Archive for: October, 2010

Flu Update

Oct 28 2010 Published by under Medicine

Welcome to flu season!  Let's review.

Influenza is a virus that affects humans and several other species that often live in close proximity to humans such as domestic pigs and birds.  The virus changes over time due to "antigenic drift", often rendering immunity to previous strains irrelevant.  If an animal is infected with two strains, they can recombine, leading to a new and very different virus, a process called "antigenic shift" which leads to pandemics.

Influenza is horrible.  It usually strikes hard and fast, with muscle aches, cough, and fever (the usual case definition for influenza-like illness is temperature of 37.8/100.0, cough or sore throat, an no other good explanations for the symptoms).  For most people it will pass, eventually.  For some, it will damage the lungs making them susceptible to bacterial infections like  pneumonia, which can be fatal.

Last season saw the emergence of a new strain if influenza A, now called 2009 A H1N1, probably due to antigenic shift.  It rapidly became pandemic, affecting especially younger people who seemed to have little immunity for the new strain. (Also, pregnant women died at an alarming rate.)  In a normal season, it's the elderly and people with chronic diseases who suffer the worst effects of the epidemic. There is no indication of a looming pandemic this year (although H1N1 will still probably be around), so we're likely to have the usual unpredictable flu season.   Excess deaths due to the flu vary considerably from season to season, with best estimates of between about 3000 and 49000 deaths per year.

Each season, a vaccine is developed by tracking strains emerging in other parts of the world. The vaccine is usually quite effective at preventing flu and complications from flu, but some past seasons have seen new strains emerge after the development of the vaccine.  Vaccination is still the best way to prevent flu.

Anti-viral medications can help reduce the severity of the flu, but they're not terribly effective.  Prevention is the best tool we have, including hand washing and other hygiene, and vaccination.

So far, only minimal flu activity has been seen in the US.  I've seen a few suspicious cases, but nothing confirmed.  Each year is a bit of a surprise.  I've gotten my shot, as has my daughter.  Supplies are good this year.  Hopefully, it will be a boring season.

18 responses so far

Donors Choose (#donorschoose)

Oct 27 2010 Published by under Donors Choose

Guess what?  There's a great project on my list that's less than $50 away from completion.  You guys have been great, but it's been awhile since we funded a project.  remember, even small donations go a very long way ($1-$5 is great).  Thanks in advance.  Let's get this one done, and move on to the next.

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Uncommon suffering

Oct 27 2010 Published by under Medicine

(I'm giving you fair warning: this is a long piece, but I've divided it up for you.  Each part will do fine on its own, but of course I'd like you to read both. You'll be a better person for it. --PalMD)

Part I: Uncommon Sense

Everything was OK until Christmas; before that she felt fine.  Then she began to feel tired.  She was having trouble sleeping so, she thought, maybe that was it.  She tried some sleeping pills from the drugstore, but she still didn't feel right.  Just doing a load of laundry wore her out.  She and her husband normally got together with the same set of friends every New Year's Eve, but this year she was too tired.   She hated New Year's Day, because every year she made another set of resolutions, usually about her weight.  When she got on the scale this year, she was up twenty pounds. Twenty pounds!  Impossible!  Her pants fit more or less the same, although her shoes were tight.  In fact, she'd been wearing unlaced shoes around the house and couldn't really fit into most of her socks.  She went to bed disappointed.

That night she woke out of a sound sleep and sat bolt upright---she couldn't breathe.  She ran to the window, threw it open, and gulped in cold air, slowly feeling better.  Her husband called an ambulance.

Heart failure is a condition in which the heart isn't pumping well enough to meet the body's needs.  Fluid can back up into the lungs, making it hard to breathe, the legs can become  swollen; and depending on the severity, heart failure can lead to sudden death.   One of the mainstays for the treatment of heart failure is a class of medications called diruetics which cause patients to urinate more, decreasing swelling and easing breathing.  But diuretics don't really affect the heart itself, they just drain off fluid, alleviating some symptoms.  It seems logical that if a failing pump is responsible for many of the symptoms of heart failure (and it is), then medications that improve the pumping action would be a good thing, and those that decrease it bad.  It's common sense.  It's intuitive.

Medical students and residents often dread discussions about statistics (a characteristic which I'm sure is not unique to these groups).  And who can blame them, really?  Statistical analysis is inherently non-intuitive.  Its purpose is to separate us from our own natural inclinations to identify patterns (our "intuition") in order to systematically study relationships between variables of interest.

A number of years ago, doctors noted that a certain class of drugs ("inotropes") improved the pumping action of the heart.  Patients with heart failure were given these drugs, and their heart function improved.  Common sense, right?  But when the topic was studied systematically, researchers found that these drugs actually increased mortality.  Oops (in this case, "oops" means people dying).

Another group of drugs called beta-blockers can reduce the pumping action of the heart, and for years were assiduously avoided in heart failure---until study after study showed that beta-blockers actually decrease mortality in chronic heart failure.

Common sense can give us a starting point, but until the big questions are examined systematically, we are in danger of intuiting our patients to death.  Beta blockers are now a mainstay of heart failure treatment, and inotropes a rarely-used footnote, a treatment reserved for a specific set of circumstances.  But we didn't figure that out through common sense alone.

Part II: Does smoking pot cause cancer? Continue Reading »

18 responses so far

Anti-government rhetoric is a threat to public health

Oct 27 2010 Published by under Medicine

Perhaps it will come as no surprise that I find the current surge of anti-government activism sweeping parts of the nation (including this gem) to be problematic.  Thanks to the author, I'm currently enjoying Beating Back the Devil, Maryn McKenna's 2004 book about the founding of the Epidemiology Intelligence Service.  I'm still near the beginning of the book, but one thing that's clear is many of our greatest successes in health have come from---by necessity---government intervention.  The CDC arose out of a wartime agency focused on malaria eradication (when was the last time you caught malaria in the US?), and the EIS (part of the CDC) tracks down emerging public health threats.  When you see a story in the paper about white powder in an envelope, or about an outbreak of dysentery, it's the EIS that is on the scene tracking down threats.

Public health problems are enormous, and leaving them to the private sector is folly.  The resources needed are nearly prohibitive, and corruption such as protection rackets is nearly guaranteed.  Even producing vaccinations---something done by private corporations---requires government support via protections against law suits.

When you take a drink of tap water without fear of typhoid or cholera, when you send your kid to the swimming pool without fear of polio, when you sit on the porch on a spring evening without fear of malaria, you have publicly-provided health programs to thank.

4 responses so far

Donors Choose---time to get back to work (#donorschoose)

Oct 25 2010 Published by under Donors Choose

The Donors Choose challenge that you've been participating in has been doing great.  We've raised a ton of money for projects for needy kids in Michigan (estimated reach this year is over 430 kids).

But the challenge will be over in about two weeks, and some of the projects will be expiring soon.  This one for example, will purchase audiobook equipment.  They need $241 more, and they need it soon.  Maybe we can make these kids happy in the next 18  hours?

One response so far

Broccoli, cancer, and evaluation of risk

Oct 25 2010 Published by under Medicine, Uncategorized

We have some learning to do today, thanks friend of the blog, becca.  The other day, I took issue with a press release published on another website.  It was titled, Discovery may help scientists boost broccoli's cancer-fighting power, which I found to by hyperbolic and deceptive.  The actual study being reported regarded the ability of certain compounds found in cruciferous vegetables such as broccoli to be absorbed from the cecums of rats.  I dismissed the entire piece as being unsupportive of its ambitious headline.

Becca took me to task for being too dismissive:

This is a paragraph from a review article (Keck and Finley, 2004) the manuscript cites:

“Epidemiologic studies have demonstrated inverse associations between crucifer intake and the incidence of lung, pancreas, bladder, prostate, thyroid, skin, stomach, and colon cancer.3 Prospective dietary assessment of 628 men diagnosed with prostate cancer found that increasing crucifer intake from 1 to 3 or more servings per week resulted in a 41% decreased apparent risk.7 A 10-year cohort study of 47,909 men reported that increased crucifer intake, but not fruits and other vegetables, was associated with decreased risk for bladder cancer (relative risk = 0.49, 95% confidence interval = 0.32-0.75, P = .008).6″

Those numbers are simply quite solid evidence, in the context of epidemiology. Is sulphoraphane the only compound in crucifers that is important? Of course not. But this epidemiology *combined* with the cell studies you so blithely write off strongly suggest that the long term goal of the scientist you take issue with “to increase bioavailability of sulphoraphane” is, in fact, a valid pursuit.

Reading and understanding the medical literature is not an art but a skill, one that must be learned.  This learning never ends.  When I run into studies I'm not sure I understand, I can run questions by my colleagues both online and in real life.  For me, it's always work, and I'm happy to be told when I'm wrong. Medical literature can be very different from other scientific literature, as it often focuses on risk, and reported measurements of risk can be quite deceiving (you may have to copy and paste the link address into a search engine).  We also have to look at studies in the context of other studies evaluating similar questions.  Because the results of medical studies often drive changes in practice that affect millions of people, we have to pay close attention to what risk and risk reduction really mean.

For this exercise, we'll focus on the two main assertions quoted by becca (the assertions are from a review article published in a somewhat questionable journal, so separating theses assertions from folklore is particularly important).

Cruciferous Vegetables and Prostate Cancer (Odds ratios are confusing)

Study design is important.  The type of study helps determine how association between two variables can be expressed.

The cited study is a retropective case-control study.  This means that a group of patients with prostate cancer were compared to a group of similar men who did not have known prostate cancer, and they were asked to look back in time and report their intake of cruciferous vegetables over the last five years.  This sort of study is vulnerable to recall bias, in which respondents' memories may not accurately reflect the truth.

Looking at the numbers from Cohen study, comparing the  "most cruciferous eaters" and the "least cruciferous eaters" there is an (adjusted) odds ratio for prostate cancer of  0.59.  You could say that the "broccoli" group had a 41%  decreased odds of having prostate cancer compared to the broccoli-avoiders.  But odds ratios are a tricky statistic and aren't intuitive. For rare diseases, odds ratios are comparable to "relative risk", a more intuitive number.  But for common diseases (and prostate cancer is relatively common), an odds ratio can be deceptive.  That's one of the many reasons a prospective cohort study is more useful in this case, and such a study has been done.

The study cited below by Giovannucci took a sample of tens of thousands of males who were keeping track of their eating habits and at the end of the study period compared the intake records of those who did or did not have prostate cancer.  This significantly stronger study found no significant association between cruciferous vegetable consumption and the risk of developing prostate cancer (although some of the subgroup analyses were tended toward interesting).

Bladder cancer (relative risk and number needed to treat)

In the Michaud study, comparing men who ate the most cruciferous veggies to those who ate the fewest, there was, as stated, a "relative risk" of 0.49.  What does this mean?  It means an absolute difference in risk  for bladder cancer between the two groups of 0.038%.  It also means that to prevent one cancer (number needed to treat) would require 2622 person-days of high-cruciferous diet.  The initial 49% relative risk sounds big, but in real cases, it's not a terribly significant number.

Compared to the prostate data, though, there is evidence from this and other prospective studies that consuming large amounts of cruciferous vegetables may have a small protective effect against the development of bladder cancers.

These subtleties are difficult, and definitely not sexy.  But they are closer to reality.  While it would be reasonable for me to tell patients that the sum of available data indicate that a diet higher in fruits and vegetables is probably healthier than a high-calorie, meat-based diet, there are not sufficient data for me to "prescribe" a high-cauliflower diet to prevent bladder or prostate cancer.  They certainly don't allow us to assume that "broccoli has cancer-fighting power" for us to "boost".  None of the studies looked at the specific use of any compound, just the use of vegetables.

It takes a long time for basic science to move into the clinic---for good reason.

References

Keck, A., & Finley, J. (2004). Cruciferous Vegetables: Cancer Protective Mechanisms of Glucosinolate Hydrolysis Products and Selenium Integrative Cancer Therapies, 3 (1), 5-12 DOI: 10.1177/1534735403261831

Cohen, J. (2000). Fruit and Vegetable Intakes and Prostate Cancer Risk Journal of the National Cancer Institute, 92 (1), 61-68 DOI: 10.1093/jnci/92.1.61

Giovannucci E, Rimm EB, Liu Y, Stampfer MJ, & Willett WC (2003). A prospective study of cruciferous vegetables and prostate cancer. Cancer epidemiology, biomarkers & prevention : a publication of the American Association for Cancer Research, cosponsored by the American Society of Preventive Oncology, 12 (12), 1403-9 PMID: 14693729

Michaud, D., Spiegelman, D., Clinton, S., Rimm, E., Willett, W., & Giovannucci, E. (1999). Fruit and Vegetable Intake and Incidence of Bladder Cancer in a Male Prospective Cohort JNCI Journal of the National Cancer Institute, 91 (7), 605-613 DOI: 10.1093/jnci/91.7.605

Zeegers MP, Goldbohm RA, & van den Brandt PA (2001). Consumption of vegetables and fruits and urothelial cancer incidence: a prospective study. Cancer epidemiology, biomarkers & prevention : a publication of the American Association for Cancer Research, cosponsored by the American Society of Preventive Oncology, 10 (11), 1121-8 PMID: 11700259

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More crappy reporting from LabSpaces

Oct 22 2010 Published by under Journalism, Medicine

LabSpaces, a newer member of the science blogosphere, has some great bloggers.  But as I recently pointed out, they're failing miserably in one domain.  LabSpace's founder Brian Kreuger has an ambitious vision to create a sort of "facebook for scientists" (not his words).  In his words:

LabSpaces.net is a social network for the scientific community designed to spread scientific news, maintain and create friendships, and harbor collaboration through the internet. The site serves as a web profile for researchers and labs, and is also a community for active communication in the sciences.

Included in his vision is, "a Science News feed updated daily with ~40 news articles."  This is where the problem begins.  LabSpaces bloggers do what good science bloggers do, but the "featured article" section is a travesty.  It is an uncritical regurgitation of institutional press releases and other PR documents.  My interest is in proper reporting of medical information, and the articles consistently fail to deliver un-hyped and accurate medical information.  The article that was the subject of my last critique was removed, along with the critical comment threat.  Today he features another miraculous-sounding headline. How does this one measure up? Continue Reading »

62 responses so far

Medical Ethics Friday: Is your doctor on the payroll, and should you care?

Oct 22 2010 Published by under Medical ethics, Medicine

I'm a medicine geek.  I love it.  I love going through cases in detail, developing a differential diagnosis, tossing around ideas with colleagues.  Medicine is great fun.   The professional organization for my specialty is the American College of Physicians, and we had our state chapter meeting recently.  One of the highlights was a session where experts were given difficult cases to solve.  These docs were sharp.  They are all respected clinicians and researchers, usually department or division chiefs.   Watching them work can be very humbling (well, not for them...).

There are no "grades" for doctors; your reputation is whatever your colleagues and patients say it is.  I like to think that these opinions will roughly track with ability.  What is certain, though, is that a real reputation can't be bought.  But that doesn't stop people from trying.

One of the big stories this week was ProPublica's Dollars for Doctors, an investigation into the relationships between pharmaceutical companies and doctors hired to speak for them.  These docs are often touted as experts in their fields.   What ProPublica found (and what is unlikely to surprise many doctors) is that many speakers are not exactly experts, and many are not exactly at the top of their fields.

Speaking for drug companies can be very lucrative.  I've been approached a number of times, and given that even a few speaking engagements per year can significantly supplement the salary of a primary care doc, it's not surprising that many say "yes".

Having a financial relationship with a drug company is not prima facie unethical.   But there are all sorts of ethical pitfalls, some subtle, some not, that emerge from such a relationship.

So, here's a case:

You're sitting at dinner and start to feel some indigestion.  You burp a few times, but aren't getting any better. In fact, you rapidly feel worse, and the "heartburn" starts to make your arm and neck ache.  You start feeling panicked, and are having a little trouble breathing.  Your spouse calls 911 and you're brought to a tertiary care hospital where you are found to be having an "acute coronary syndrome", but not an active heart attack.  The ED docs put you on medications and transfer you to the cardiac unit.  A cardiologist recommends going for an angiogram and possible stent placement in the morning.

Depending on the results of the angiogram, possible solutions to your problem may include coronary artery bypass graft surgery, angioplasty with stent placement (with either a bare metal or drug eluting stent) or medical therapy.  There may be further findings that suggest the need for an implantable device such as a defibrillator or pacemaker.

The cardiologists at the hospital have seen their (substantial) incomes decline significantly over the last couple of years due to a combination of better treatment of heart disease (not as many people need expensive interventions) and cutbacks in what they are paid for diagnostic tests and other procedures.  Some of the docs supplement their income by speaking for drug and device manufacturers.   The department has a national reputation, however, with the cardiologists actively involved in research and publication.

You don't have a lot of time to shop around.

What sorts of ethical problems might be involved here?  Are the doctors' judgments inherently invalid?

Remember some of the basic ethical principles: beneficence, non-maleficence, autonomy, justice.

There are a number of obvious questions here, but also a number of non-obvious problems.  I'd like to hear what you think.

18 responses so far

Donors Choose project needs urgent help (#donorschoose)

Oct 21 2010 Published by under Donors Choose

Reader and Donors Choose booster Jenny just posted this in a comment. I'm elevating it so that hopefully we can help these kids before the clock stops: Continue Reading »

3 responses so far

When did you really feel like a doctor?

Oct 21 2010 Published by under Medical Musings, Medicine

The Doctor, Samuel Luke Fildes (1843-1927)

Yesterday on Twitter, my friend and colleague Dr. Isis noted that she still gets a sense of surprise when she sees "Dr" next to her name in an email.  She, Alex Wild, and I wondered what are the experiences that really make you feel like a doctor (in this case, PhD or medical doctor).  So I started wondering: what are the experiences that made me really feel like a doctor? Was it the white coat ceremony?  Dissecting a cadaver? Wearing scrubs and a stethoscope around my neck?  All of those are important steps, and important memories for me.  But as I thought about it, I was taken back to a particular night in a particular place.

My residency program had a night float rotation.  Three senior residents would be in the hospital from 11pm until 7am (more or less), each covering a different set of patients.  We would run cardiac arrests, admit new patients, and put out various (metaphorical) fires.  And we would pronounce patients dead.  Each of us shared the duty, on a nightly rotation, of covering the inpatient hospice service.  On one of my first night float calls, my pager went off, directing me to call the hospice unit.  They asked me to come down and pronounce someone dead.  I walked down the hall (no hurry, right?), got on an elevator, walked down another hall and into the calm, well-appointed unit, with its gentle lighting, living room couches, aquarium (at least, I think there was an aquarium).  The nurses directed me to a corner room.  The lights were low when I walked in, and a man was laying in the bed.   His color was---wrong.  Everything was wrong.  I walked over and tried to wake him up, shaking him and calling his name.  I took out a penlight and lifted open an eyelid, my fingers resting on his cold, sweaty brow.  His pupils didn't react.  I placed my stethoscope on his chest and watched and listened for a long time.  There were no breath sounds, no heart tones.  He was most certainly dead.  I called the attending physician and the family, waking them both, and sat down to do my part of the "death kit", which included the death certificate.  After a few jests with the nurses, I walked back out into the harsher light of the living.

I'd never felt more like a doctor than I did that night.

6 responses so far

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