm in taking a couple tablespoons of ACV daily. You’ll want to water it down, and probably add a sweetener or other flavoring to cut the sour taste.

One consistent recommendation for ACV is that you want it raw and unfiltered. Look for a product such as Bragg’s at health food stores or on the web.

A Quick Note About Carter’s Cancer

We seem to be getting daily updates about the condition of former President Jimmy Carter. The news in this morning’s paper was that his cancer has spread to his brain. And, curiously, that the spots on his brain were found during surgery on his liver. I guess when you’re a Nobel winner you get the super-duper scans.

At any rate, the interesting thing is that he doesn’t have brain cancer. Instead, he has melanoma (a form of skin cancer) in his brain. That’s the way cancer works. When, for example, breast cancer spreads to the liver, the person doesn’t now have liver cancer. Instead, they have breast cancer in both the breast and the liver. The cells spread through the lymphatic and circulatory systems, taking root where they will. Fortunately, a treatment that’s successful against the original cancer has a good chance of success against the metastatic site.

As I mentioned in an earlier post on sun safety, melanoma is the most serious form of skin cancer. President Carter’s melanoma is considered Stage IV, meaning that it has spread to another organ. The statistics are grim: only 15-20% of patients survive another 5 years, and just 10-15% make it for 10 years. His chances are improved by the fact that he’s receiving a novel combination of drugs that has shown promise in melanoma. His chances are diminished because he is, after all, 90 years old. (But don’t forget, his mother, Lillian, lived to age 85. He comes from hardy stock.)

Jimmy Carter is a good man. He’s a wonderful model for life after your “career” is over. I wish him the best.

Is Table Salt Really Bad for Your Blood Pressure?

Table salt has been demonized when it comes to blood pressure. Public health campaigns urge people to reduce their salt intake, and doctors ask about it at office visits. The message seems to have taken hold; a report in this week’s MMWR (Morbidity and Mortality Weekly Report, the CDC’s weekly update on diseases) says that about half of adults are either watching their salt intake or taking steps to reduce it.

The bad reputation is undeserved, though. Table salt is perfectly fine for you, when used moderately. In fact, your body needs salt to function properly. Some studies show that too little can worsen problems with both cholesterol and insulin.

So why all the buzz? Breathless news headlines in 2013 proclaimed that 10% of all deaths in the US can be linked to our excessive salt consumption. Groups from the World Health Organization to the American Heart Association recommend cutting our national salt intake by half or more.

The Real Culprit in High Blood Pressure

There’s no question we consume lots of salt. The guilty party, though, appears to be the sodium in salt. On average, Americans consume about 3.6 grams of sodium daily, which is just a little less than the world average of 4 grams daily. If we got all that sodium from table salt, it would come to nearly 2 teaspoons. There’s more sodium in our diets than just table salt, though.

Practically every processed food out there contains sodium in one form or another. Sodas and fruit juices contain sodium benzoate, used as a preservative. Processed meats contain sodium nitrate, also as a preservative.

The most widely used sodium source is MSG, or monosodium glutamate, found in everything from ketchup to ice cream. It’s bad enough that MSG is such a prevalent source of sodium. In addition, though, MSG has been linked to a seemingly endless list of health problems. Nearly 20 years ago a special editorial supplement in the Journal of Nutrition listed all the known reactions to MSG, including burning sensations, difficulty breathing, chest pain, and changes in heart rate.

(As a side note, there’s lots of noise on the web and elsewhere about how MSG “hides” under names such as textured vegetable protein, autolyzed yeast, and hydrolyzed protein, which can cause the same health reactions as MSG. In fact, these reactions are due to the other part of MSG, glutamic acid, which is formed during processing of the protein. If you’re sensitive to MSG, then certainly do watch out for these ingredients, but they won’t have any effect on your sodium intake.)

When you look at statistics on individuals, it appears that those who consume more sodium are at greater risk of high blood pressure. And it’s clear that higher blood pressure increases your risk for all sorts of health conditions. But a 2013 report by the Institute of Medicine reviewed 38 clinical studies on the effect of sodium consumption on overall health. They found that sodium intake had no effect on the ultimate outcome (death), and in fact for several groups the current dietary guidelines were actually harmful.

Some people are sodium-sensitive—but it’s less than a third of us. (The rate of sodium sensitivity is significantly higher among African-Americans.) If you are one of the few who are sodium-sensitive, it does make sense to watch how much salt you consume. The biggest culprit is prepared food, especially restaurant food. Some meals contain more than 5 grams of salt. (Check the restaurant’s menu online to get nutritional information.) And while one of these meals every now and then won’t give you high blood pressure, if you’re one of the many folks who eat out more than once a week or so then all the extra salt can add up.

The Vaccine Controversy That Won’t Go Away

(Part 2 of 2)

In yesterday’s post I wrote a little about the current vaccine controversy in California that’s been ignited by proposed legislation. Today I’ll go into some detail about how vaccines work (or don’t), and why that matters to you.

The idea behind vaccinations is simple: you get a small dose of a disease, mild enough that you can recover from it, and then you forever have immunity against catching that disease again. It’s essentially training your immune system to recognize a particular invader, and giving it what’s needed to fight off the bug if it shows up again.

So common vaccinations, such as the one known as MMR (for measles/mumps/rubella) can actually give you a mild case of the measles, of the mumps, and of rubella (German measles)—all at the same time. As you can imagine, mild reactions to these vaccinations are common: redness, swelling, or discomfort at the injection site, mild rash; low-grade fever for a few days; etc.

For adults, who generally have more fully developed immune systems, the triple shot is generally not a problem. The vaccine controversy has arisen because these composite vaccinations are usually given to young children, who haven’t had time yet for their immune systems to develop. From time to time a child will develop a very high fever. And in a developing brain, a very high fever can cause irreversible damage. No parent wants to be the one who causes harm to their child. Hence the vaccine controversy: do you give the vaccine, and create the tiny chance that something might go wrong, or do you withhold the vaccine, and run the risk of your child coming down with a preventable disease?

As I said, the risk of an adverse event on any single vaccination is tiny. But when you put together all the recommended injections—26(!) by age 18 months—the risk gets appreciably larger. If there’s a one percent chance of any single vaccination harming a child, by the time you get through the full series that chance has risen to 22 percent.

We had our daughter fully vaccinated. But that was more than 20 years ago, and the number of recommended vaccinations has more than doubled since that time. I think if I were bringing up a child today I’d consider carefully which vaccines to administer.