Epidemiology

Archive for Epidemiology

Is Ageing a Disease That Can Be Cured?

ageing

There is an ongoing debate that has come to the fore recently about the ultimate limits of human longevity. The ultimate goal of medicine is to optimize health, with the result of maximizing the duration and quality of life. This is accomplished through health promotion, disease prevention, and disease treatment.

There is no question that this approach has increased life expectancy, which is the number of years one can statistically expect to live. The longevity debate is about life span – how long could a human theoretically live if they enjoyed optimal health? What is the ultimate limit of the human biological system?

A recent study by Dong, Milholland, and Vijg concludes that we are already reaching the maximal human lifespan, which they calculate at about 115 years. They looked at two statistical trends. First they looked at the age of the oldest person to die in each country, and found that this age increased from 1970 to 2000, reaching an average of about 115 years. From 2000 to present, however, this figure has peaked, and in fact trended down slightly.

They also looked at the age that had the greatest annual increase in survival. If both life expectancy and lifespan were increasing then this number should be increasing. They found that this number was also increasing from 1920 to about 1980, but then plateaued at around 100 years, and has only slightly crept up since then (101 for men, 102 for women).

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Posted in: Epidemiology

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Infectious Diseases and Cancer

coley

Dr. William Coley. Not a brain surgeon.

With apologies to my colleagues, but infectious diseases really is the most interesting specialty in medicine. There are innumerable interesting associations and interactions of infectious diseases in medicine, history, art, science, and, well, life, the universe and everything. ID is so 42.

A recent email led me to wander the numerous interactions between infections and cancer.

There are the cancers that are caused by infection. HPV and cervical and throat cancer. EBV and lymphoma. HHV8 and Kaposi’s Sarcoma. I certainly hope I am not reincarnated as a Tasmanian Devil. (more…)

Posted in: Basic Science, Cancer, Clinical Trials, Epidemiology, Science and Medicine, Vaccines

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Diet and exercise versus cancer: A science-based view

Exercise time

One of the most effective spin techniques used by advocates of “integrative medicine” (also sometimes called “complementary and alternative medicine,” or CAM for short) to legitimize quackery has been to claim basically all non-pharmacologic, non-surgical interventions as “integrative,” “complementary,” or “alternative.” Thus, science-based interventions such as diet changes to treat and/or prevent disease, exercise, and other lifestyle alterations are portrayed as somehow so special that they need their own specialty, “integrative medicine,” even though they are simply part of medicine. I pointed this out a mere two weeks ago when I discussed the National Center for Complementary and Integrative Health (NCCIH) review of non-pharmacological treatments for pain. It was a systematic review that was essentially negative but spun as positive for some interventions and lacked some key analyses that a good systematic review includes, such as assessment of the quality of the studies included and evaluating them for bias.

Such were my thoughts over the weekend as I got into a Twitter exchange with an advocate of integrative medicine who was touting the benefits of diet as a cancer preventative and how a course in nutrition “opened her eyes.” That in and of itself wasn’t particularly annoying, although I strongly suspect that the nutrition course she took was not given by actual registered dietitians or other experts in science-based nutrition (she wouldn’t say when questioned). What was annoying is that she trotted out some tropes beloved by integrative medicine proponents, such as the claim that most doctors don’t do prevention because they get paid to treat. She was called out for it:

Oddly enough, on the same day a post from the American Society of Clinical Oncology (ASCO) came up in e-mail lists that discussed the actual evidence for the utility of diet and exercise for cancer prevention. It’s almost as though Twitter were telling me it was time for me to discuss this issue from a science-based perspective. So I will attempt to do so.
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Posted in: Cancer, Epidemiology, Nutrition

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Does acetaminophen during pregnancy raise the risk of behaviour problems?

Pregnant1

In my career as a pharmacist I’ve answered a lot of questions about medication use in pregnancy. Pharmacists are among the most accessible health professionals, and we’re usually found near a wall of medicines and supplements.  Many don’t trust Dr. Google, and for good reason: There are conflicting answers online. When it comes to medication use in pregnancy and effects on the fetus, we have no perfect data. Since no-one is randomizing women to drug treatment or placebo, we must rely  on weaker, less definitive evidence. An appropriate response from a health professional will describe known risks and expected benefit, summarizing what we know, and how confident we are in that answer. One of the most popular drugs used in pregnancy is acetaminophen (sometimes called paracetamol or APAP), and commonly known by the brand name Tylenol. An emerging concern with acetaminophen is whether use during pregnancy raises the risk of attention deficit hyperactivity disorder (ADHD) and related behavioural problems. While I covered this question once, back in 2014, there’s a new paper that’s putting this issue back in the news. From Evie Stergiakouli and colleagues is the paper, “Association of Acetaminophen Use During Pregnancy With Behavioral Problems in Childhood: Evidence Against Confounding“, published this week in JAMA Pediatrics. (more…)

Posted in: Epidemiology, Obstetrics & gynecology, Science and Medicine

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Confusing overdiagnosis for an “epidemic” of thyroid cancer in Japan after Fukushima

A Japanese girl being screen for thyroid cancer.

A Japanese girl being screen for thyroid cancer.

One of my favorite topics to blog about for SBM is the topic of overdiagnosis and overtreatment. These are two interrelated phenomena that most people are blissfully unaware of. Unfortunately, I’d also say that the majority of physicians are only marginally more aware than the public about these confounders of screening programs, if even that.

Overdiagnosis has long been appreciated to be a major impediment to translating programs to screen for disease into better outcomes in a number of diseases but has only recently really seeped into the public consciousness, beginning in particular in 2009 when the United States Preventative Services Task Force (USPSTF) issued mammography recommendations that pushed back the recommended age to start screening to 50. Certainly, the concept of overdiagnosis is counterintuitive. After all, why do we screen for disease in asymptomatic people? The reason is simple—and maddeningly intuitive. We screen for disease based on the belief that catching potentially deadly diseases like cancer early, before they produce clinical symptoms, will allow earlier intervention and save lives. It seems blindingly obvious that this should be the case, doesn’t it? Unfortunately, real life biology and pathophysiology aren’t quite so neat and tidy, and the relationship between early detection and improved survival is muddied by phenomena such as lead time bias and the Will Rogers effect, in addition to overdiagnosis.

What is overdiagnosis? In brief, it is the detection of pathology or disease that, if left untreated, would never endanger the life of a patient or even harm him. Note that overdiagnosis is not the same thing as a false positive. A false positive occurs when a test detects disease that isn’t really there; in contrast with overdiagnosis there is definite pathology. The disease being screened for is there, at least in an early form. It’s just that, at the very early stage detected, it’s either not progressive or so indolent that the patient will grow old and die of something else before it would ever cause a problem. Indeed, it’s been estimated that as many as one in three breast cancers detected by mammography in asymptomatic women might be overdiagnosed and that one in five might spontaneously regress. However, because we don’t know which ones are unlikely to cause harm and haven’t worked out a safe method of observing them and intervening if they look as though they are progressing, we are obligated to treat them all when discovered. The problem of overdiagnosis has led to multiple alterations in what once were considered definitive recommendations for screening mammography, first by the USPSTF and most recently by the American Cancer Society.
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Posted in: Cancer, Epidemiology

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Are the recommended childhood vaccine schedules evidence-based?

The vaccine schedule: Safe and efficacious.

The vaccine schedule: Safe and efficacious.

We write about vaccines a lot here at SBM, and for a very good reason. Of all the medical interventions devised by the brains of humans, arguably vaccines have saved more lives and prevented more disability than any other medical treatment. When it comes to infectious disease, vaccination is the ultimate in preventive medicine, at least for diseases for which vaccines can be developed. We also know that when vaccination rates fall, it opens the door for diseases once controlled to come roaring back. We saw this phenomenon with the measles a year ago in the Disneyland measles outbreak. We’ve seen it around the country, with measles outbreaks occurring in areas where a lot of antivaccine and vaccine-averse parents live. Perhaps the most spectacular example occurred in the UK, where prior to Andrew Wakefield’s fraudulent case series in The Lancet that was used to link the MMR vaccine to autism, measles was under control; it came roaring back as MMR uptake plummeted in the wake of the publicity his research engendered. By 2008, ten years after Wakefield’s case series was published, measles was again endemic in the UK. Measles outbreaks flourished. Although MMR uptake is improving again in the UK, there remains a reservoir of unvaccinated children aged 10-16 who can transmit the virus.

Thanks, Andy.

Fortunately, Wakefield has been relegated to sharing the stage with crop circle chasers, New World Order conspiracy theorists, sovereign citizen cranks, and other antivaccine cranks like Sherry Tenpenny. Unfortunately, the damage that he has done lives on and has metastasized all over the developed world. Given the persistence of the antivaccine movement, which fuels concerns about vaccines in parents who are not themselves antivaccine but are predisposed to the antivaccine message because they distrust government and/or big pharma or have a world view that overvalues “naturalness,” I was quite interested in an article that appeared in The BMJ last week. Basically, it asked the question “Is the timing of recommended childhood vaccines evidence based?
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Posted in: Clinical Trials, Epidemiology, Public Health, Vaccines

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Air Pollution and Public Health

airpollution

Public health measures are those not aimed at individuals but at society as a whole, or subgroups within society. Physicians are charged not only with promoting the health of their own patients, but as a profession we (and health care professions in general) are charged with promoting the public health.

Public health measures, however, are highly likely to cross into politically charged areas. This should not deter the promotion of public health.

Issues that we deal with regularly involving public health include vaccination programs and laws surrounding vaccine requirements, fluoridation of public water supplies, helmet laws, and even gun laws. We have never, however, written about air pollution as a public health concern (except for dubious claims that air pollution is linked to autism).

The health risk of air pollution

Air pollution as a health risk is nothing new, but several recent studies are focusing attention on this issue. Recently the Royal College of Physicians produced a report in which they claim that 40,000 deaths per year in the UK can be attributed to poor air quality, both indoors and outdoors. (more…)

Posted in: Epidemiology, Public Health

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Zika virus, microcephaly, and calls to bring back DDT

zika-virus-mosquito

If there’s one thing I’ve learned over the last decade-plus of blogging about medicine and alternative medicine, it’s that any time there is an outbreak or pandemic of infectious disease, there will inevitably follow major conspiracy theories about it. I saw it during the H1N1 pandemic in the 2009-2010 influenza season, the Ebola outbreak in late 2014, and the Disneyland measles outbreak last year, when cranks of many stripes claimed that either the outbreaks themselves were due to conspiracies (usually, but not limited to, conspiracies to promote the “depopulation” vaccination agenda of—who else?—Bill Gates) or that nefarious forces were seizing on the outbreak to take away our freedom. The second thing I’ve learned is that inevitably people will try to impose their ideology on to the disease and try to use outbreaks to push their own ideological agenda. Indeed, the Ebola outbreak, for example, was rapidly seized on by politicians to promote quarantines and to halt immigration from the affected countries. This year, the biggest infectious disease-related story thus far is the Zika virus outbreak in Brazil that has been linked to microcephaly and other birth defects, and it’s a case of the same stuff, different year.

The Zika virus is a mosquito-borne flavivirus related to dengue virus and transmitted primarily by Aedes aegypti mosquitoes. On the surface, this virus would appear to be relatively benign, with 80% of those infected by it remaining asymptomatic, while the other 20% suffer from what is usually a self-limited, relatively mild illness characterized by fever, rash, arthralgias (joint aches), and conjunctivitis. In the grand scheme of things, after decades of being endemic in many tropical areas Zika virus infection probably didn’t seem so bad and didn’t appear to be much of a public health priority in the regions where Aedes aegypti mosquitoes live, mainly tropical regions in South and Central America, Africa, southeast Asia, and the Pacific islands. Then came the evidence that prenatal infection might cause microcephaly, and everything changed. Not surprisingly, conspiracy theories galore arose with social media speed, as did the ideologically motivated overselling of proposed solutions, such as bringing back DDT to combat the mosquito carrying the disease.
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Posted in: Basic Science, Epidemiology, History, Politics and Regulation

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Holding the supplement industry to account: Can we learn from tobacco regulation?

When it comes to supplements, you can't trust what's on the label

When it comes to supplements, you can’t trust what’s on the label

The idea that “natural” products are safe and effective has been so effectively marketed to us that many don’t recognize it as a fallacy. Much of the supplement industry is built around an appeal to nature. Supplements are described as natural, gentle, and “holistic”. Medicine, especially prescription drugs, is the opposite. They’re “chemicals”. They’re risky and dangerous – just look at that list of side effects! Supplements are packaged beautifully, have impressive claims, and are for sale at Whole Foods. Drugs are hazardous: They may come in a plain vial, with warning labels, detailed information sheets, and cautious statements about their effectiveness. Is it any wonder that many consumers, when faced with health concerns or medical issues, instinctively think of supplements as a safer alternative? Purveyors of supplements and alternative medicine have leveraged this fallacy so effectively that it’s even guided the regulations that allow their sale. Regrettably, the result is a marketplace that puts consumers’ interests last. The supplement industry has completely stacked the odds against the consumer, challenging their ability to make informed decisions about their health. Most supplements on the market have never been properly tested for safety or effectiveness. And those that have been tested have largely been shown to be ineffective – or in the case of products like vitamins, often unnecessary. And while there are undoubtedly some ethical companies out there, the industry is regularly revealed to resemble a wretched hive of scum and villainy. Despite this, the industry has gone from success to success – in terms of sales, at least. In 1994 supplement sales were about $4 billion in the US. It’s now a $37 billion industry that is remains only lightly regulated – or largely unregulated. With recent action taken against fraudulent products, there are more questions than ever about how to force the supplement industry to make consumer protection a priority. A new paper in Drug Testing and Analysis makes a provocative suggestion: Local and state governments already regulate another hazardous product: tobacco. Can lessons learned from the tobacco wars improve the safety of supplements? (more…)

Posted in: Epidemiology, Health Fraud, Herbs & Supplements, Politics and Regulation, Public Health

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No, Purell Does Not Breed Super-Anything

Pictured:  Mechanism of pumpy doom, or savior to us all?  Neither!

Pictured: Superbug spawner, or savior to us all? Neither!

Recently, I was sitting in a meeting and reached for the dispenser of Purell hand sanitizer sitting on the conference room table. A colleague of mine gave a small, rueful shake of her head to the person on her other side. Apparently I had erred. I asked what was the matter, and got a brief answer to the effect of “because superbugs.” We exchanged nothing more about it; the interaction was over before the alcohol had dried from my hands.

I wouldn’t have thought anything of such an interaction with anyone else, but my colleague is a PhD student in immunology, six years older and more schooled than I, doing her doctoral research in a lab run by a physician-scientist — a specialist in infectious disease, no less. A touch ironic.

And so I noticed a need for some mythbusting: alcohol-based hand sanitizers do not breed resistant bacteria. (more…)

Posted in: Epidemiology, Evolution, Public Health, Science and Medicine

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