Archive for Science and Medicine
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.
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!
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.
Several weeks ago I wrote the first in a brief series of posts discussing the different types of evidence used in medicine. In that post I discussed the role of correlation in determining cause and effect.
In this post I will discuss the basic features of an experimental study, which can sere as a check-list in evaluating the quality of a clinical trial.
Medical studies can be divided into two main categories – pre-clinical or basic science studies, and clinical studies. Basic science studies involve looking at how parts of the biological system work and how they can be manipulated. They typically involve so-called in vitro studies (literally in glass) – using test tubes, petri dishes, genetic sequencers, etc. Or they can involve animal studies.
Clinical trials involve people. They are further divided into two main categories – observational studies and experimental studies. I will be discussing experimental studies in this post – studies in which an intervention is done to study subjects. Observational studies, on the other hand, look at what is happening or what has happened in the world, but does not involve any intervention.
A common theme in alternative medicine is the “One True Cause of All Disease”. Aside from the pitiable naivete, it’s implausible that “acidic diet”, liver flukes, colonic debris, the Lyme spirochete, or any other problem—real or imagined—can cause “all disease” (in addition to the fact that most of these ideas are intrinsically mutually exclusive).
One of the popular new ideas in this category is that of “endocrine disrupting chemicals” (EDCs). These are chemicals in the environment that physiologically or chemically mimic naturally occurring human hormones. That some environmental substances are chemically similar to human hormones is indisputable. That these substances can have a real physiologic effect in vitro seems to hold up. How much of an effect these chemicals may have in real human populations is an open question.
Lose weight without diet or exercise? I guess that leaves cancer.
It is the day after Thanksgiving, and I have probably eaten enough calories to support the average family for at least three days. I am hesitant to comment on what my actual weight may be, but others have not been so reticent about discussing my appearance over at RDCT. At least I am not female; then I would get no end of critiques based on my looks.
Now that I am up a few holiday pounds, it would be nice to lose some weight. Of course I do not want to do it the old fashioned way, with diet and exercise. Diet and exercise take time and are fundamentally painful. I want to eat what I want when I want from the comfort of my Lazy Boy. I want an easy way to lose weight. The interwebs, as is often the case, have been kind enough to provide me with numerous emails suggesting all sorts of simple ways to alter my physique for the better, some of which even include weight loss.
While doctor visits for influenza-like illnesses seem to be trending downward again, and ”swine flu” is becoming old news, I’d like to draw attention to an H1N1 story that has received very little coverage by the mainstream media.
Doctors in several states can now protect their most vulnerable patients from the H1N1 virus without worrying about breaking the law. In order to save lives, several states have announced emergency waivers of their own inane public health laws, which ban the use of thimerosal-containing vaccines for pregnant women and young children.
Legislators in California, New York, Illinois, Missouri, Iowa, Delaware, and Washington state have enacted these science-ignoring laws in response to pressures from the anti-vaccine lobby and fear-struck constituents. Except for minor differences, each state’s law is essentially the same, so I will focus on the one from my state of New York.
New York State Public Health Law §2112 became effective on July 1, 2008. It prohibits the administration of vaccines containing more than trace amounts of thimerosal to woman who know they are pregnant, and to children under the age of 3. The term “trace amounts” is defined by this law as 0.625 micrograms of mercury per 0.25 mL dose of influenza vaccine for children under 3, or 0.5 micrograms per 0.5 mL dose of all other vaccines for children under 3 and pregnant women. Because thimerosal (and thus, mercury) exists only in multi-dose vials of the influenza vaccines (both seasonal and novel H1N1), this law really only applies to these vaccines. The mercury concentration of the influenza vaccines is 25 micrograms per 0.5 mL, which therefore makes their use illegal. Unfortunately, the only form of the H1N1 vaccine initially distributed, and that could be used for young children and pregnant women, was the thimerosal-containing form. The thimerosal-free vaccine was the last to ship, and in low supply, and the nasal spray is a live-virus vaccine, not approved for use in pregnancy or children under 2. That meant, without a waiver of the thimerosal ban, these groups could not be vaccinated.
Two weeks ago, Canadian Skeptics United published on their Skeptic North site a piece by an Ontario pharmacist criticizing a proposal by the province to grant limited prescribing rights to naturopaths. The essay, which was reprinted in the National Post on Tuesday, outlines the intellectual and practical conundrum presented by allowing those with education that diverges from science-based practices to prescribe drugs.
The naturopath lobby came out in force and was relatively unopposed in the 54 comments that followed, primarily because the NP closes comments 24 hours after online posting. Therefore, those with a more rational and considered viewpoint based in facts were locked out from commenting. This is quite disappointing to me personally and professionally because of the wildly emotional appeals, strawman arguments, and smears and attacks on the author himself without, of course, addressing his well-founded criticism of the prescribing proposal before the provincial government.
At the Skeptic North post, the piece even drew a naturopath who equated the criticism of his/her field with the Nazis and Mussolini. However, you can’t write critiques of these practices without attracting attacks ad hominem, especially Godwin’s Law, that are the resort of those whose arguments are logically flawed.
I am just a parent with some questions about vaccine safety and was happy to find your website. I have noticed that the Scandinavian countries do not routinely recommend HepB vaccination unless the mother is a known carrier. I did not see this addressed anywhere on your website and I hope you or one of your colleagues might consider discussing the reasons that some advanced countries are not routinely giving this particular vaccine. Thank you.”
Vaccination is a complicated and at times confusing topic that generates a large number of quite reasonable questions by parents like the one above. At the same time, the ever-wandering aim of the anti-vaccinationist movement appears once again to be falling on the vaccine against Hepatitis B, and I’ve heard them pose this very question with the intent of sowing doubt in the current vaccination schedule. Regardless of the source, this question is clearly on the mind of some parents, and I am happy to answer it.
As usual, this question has quite a bit to parse out. I think it may be most helpful to examine why we vaccinate against Hepatitis B the way we do in the US, how most countries in the world approach the problem, and finally examine the reason why eight European countries do not universally vaccinate against HBV. First things first though: what is Hepatitis B?