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Archive for 2009

Radiation from medical imaging and cancer risk

ResearchBlogging.orgScience-based medicine consists of a balancing of risks and benefits for various interventions. This is sometimes a difficult topic for the lay public to understand, and sometimes physicians even forget it. My anecdotal experience suggests that probably surgeons are usually more aware of this basic fact because our interventions generally involve taking sharp objects to people’s bodies and using steel to remove or rearrange parts of people’s anatomy for (hopefully) therapeutic effect. Ditto oncologists, who prescribe highly toxic substances to treat cancer, the idea being that these substances are more toxic to the cancer than they are to the patient. Often they are only marginally more toxic to the cancer than to the patient. However, if there’s one area where even physicians tend to forget that there is potential risk involved, it’s the area of diagnostic tests, in particular radiological diagnostic tests, such as X-rays, fluoroscopy, computed tomography (CT) scans, and the variety of ever more powerful diagnostic studies that have proliferated over since CT scans first entered medical practice in the 1970s. Since then, the crude images that the first CT scans produced have evolved, thanks to technology and ever greater computing power, to breathtaking three dimensional-views of the internal organs. Indeed, just since I finished medical school back in the late 1980s, I’m continually amazed at what these new imaging modalities can accomplish.

The downside of these imaging modalities is that most of them require the use of X-rays to produce their images. True, over the last 15 years or so MRI, which uses very strong magnetic fields and radiofrequency radiation rather than ionizing radiation to produce its images, has become increasingly prevalent. MRI is great because it produces more contrast between different kinds of soft tissue than CT scans do. However, CT tends to be superior for examining calcified organs, such as bone. (The breast surgeon in me notes that breast MRI is pretty much useless for detecting microcalcifications, an important possible indicator for cancer.) Also, MRI scans require a prolonged period of laying still in a very tight tube, which is a problem for patients with any degree of claustrophobia, although “open” MRIs are becoming increasingly available. More importantly for the quality of images, because they require a patient to lie more still than a CT, MRIs tend to be prone to more motion artifacts, which is perhaps why CT is more frequently used to image the abdomen other than large solid organs such as the liver. The point is that, although MRI is becoming more prevalent, CT scans aren’t going away any time soon. They have different strengths and weaknesses as imaging modalities and are therefore best suited for different, albeit overlapping, sets of indications.
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Posted in: Cancer, Public Health

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Measles

It looks like the H1N1 pandemic is fading fast. I am amazed at how lucky we were, at least in the hospitals where I work. A month ago all the ICU beds were full, most of the ventilators were in use and we were wondering how we were going to triage the next batch of patients who needed advanced life support and we had none to offer. Then, right as we reached maximum capacity and had no more wiggle room, the rates plummeted. We skated right up to the edge of the precipice, looked down, and did not have to jump.

The pandemic has not been as bad as expected, but it was still no walk in the park. Nationwide H1N1 killed maybe 10,000, with 1,100 in children and 7,500 among young adults (ref). Oregon has had 1200 hospitalizations and 68 deaths. We had about 8 deaths from H1N1 in my hospital system. We would have had twice that number, but one of our hospitals is a trauma center and offers ECMO (Extra Corporeal Membrane Oxygenation) and we managed to save a number of people who would have died if they had been in a lesser hospital. The national statistics mirror our experience. None of the deaths were in the elderly. Pity the vaccine was slow to be produced as it could have prevented the majority of those deaths.

Are we done with H1N1? Will it become part of seasonal flu? Will it have a third comeback, fueled by holiday travel? Will it mutate and increase virulence? Will it recombine with avian flu to generate a new strain? Is this THE pandemic that comes every 30 years or so, and we will not see another until after I am long dead?

How am I supposed to know? I can’t see the future. Or can I? Mr. Randi, listen up: I am thinking I will be eligible for that million dollar prize. I am receiving future information from the Large Hadron Collider, curiously delivered inside a baguette. I think I can predict the next infection to sweep the US.

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Posted in: Science and Medicine, Vaccines

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Are the benefits of breastfeeding oversold?

As a mother, I am a passionate advocate of breastfeeding and I breastfed my four children. As a clinician, though, I need to be mindful not to counsel patients based on my personal preferences, but rather based on the scientific evidence. While breastfeeding has indisputable advantages, the medical advantages are quite small. Many current efforts to promote breastfeeding, while well meaning, overstate the benefits of breastfeeding and distorts the risks of not breastfeeding, particularly in regard to longterm benefits.

As Joan Wolf explains in an article entitled Is Breast Really Best? Risk and Total Motherhood in the National Breastfeeding Awareness Campaign:

… Medical journals are replete with contradictory conclusions about the impact of breast-feeding: for every study linking it to better health, another finds it to be irrelevant, weakly significant, or inextricably tied to other unmeasured or unmeasurable factors. While many of these investigations describe a correlation between breast-feeding and more desirable outcomes, the notion that breast-feeding itself contributes to better health is far less certain, and this is a crucial distinction that breast-feeding proponents have consistently elided. If current research is a weak justification for public health recommendations, it is all the more so for a risk-based message that generates and then profits from the anxieties of soon-to-be and new mothers…

Wolf describes the problems with many studies of breastfeeding, particularly those that focus on long term outcomes:

In breast-feeding studies, potential confounding makes it difficult to isolate the protective powers of breast milk itself or to rule out the possibility that something associated with breast-feeding is responsible for the benefits attributed to breast milk. As the number of years between breastfeeding and the measured health outcome grows, so too does the list of possibly influential factors, which means that the challenge is magnifiedwhen trying to evaluate long-term benefits of breastfeeding… Breast-feeding, in other words, cannot be distinguished from the decision to breast-feed, which, irrespective of socioeconomic status or education,could represent an orientation toward parenting that is itself likely to have a positive impact on children’s health. In instances such as this, in which the exposure (breast-feeding) and confounder (behavior) are likely to be very highly correlated, confounding is especially difficult to detect. When behavior associated with breast-feeding has the potential to explain much of the statistical advantage attributed to breast milk, the scientific claim that breast-feeding confers health benefits … needs to be reexamined.

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Posted in: Nutrition, Obstetrics & gynecology

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Communicating with the Locked-In

The primary reason that I and others favor science-based medicine, as opposed to the alternatives, is that science works. As Carl Sagan said, “Science delivers the good.” Science has other virtues – it is transparent and self-corrective also.

Recently two unrelated news items have provided an opportunity to compare a scientific vs a pseudoscientific approach to the same problem – that of communicating to patients who are locked-in.

Locked-in describes those who suffer from an injury or neurological disease that mostly paralyzes them, so that they cannot move or communicate. One scenario that leads to a locked-in state is a brainstem stroke, where patients are paralyzed below the eyes – they can only blink and move their eyes, but nothing else. Widespread trauma can lead to a similar situation. ALS, which leads to progressive loss of motor neurons, can also result in total or near total paralysis.

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Posted in: Neuroscience/Mental Health

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The One True Cause of All Disease

Note: This is a slightly modified version of an article that was published in the magazine Skeptical Inquirer, Volume 34, No. 1, January/Februrary 2010. It is reprinted here with the kind permission of the Committee for Skeptical Inquiry.

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Chiropractors, homeopaths, naturopaths, acupuncturists, and other alternative medicine practitioners constantly criticize mainstream medicine for “only treating the symptoms,” while alternative medicine allegedly treats “the underlying causes” of disease.

Nope. Not true. Exactly backwards. Think about it. When you go to a doctor with a fever, does he just treat the symptom? No, he tries to figure out what’s causing the fever and if it’s pneumonia, he identifies which microbe is responsible and gives you the right drugs to treat that particular infection. If you have abdominal pain, does the doctor just give you narcotics to treat the symptom of pain? No, he tries to figure out what’s causing the pain and if he determines you have acute appendicitis he operates to remove your appendix.

I guess what they’re trying to say is that something must have been wrong in the first place to allow the disease to develop. But they don’t have any better insight into what that something might be than scientific medicine does. All they have is wild, imaginative guesses. And they all disagree with one another. The chiropractor says if your spine is in proper alignment you can’t get sick. Acupuncturists talk about the proper flow of qi through the meridians. Energy medicine practitioners talk about disturbances in energy fields. Nutrition faddists claim that people who eat right won’t get sick. None of them can produce any evidence to support those claims. No alternative medicine has been scientifically shown to prevent disease or to cure it. If it had, it would have been incorporated into conventional medicine and would no longer be “alternative.”

Are these practitioners treating the underlying cause, or are they simply applying their one chosen tool to treat everything? Chiropractors treat every patient with chiropractic adjustments. What if a doctor used one treatment for everything? You have pneumonia? Here’s some penicillin. You have a broken leg? Here’s some penicillin. You have diabetes? Here’s some penicillin. Acupuncturists only know to stick needles in people. Homeopaths only know to give out ridiculously high dilutions that amount to nothing but water. Therapeutic touch practitioners only know to smooth out the wrinkles in imaginary energy fields. They are not trying to determine any underlying cause: they are just using one treatment indiscriminately. (more…)

Posted in: General

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Acupuncture, the P-Value Fallacy, and Honesty

Credibility alert: the following post contains assertions and speculations by yours truly that are subject to, er, different interpretations by those who actually know what the hell they’re talking about when it comes to statistics. With hat in hand, I thank reader BKsea for calling attention to some of them. I have changed some of the wording—competently, I hope—so as not to poison the minds of less wary readers, but my original faux pas are immortalized in BKsea’s comment.

Lies, Damned Lies, and…

A few days ago my colleague, Dr. Harriet Hall, posted an article about acupuncture treatment for chronic prostatitis/chronic pelvic pain syndrome. She discussed a study that had been performed in Malaysia and reported in the American Journal of Medicine. According to the investigators,

After 10 weeks of treatment, acupuncture proved almost twice as likely as sham treatment to improve CP/CPPS symptoms. Participants receiving acupuncture were 2.4-fold more likely to experience long-term benefit than were participants receiving sham acupuncture.

The primary endpoint was to be “a 6-point decrease in NIH-CSPI total score from baseline to week 10.” At week 10, 32 of 44 subjects (73%) in the acupuncture group had experienced such a decrease, compared to 21 of 45 subjects (47%) in the sham acupuncture group. Although the authors didn’t report these statistics per se, a simple “two-proportion Z-test” (Minitab) yields the following:

Sample X   N   Sample p

1            32  44   0.727273

2           21  45   0.466667

Difference = p (1) – p (2)

Estimate for difference: 0.260606

95% CI for difference: (0.0642303, 0.456982)

Test for difference = 0 (vs not = 0): Z = 2.60 P-Value = 0.009

Fisher’s exact test: P-Value = 0.017

Wow! A P-value of 0.009! That’s some serious statistical significance. Even Fisher’s more conservative “exact test” is substantially less than the 0.05 that we’ve come to associate with “rejecting the null hypothesis,” which in this case is that there was no difference in the proportion of subjects who had experienced a 6-point decrease in NIH-CSPI scores at 10 weeks. Surely there is a big difference between getting “real” acupuncture and getting sham acupuncture if you’ve got chronic prostatitis/chronic pelvic pain syndrome, and this study proves it!

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Posted in: Acupuncture, Clinical Trials, Science and Medicine

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Another wrinkle to the USPSTF mammogram guidelines kerfuffle: What about African-American women?

A while back I wrote about rethinking how we screen for breast cancer using mammography. Basically, the USPSTF, an independent panel of physicians and health experts that makes nonbinding recommendations for the government on various health issues, reevaluated the evidence for routine screening mammography and concluded that for women at normal risk for breast cancer, mammography before age 50 should not be recommended routinely and should be ordered on an individualized basis, and that routine formalized breast self-examination (BSE) should also not be routinely recommended. In addition, for women over 50, it was recommended that they undergo mammography every other year, rather than every year. These recommendations were based on a review of the literature, including newer studies.

To say that these new recommendations caused a firestorm in the breast cancer world is an understatement. The USPSTF was accused of misogyny; opponents of health care reform leapt on them as evidence that President Obama really is preparing “death panels”; and HHS secretary Kathleen Sebelius couldn’t run away from the guidelines fast enough. Meanwhile, a society I belong to (the American Society of Breast Surgeons) issued a press release accusing the USPSTF of sending us back to the “pre-mammography” days when, presumably women only found breast cancer after it had grown to huge size (just like Europe and Canada, I guess, given that the recommendations for screening there closely mirrors those recommended by the USPSTF). Meanwhile, in the most blatant example of protecting its turf I’ve seen in a very long time, the American College of Radiology went full mental jacket with a press release that was as biased as it was insulting. Meanwhile some physicians even likened the recommendations to going back to being like Africa, Southeast Asia and China as far as breast screening goes in that he actually speculated that he’d now become very busy treating advanced, neglected breast cancers. Unfortunately, as Val pointed out, the communication of the USPSTF guidelines to the public was almost a perfect case study in how not to do it. Even though the science was in general sound and the USPSTF recommendations were in essence close to identical to what other industrialized nations do, they were communicated in just such a way as to produce maximum misunderstanding and misuse for political purposes.

Despite all the hysterical and in some cases disingenuous attacks on the new guidelines, there is one criticism that actually resonates with me because I work at a cancer center in a very urban environment with a large population of African-American women. Last week I heard on NPR this story:
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Posted in: Cancer, Clinical Trials, Public Health

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Cell phones and cancer again, or: Oh, no! My cell phone’s going to give me cancer! (revisited)

ResearchBlogging.orgIt’s been about a year and a half since I’ve written about this topic; so I thought I’d better update the disclaimer that I wrote at the beginning:

Before I start into the meat of this post, I feel the need to emphasize, as strongly as I can, four things:

  1. I do not receive any funding from the telecommunications industry in general, or wireless phone companies in particular. None at all. In other words, I’m not in the pocket of “big mobile” any more than I am in the pocket of big pharma.
  2. I don’t own any stock in telecommunications companies, other than as parts of mutual funds in which my retirement funds are invested that purchase shares in many, many different companies, some of which may or may not be telecommunications companies.
  3. None of my friends or family work for cell phone companies.
  4. I don’t have a dog in this hunt. I really don’t.

There. That’s better. Hopefully that will, as it did last time, serve as a shield against the “shill” argument, which is among the frequent accusations I hear whenever I venture into this particular topic area. So, as I did back in 2008, I just thought I’d clear that up right away in order (hopefully) to preempt any similar comments after this post. Unfortunately, as I have known for a long time, I’m sure someone will probably show his or her lack of reading comprehension and post one of those very criticisms of me. It’s almost inevitable, either here or elsewhere. Posting such disclaimers never seems to work against the “pharma shill” gambit when I write about vaccines or dubious cancer cures. Even so, even after nearly ten years involved in skepticism and promoting science-based medicine, hope still springs eternal.

There are two reasons that I think the issue of mobile phones and cancer needs an update on our blog: First, it has been a year and a half since I last wrote about it. At that time I castigated Dr. Ronald B. Herberman, who at that time was director of the University of Pittsburgh Cancer Institute for what I viewed as fear mongering over cell phones and cancer based on at best flimsy evidence. Second, there have been two fairly high profile studies looking at whether there is a link between mobile phone use and cancer. One of these our fearless leader Steve Novella has already discussed, but there was another one that he didn’t see because it didn’t get quite as much publicity, possibly because the corresponding author is based in Korea. I will take this opportunity to discuss them both.
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Posted in: Cancer, Clinical Trials, Public Health

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The End of Chiropractic

An article written by 3 chiropractors and a PhD in physical education and published on December 2, 2009 in the journal Chiropractic and Osteopathy may have sounded the death knell for chiropractic.

The chiropractic subluxation is the essential basis of chiropractic theory. A true subluxation is a partial dislocation: chiropractors originally believed bones were actually out of place. When x-rays proved this was not true, they were forced to re-define the chiropractic subluxation as “a complex of functional and/or structural and/or pathological articular changes that compromise neural integrity and may influence organ system function and general health.” Yet most chiropractors are still telling patients their spine is out of alignment and they are going to fix it. Early chiropractors believed that 100% of disease was caused by subluxation. Today most chiropractors still claim that subluxations cause interference with the nervous system, leading to suboptimal health and causing disease.

What’s the evidence? In the 114 years since chiropractic began, the existence of chiropractic subluxations has never been objectively demonstrated. They have never been shown to cause interference with the nervous system. They have never been shown to cause disease. Critics of chiropractic have been pointing this out for decades, but now chiropractors themselves have come to the same conclusion. (more…)

Posted in: Chiropractic

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An Influenza Recap: The End of the Second Wave

We are nearing the end of the second wave of the 2009 H1N1 pandemic, and are now a few months out from the release of the vaccine directed against it.  Two topics have dominated the conversation: the safety of the 2009 H1N1 influenza vaccine, and the actual severity of the 2009 H1N1 infection.  Considering the amount of attention SBM has paid the pandemic and its surrounding issues, and in light of a couple of studies just released, it seems time for an update.

2009 H1N1 Vaccine Safety

This week the CDC released a report that evaluated the safety record of the 2009 H1N1 vaccine.  The first two months of the vaccine’s use were examined, from October 1st through November 24th using data from two of the larger surveillance systems monitoring the 2009 H1N1 vaccine’s safety: the Vaccine Adverse Event Reporting System (VAERS) and the Vaccine Safety Datalink (VSD).  This report represents the largest, and to date best, evaluation of the 2009 H1N1 vaccine’s safety profile since its initial testing and release.  The findings are reassuring.

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Posted in: Science and Medicine, Science and the Media, Vaccines

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