A Reminder to Dump Your Multivitamin

The Medical Letter is a biweekly publication which publishes the most unbiased reviews of medications. It is not supported by advertising and prides itself in giving objective evidence-based information. I think it’s mandatory reading for anyone with a prescription pad. Several of my posts have been inspired by Medical Letter articles, and this week they’ve come through again with a review of vitamins titled “Who Should Take Vitamin Supplements?” The article reviews in detail the clinical trials which have tested the effects of the most commonly taken vitamins. I summarize these below.

Vitamin E supplements have been shown to increase the risk of prostate cancer, not to decrease the risk of stroke or heart attack, and not to decrease the risk of eclampsia in pregnancy.

Beta-carotene is a precursor of vitamin A. A randomized trial in smokers found that a high dose beta-carotene supplement significantly increased the risk of lung cancer. Another randomized study in asbestos workers showed that supplementation with vitamin A and beta-carotene led to higher lung cancer rates than placebo.

Vitamin D is essential in older people in preventing fractures and falls. Many people with limited sun exposure are deficient in vitamin D.

Vitamin C has been shown not to prevent the incidence of cancer, strokes, or heart attacks. It does not significantly decrease the risk of developing a cold or significantly improve cold symptoms. High doses can predispose to kidney stones.

Vitamin B12 deficiency is common in older patients and can lead to anemia and nerve dysfunction.

Folate should be taken by all child-bearing-age women to prevent neural tube defects in their babies. Folate supplementation has no known benefits in men.

Vitamin B6 supplementation has been proven not to decrease the incidence of strokes, heart attacks, or any cancer.

The authors conclude:

“In healthy people living in developed countries and eating a normal diet, the benefit of taking vitamin supplements is well established only to ensure an adequate intake of folic acid in young women and of vitamins D and B12 in the elderly. There is no good reason to take vitamins A, C or E routinely. No one should take high-dose beta-carotene supplements. Long-term consumption of any biologically active substance should not be assumed to be free from risk.”

That last sentence deserves our attention. Many people assume that even if vitamins aren’t helpful, they are at least harmless. The Medical Letter reminds us that this assumption should be tested, and when tested is sometimes proven false.

Learn more:

More Than Half of Americans Take Dietary Supplements (My post in April on multivitamins)
All my previous posts on various vitamins
Who Should Take Vitamin Supplements? (The Medical Letter article, issue 1379, only by subscription)

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Niacin Much Less Helpful in the Age of Statins

Niacin has been getting some bad press recently. A brief retrospective of Niacin’s rise to prominence will help us understand its recent fall from favor.

Niacin is also known as vitamin B3 or nicotinic acid, a molecule that we need in tiny quantities in our food. As far back as the 1950s it was known that niacin in higher doses reduces blood levels of cholesterol. At that time our understanding of heart disease was in its infancy and there were few effective medications to treat or prevent cardiovascular disease.

From 1966 to 1969 a trial called the Coronary Drug Project (CDP) was conducted that would prove to be niacin’s finest hour. The CDP enrolled patients who had suffered a prior heart attack and randomized them to placebo or niacin. My understanding of those years suggests that all the patients wore paisley shirts, had very long hair, rioted outside political conventions, and landed on the moon. The trial showed a reduction in strokes and heart attacks of about 25% in the patients receiving niacin. The CDP findings from over 40 years ago are the strongest suggestion we have that niacin helps prevent cardiovascular disease. The important thing to remember about the CDP is that many of the medications that are now used routinely in patients with heart disease, like aspirin and certain blood pressure medicines (beta blockers) were used rarely then. But that’s not surprising. After all, back then we thought that polka dots and hair were attractive in any quantity. Can you dig it?

Fast forward twenty years. The paisley and polka dots were replaced by skinny ties and Ray-Bans. The first statin, lovastatin (Mevacor), appeared on the market in 1987. My regular readers know that statins are a family of cholesterol-lowering medications which have been extensively proven to prevent strokes and heart attacks. Statins are also the most potent reducers of LDL, the cholesterol molecule most linked to stroke and heart attack risk. Meanwhile, other medications like aspirin and beta-blockers were proven to extend life and prevent heart attacks in people with prior heart attacks. The management of heart disease was progressing by leaps and bounds, and mortality from heart disease has been decreasing ever since.

So statins rapidly overshadowed niacin for management of cholesterol, and for good reasons. Niacin has side effects that are more difficult to tolerate, it lowers cholesterol less, and the evidence of its ability to prevent strokes and heart attacks is largely from one study – the CDP. Nevertheless, niacin has continued to be prescribed, largely because it has one benefit that statins don’t have. Niacin elevates the levels of HDL, a cholesterol molecule that is associated with lower heart attack and stroke risk.

This year a large trial called AIM-HIGH attempted to answer whether niacin taken with a statin is superior to a statin alone in patients with cardiovascular disease and low HDL. I wrote about the AIM-HIGH study in May when it was completed but before the full results were published. The full results were finally published two weeks ago. (You may want to read my May post for details about the study and for a more detailed explanation of LDL and HDL.)

The study enrolled patients with known cardiovascular disease with low HDL and randomized them to two groups. One group received a statin (simvastatin, sold under the brand Zocor) and niacin. The second group received simvastatin and a placebo. The niacin group had lower LDLs, higher HDLs, and lower triglycerides than the placebo group. But surprisingly there was no difference between groups in the rate of strokes and heart attacks.

What does this mean? Why didn’t better cholesterol numbers translate to better outcomes?

The first possible explanation (which I offered in May) is that low HDL is simply a marker of heart attack risk, not a cause. This is the same reason that putting an ice cube on your thermometer on a very hot day won’t make you feel more comfortable, since the thermometer reading is a marker for your discomfort, not a cause. Another explanation is that niacin alone does have some benefit (as shown in the CDP) but that the benefit of more modern medications is much greater. And that in the presence of statins and aspirin and other proven medications, niacin may not offer any additional advantage. Both explanations may be true.

So we’re likely seeing the waning days of niacin use. It may remain a reasonable option for patients who can’t tolerate statins. For the majority of patients who can tolerate statins, niacin has no value.

Learn more:
No Benefit From Niacin for Heart Patients in Study (US News)
Niacin in Patients with Low HDL Cholesterol Levels Receiving Intensive Statin Therapy (New England Journal of medicine article)
Niacin at 56 Years of Age — Time for an Early Retirement? (New England Journal of Medicine editorial)
Needed: Pragmatic Clinical Trials for Statin-Intolerant Patients (New England Journal of Medicine editorial)
Niacin Does Not Prevent Strokes or Heart Attacks (my post in May about Niacin)

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Reflections on Gratitude

For each new morning with its light,
For rest and shelter of the night,
For health and food,
For love and friends,
For everything Thy goodness sends

Thanksgiving
By Ralph Waldo Emerson

It’s been a difficult year for many of my patients. Some have had catastrophic health challenges. Many businesses are still struggling. Some marriages are fraying. Many of us are very unsure of what comes next.

When things look irredeemably hopeless, when I have nothing but bad news to give, when I really wish someone else was the doctor for one day, that’s when I am reminded what an extraordinary job I have. I am privileged to be a part of people’s lives at their scariest, most personal, darkest times. I hear their anxieties, their confessions, and their secrets. I do my best to help, and to assemble a team of specialists to do the many things I can’t do. But ultimately all help fails.

And the one thing my patients teach me again and again when things are at their worst is gratitude. I hear about the love of family, the comfort of happy memories, the joy of looking back without regrets. In the most desperate situations when I would expect panic or grief, I hear gratitude.

Tomorrow is the day to remember all of our abundant blessings. We all have so much to be grateful for. This year I’m especially grateful to my patients for allowing me to make a living doing what I love, and for reminding me constantly of the importance of gratitude.

As is my annual tradition, I hereby lift all my patients’ dietary restrictions for one day. I wish you happy feasting in homes filled with cheer and joy! Happy Thanksgiving!

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Yoga Or Stretching Helps Chronic Back Pain

Everyone hates stress, and for good reason. Stress makes us miserable. Perhaps for that reason, stress is blamed for virtually every disease for which the cause is still unknown. Later, when we discover the true cause, we find that it is unrelated to stress. We thought stress causes stomach ulcers before discovering the bacterium that is the true culprit. We thought stress caused heart attacks before a study comparing high-stress to low-stress individuals showed that this wasn’t true. Stress causes gray hair? Nope. Genes cause gray hair. Irritable bowel syndrome is probably the next disease on this list. We’re close to sorting out what causes it, and when we do, we can stop blaming stress.

So stress causes misery, which is bad enough, but we should be careful not to scapegoat it for other ills.

A study in the Archives of Internal Medicine last month adds another illnesses for which stress may not be relevant.

Chronic back pain is common and has no universally effective treatment. Lots of patients swear by yoga, and for many with chronic back pain it seems to improve their symptoms. Is this simply because the exercises stretch their backs and legs, or is the breathing and meditative component also helpful? After all, countless people attest to the stress-lowering properties of yoga. Shouldn’t less stress decrease chronic pain?

To test this question, researchers enrolled over 200 patients with chronic back pain and randomized them to three groups. One group attended weekly yoga classes. A second group attended weekly stretching classes. A third group was given a self-care book teaching exercises for low back pain and was asked to follow the book’s instructions independently. All the patients had their functional status and pain levels measured by periodic questionnaires.

As expected, the yoga group did better than the self-care group. But surprisingly, the yoga group did no better than the stretching group. This suggests that the benefit for back pain from yoga is entirely related to the stretching, with no additional improvement from the meditation and breathing exercises.

That’s not to say that the breathing exercises and the meditation don’t feel good, which might be reason enough to do them.

So chronic back pain may be another illness that doesn’t have as much to do with stress as we thought. But stress makes us unhappy and strains our relationships. That’s reason enough to find ways of managing stress.

The holidays are around the corner, which for some of us are particularly stressful. So when you’re feeling very anxious and want to tell a loved one who is annoying you “You’re giving me an ulcer,” remember that he’s not. Take a deep breath and say something like “You’re not giving me an ulcer, a heart attack, or gray hair, but I wish you’d stop anyway.”

Learn more:

Yoga, stretching both ease chronic back pain: US study (Reuters)
Yoga May Help Low Back Pain. Mental Effects? Not So Much (Wall Street Journal)
A Randomized Trial Comparing Yoga, Stretching, and a Self-care Book for Chronic Low Back Pain (Archives of Internal Medicine, abstract available without subscription)

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Difficult to Digest Carbohydrates Implicated in Irritable Bowel Syndrome

Irritable bowel syndrome (IBS) is a chronic condition marked by abdominal pain, bloating, and alternating constipation and diarrhea. There is no specific test for IBS and other more serious diseases like celiac disease and inflammatory bowel disease can cause similar symptoms. The good news is that when a doctor has ruled out these more serious diseases and diagnosed IBS the patient can be assured that her illness is chronic but not progressive or life-threatening. The bad news is that IBS symptoms can be quite miserable, and at their worst can interfere with work and life activities.

Myriad treatments are used for IBS, and as with any disease with myriad treatments, that means that none of them are consistently effective. I wrote five years ago about a trial that showed modest success using antibiotics for IBS but even that trial did not show an improvement in the majority of patients.

A new theory proposed by researchers in Australia holds that IBS is caused by certain sugars that are difficult to digest. These sugars pass undigested through the small intestine and are fermented by bacteria in the colon. This releases carbon dioxide which causes bloating and pain, and draws water into the colon which causes diarrhea.

These carbohydrates are called FODMAPs, which stands for Fermentable Oligosaccharides, Disaccharides, Monosaccharides and Polyols, which just means small sugars that can undergo fermentation.

FODMAPs are present in lots of foods. (This Wall Street Journal article has a handy table with a list of foods high in FODMAPs and low in FODMAPs.) So eliminating them entirely requires some drastic dietary changes. Nevertheless, the Australian researches published a study in last month’s issue of the Journal of Human Nutrition and Dietetics in which patients were randomized to standard care or to a FODMAP-free diet. About half of the patients in the standard group had symptom improvement, compared to about three quarters of those on a FODMAP-free diet.

Gastroenterologists who are promoting this theory recommend that patients try a FODMAP-free diet for six to eight weeks and then slowly reintroduce FODMAP-containing foods to determine what quantities they can tolerate. Unlike food allergies, complete abstinence is not necessary. It’s just a matter of reducing the FODMAPs below whatever threshold causes misery.

Some caveats are necessary. The study was quite small, and it was not blinded since it’s impossible not to know whether your diet is being restricted radically. So the results should be treated as suggestive but preliminary. Still, for those with severe IBS symptoms a FODMAP-free diet may be worth a try. It may be inconvenient but it’s certainly safe and the worst that could happen is that it won’t work.

Learn more:

When Everyday Foods Are Hard to Digest (Wall Street Journal)
Very Restricted Diet May Reduce Symptoms of IBS (WebMD)
Irritable Bowel Syndrome (National Library of Medicine information page)
An Oral Antibiotic Reduces the Symptoms of Irritable Bowel Syndrome (my post in 2006)
Comparison of symptom response following advice for a diet low in fermentable carbohydrates (FODMAPs) versus standard dietary advice in patients with irritable bowel syndrome (Journal of Human Nutrition and Dietetics, abstract available without subscription)

Tangential Miscellany

If you appreciate the right to speak as you wish without fear of censorship or punishment, the right to wave a sign declaring your displeasure with how much income the top 1% earn, the right to occupy public places and protest Wall Street and be generally tolerated, if you value these rights, then thank a veteran. Happy Veterans Day.

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Ivacaftor – a Breakthrough in Cystic Fibrosis Treatment

One of the implicit themes we were taught in medical school is that an understanding of the basic science of a disease informs and guides treatment of patients. The general philosophy that we absorbed was that an understanding of the molecular or cellular defects in a disease would explain the abnormal organ physiology which would explain the patient’s abnormal signs and symptoms. This understanding of the abnormality at a molecular or cellular level would also help discover medications that corrected or ameliorated this abnormality. Just as physics forms the foundation of chemistry which leads to organic chemistry and then to cell biology, we were led to believe that understanding physiology would form a foundation for understanding medicine.

It turns out that this beautiful philosophy is usually wrong.

One reason is that we don’t understand human physiology in nearly enough detail to understand all the mechanisms that malfunction in any disease, or to predict the effects of any treatment. A single mammalian cell is more complex than the most complicated systems engineered by people, and our understanding of the molecular mechanisms that allow cells, tissues, organs and people to function is incomplete. Just to take one example, everything we knew about how estrogen works suggested it should prevent strokes and heart attacks. It doesn’t.

Another reason that medicine is disconnected from basic science is that understanding the molecular basis of a disease frequently gets us no closer to finding a treatment. The best-known example of this is sickle cell anemia, a disease in which the abnormal gene is known, the abnormal hemoglobin molecule produced by this gene is known, the abnormal way this hemoglobin folds is known, the way this abnormal folding disrupts red blood cells is known, and the way the abnormal sickle-shaped red blood cells make people sick is known. And we are still frustratingly far from a treatment directed at the basic defect.

So medicine is usually a deeply pragmatic practice, largely separated from the basic sciences. We know what works because of trials in which medications are actually tried on patients (and first on animals), not from our understanding of molecules, cells or organs. And those medications are usually found serendipitously, not by design. The basic sciences may give us a vocabulary and an intellectual framework, but they rarely give us an actual treatment.

This week, we have a very happy exception.

Cystic fibrosis is the most common fatal genetic disorder in whites, affecting 30,000 people in the US. The gene responsible for it was discovered in 1989. In healthy people, this gene codes for an ion channel – a protein on the cell surface that controls the flow of charged atoms, like chloride and iodide, into and out of cells. In people with cystic fibrosis this protein malfunctions or is absent.

This inability of cells to pump ions where they’re supposed to go leads to an inability to secrete water (which follows the ions). This leads to many of the clinical manifestations of cystic fibrosis. Airway secretions are too dry because airway linings cannot secrete enough fluid. This creates thick mucus that is difficult to cough up, obstructs airways, and predisposes to lung infections. Pancreatic secretions are also too thick, destroying the pancreas.

Patients frequently lose weight because of recurrent infections and because of malnutrition caused by pancreatic failure. They develop progressive decrease of their lung function and eventually succumb to respiratory failure or infection. Forty years ago the median survival age was 11. Now, with better treatment of infections and drugs aimed and loosening secretions, median survival is 37.

Ivacaftor is a medicine that was designed specifically to treat cystic fibrosis. It is a molecule that was designed to keep dysfunctional ion channels open. That means it is only useful for the 4% of cystic fibrosis patients with the specific mutation that causes ion channels to be present, but not working. This week The New England Journal of Medicine published a study testing the effects of ivacaftor in cystic fibrosis patients with this specific mutation.

167 patients were randomized to ivacaftor or to placebo. The differences between the two groups were striking. The ivacaftor group gained weight, had improvement in lung function, and had fewer respiratory exacerbations. The benefits started within two weeks of treatment and persisted for the duration of the trial. And the trial found no serious side-effects.

It’s hard to overstate the significance of this development. For newborns with this specific mutation, ivacaftor may completely reverse their disease. There is reason to hope that if the disease is treated prior to permanent lung and pancreas damage, people will live entirely normal lives apart from taking a pill twice a day. Obviously, more work must be done to substantiate this, as well as to find similar treatments for the cystic fibrosis patients with other mutations.

This is a breathtaking improvement in the care of a disease that was recently a death sentence, and it is a beautiful demonstration that understanding a disease at the molecular level can actually lead to an effective treatment.

Learn more:
Cystic fibrosis drug ivacaftor offers patients new hope (LA Times)
A CFTR Potentiator in Patients with Cystic Fibrosis and the G551D Mutation (New England Journal of Medicine article)
Therapy for Cystic Fibrosis — The End of the Beginning? (New England Journal of Medicine editorial)

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Annual Chest X-Rays Not Useful for Lung Cancer Screening

not for screening anymore

It’s been a disappointing month for proponents of screening.

You remember what screening is? Screening is testing someone for a disease who does not have any signs or symptoms of that disease. In general it means testing a wide population for a specific disease. So if I have a chronic bloody cough and unintentional weight loss, my doctor isn’t screening me for lung cancer. He’s doing tests to diagnose or rule out lung cancer because I have suggestive symptoms for that disease. Got it?

Lung cancer has long been the number one cancer killer in the US. So a screening test that would help save lives from lung cancer is much in demand. In the 1970s studies tested screening for lung cancer with annual chest X-rays. The trials did not find any benefit.

Apparently those 1970s studies had some procedural flaws that made them unconvincing. And X-ray technology has improved in the last 30 years. So it was conceivable that chest X-rays got a bum rap and were actually a valuable screening tool. This prompted the National Cancer Institute to retest chest X-ray screening as part of its Prostate, Lung, Colorectal, and Ovarian Cancer Screening Trial (PLCO) which is a large clinical trial testing various cancer screening tests.

The results of the lung cancer portion of this trial were published in this week in the Journal of the American Medical Association. Over 154,000 people were randomized to either receiving annual chest X-rays or to usual care by their physicians. There was no difference between the two groups in deaths from lung cancer.

So that settles a question I thought was already settled. Healthy people don’t benefit from periodic screening chest X-rays.

This finding comes on the heels of other negative news about screening. The ovarian cancer branch of PLCO has also demonstrated that the blood test CA125 is not valuable for ovarian cancer screening. And just two weeks ago the US Preventive Healthcare Task Force’s recommended against PSA screening for prostate cancer.

For lung cancer, there is some hope, however. A study in July showed that in a selected population of high-risk smokers screening with spiral CT scans saved lives.

Avoiding unproven tests isn’t just a matter of avoiding expense. Unproven tests (or tests proven not to help) cause more harm than good by leading to other invasive unnecessary tests. The informed patient doesn’t want to be screened for “everything”. He wants only what has been proven to help.

Learn more:
Looking For Lung Cancer With A Yearly X-Ray Doesn’t Reduce Deaths (Shots, NPR’s Health Blog)
X-Rays No Help Against Lung Cancer (Wall Street Journal)
Prostate, Lung, Colorectal, and Ovarian Cancer Screening Trial (National Cancer Institute clinical trial page)
Screening by Chest Radiograph and Lung Cancer Mortality (Journal of the American Medical Association)
Spiral CT Scans Save Lives from Lung Cancer (my post about lung cancer screening with CTs)

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Vitamin E Increases Risk of Prostate Cancer

ineffective but harmful

Lots of my patients take vitamin supplements. I don’t recommend them. My patients don’t ask me about it, they just tell me. In the absence of a specific vitamin deficiency or medical condition, there is absolutely no evidence that any vitamin improves any health outcome. I’ve always assumed that vitamins are generally ineffective, but harmless. Some patients are very eager to feel like they’re doing everything they can to be healthy, and I usually decide not to say anything and instead save my credibility for convincing them to exercise or to take their prescription medications as directed. I figure that building trust is better than arguing against their harmless placebo. But maybe I’ve been wrong.

Enthusiasm for vitamins is apparently as deep as the evidence that they don’t help. About twenty years ago antioxidants, including vitamin E, became all the rage, not because we knew them to be helpful, but because what we thought we understood about cell biology suggested that they should be helpful. Since then every rigorous trial has shown vitamin E ineffective in whichever condition it was supposed to help, most recently in preventing heart attack and stroke.

A large trial was started in 2001 to test if vitamin E or selenium might help prevent prostate cancer. Again, there were sound biological reasons to suppose that this might be the case. About 35,000 men were randomized to four groups. One group took 400 units of vitamin E daily. The second took 200 mcg of selenium daily. The third group took both vitamin E and selenium. The last group took placebo. The trial was stopped in 2008 as it became clear that neither selenium nor vitamin E decreased prostate cancer incidence.

But a new study published last week in the Journal of the American Medical Association followed these same men for a few more years and found that the men receiving vitamin E developed prostate cancer significantly more frequently than those receiving placebo. After the longer follow up there were 529 cases of prostate cancer in the placebo group and 620 in the vitamin E group. That means that for about every 100 men taking vitamin E there was one additional case of prostate cancer.

Why? We have no idea. We don’t understand either prostate cancer or vitamin E nearly well enough to understand this effect. But this shows the danger of predicting effects based on our limited understanding of biology. We thought estrogen would prevent heart attacks. It doesn’t. We thought vitamin E would prevent heart attacks. It doesn’t. We thought vitamin E would prevent prostate cancer. It actually slightly increases the risk of prostate cancer.

It’s a good reminder that the only reliable way to have any confidence about the effects of any substance on people is a randomized trial.

So eat a healthy diet. If you’re taking a vitamin for a specific deficiency or medical condition, keep taking it. But if you’re taking it for general health, stop it. There’s no reason to believe it helps, and increasing reason to believe it may hurt. And now when we’re reviewing your medications at your annual exam and you casually mention all the vitamins you take, I might have to gently suggest that you’re doing something risky.

Learn more:

More Evidence Against Vitamin Use (NY Times health blog)

Vitamin E Is Linked to Prostate Cancer (Wall Street Journal)

Vitamin E and the Risk of Prostate Cancer (Journal of the American Medical Association)

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National Panel Advises Against Prostate Cancer Screening

Every year in the US over 200,000 men are newly diagnosed with prostate cancer, and every year 30,000 men die of the disease. With a problem this common that kills so many, you would think that aggressive testing of healthy men is certain to save lives.

Whether screening for prostate cancer has any benefits has always been controversial. By the way, screening means testing for a disease in a patient without any signs or symptoms of the disease. It means testing healthy members of the general population. The test typically used to screen for prostate cancer is a blood test called PSA (prostate specific antigen).

There are three reasons that screening for prostate cancer is particularly problematic. First, it tends to happen in older men. It’s very rare before the age of 50, but three fourths of men older than 85 are found to have it on autopsy. The second reason is that most prostate cancer is very slow growing, and takes over a decade to cause any harm. That means that most men who develop prostate cancer are unlikely to ever be bothered by it and will die of some other cause. So diagnosing those men’s prostate cancer doesn’t help them, but exposes them to all the harms of prostate cancer treatment and all the anxieties related to being a cancer patient. Finally, the PSA is notoriously inaccurate and is frequently abnormal even in the absence of cancer, leading to many negative prostate biopsies.

The national body charged with evaluating which preventive tests are beneficial and which are not is the US Preventive Services Task Force (USPSTF). Three years ago the USPSTF recommended against screening for prostate cancer in men over 75 and said that for men between 50 and 75 there was insufficient evidence to recommend for or against screening. Even the American Cancer Society which represents oncologists (and is therefore about as unbiased about cancer screening as auto mechanics are about regular car tune-ups) last year retracted its unqualified support of prostate cancer screening.

This week in an article in the Annals of Internal Medicine the USPSTF reviewed new evidence and revised its recommendations, recommending against prostate cancer screening in men of any age. The panel concluded that

“prostate-specific antigen–based screening results in small or no reduction in prostate cancer–specific mortality and is associated with harms related to subsequent evaluation and treatments, some of which may be unnecessary.”

Prostate cancer advocacy groups and survivors are already up in arms criticizing the finding, and some are politicizing the issue by claiming that this is an attempt to ration care. But let’s look at the actual data before we pick sides.

Of all the studies to test whether PSA screening saves lives the two biggest and best-designed had conflicting results. One study in the US showed that PSA screening did not save lives. The other, a European trial, found a small benefit. It found that one life was saved from prostate cancer for every 1,410 men checked periodically with a PSA.

So let’s imagine a group of 1,410 men in their 50s and 60s sitting in the local school auditorium trying to decide whether or not to be screened. One study showed that there are no lives saved from screening, in which case there is no reason to do it, but for the sake of argument, let’s accept the findings of the more optimistic trial and agree that testing all of their PSAs periodically will save one of their lives.

What harms will we cause them through screening? Well, first there will be about 12% of them with false-positive PSAs, meaning abnormal PSAs but no cancer. That means 176 of them will be put through biopsies to prove they don’t have cancer. About one of these men will develop a serious complication from the biopsy and require hospitalization.

48 of the men will end up being diagnosed with prostate cancer and will undergo treatment. (But remember only one life will be saved. That’s because the other 47 either die of a cause other than prostate cancer, and thus do not benefit from screening, or died from prostate cancer despite being screened.) Given some reasonable assumptions about the treatments chosen by patients, 36 of them will have a prostatectomy and 12 of them will undergo radiation. That will lead to 14 men having erectile dysfunction and 7 having urinary incontinence. Not to mention that each of the men having prostatectomy have a 1 in 200 chance of dying due to the surgery.

That’s a lot of harm for, at best, very little good, and possibly no good at all. This recommendation should prompt patients and doctors to rethink their opinions about screening and have another conversation about it.

Learn more:

U.S. Panel Says No to Prostate Screening for Healthy Men (New York Times)

Panel Faults Widely Used Prostate-Cancer Test (Wall Street Journal)

Screening for Prostate Cancer: A Review of the Evidence for the U.S. Preventive Services Task Force (Annals of Internal Medicine)

Surgery Might Save Lives in Early Prostate Cancer (my most recent post about prostate cancer with links to previous posts)

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Contagion: the Reality behind the Movie

I’m usually here to remind you not to panic about whatever everyone is panicking about. Early in the H1N1 flu epidemic and in the Fukushima nuclear plant disaster I explained that everything was going to be OK.

But there are some scary germs out there. The 1918 flu pandemic killed between 50 and 100 million people, which at the time was between 3% and 6% of the world population. Ebola virus causes occasional outbreaks of hemorrhagic fever in Africa. It kills two thirds of the people it infects. There is no specific treatment. Hantavirus also causes hemorrhagic fever but is endemic in the US, causing a few dozen cases annually about a quarter of which are fatal. I could go on.

I saw the movie Contagion this week. It’s terrific. I promise I won’t give away any of the plot. The basic premise is the emergence of a novel viral epidemic. The story follows scientists at the Centers for Disease Control and the World Health Organization as they try to isolate the virus, track the epidemic, and find a vaccine, all while the illness rapidly spreads. As far as I could tell everything about the epidemic was entirely realistic. The screenwriters worked with the CDC to learn how pandemics are investigated, and it shows. The movie isn’t terrifying because the devastation is wildly exaggerated as in most apocalyptic fiction. It’s terrifying because it’s restrained and completely plausible.

The CDC’s website has a page about the movie and a page highlighting how their epidemiologists track down new mysterious diseases. Epidemiologists gather information about each patient to figure out if the disease is infectious, how it spreads, and what the incubation period is. Microbiologists isolate the germ, grow it in the lab, and figure out how to prevent, treat or cure the infection. Meanwhile doctors have to use constantly updated information to learn to diagnose and treat new cases, and counsel healthy people on avoiding infection.

The direct effects of a global pandemic would be terrible enough – the many sick and dead. But the societal effects could be even worse. Los Angeles County has a population of about 10 million. Imagine if one percent of them all (that’s one hundred thousand) went to emergency rooms on the same day. There would be pandemonium. The danger from the pandemic would be compounded by the fact that people with even more dangerous conditions like heart attacks or car accidents could not receive prompt care. A recent study of LA County hospital and ER capacity found that in a severe flu pandemic hundreds of thousands of patients presenting to ERs in Los Angeles would not be evaluated due to insufficient capacity. The toll from the disease might be small compared to the harm from the collapse of many basic public services. Civilization might dissolve for a while, and you and your family would need to be self-sufficient.

So as I’ve urged before, make some prudent preparations for a disaster.

And go see Contagion. And wash your hands.

Learn more:

CDC Responds to Contagion

CDC Features: Contagion Movie: Fact and Fiction in Film

CDC′s Disease Detectives: Global Health Sleuths Battle Contagion Worldwide

Contagion (the movie website, and check out the red link at the bottom “learn more about viral pandemics”)

Disaster Preparedness (my post in March)

News Nincompoops Narrate Nuclear Nonsense (my post in March about the Fukushima nuclear plant disaster)

Swine Flu: Unlikely to End the World (my post in 2009 about the new H1N1 flu)

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