Who is public health?

Sarah Mittermaier, Communications Specialist

Sarah Mittermaier, Communications Specialist

Jessica Berthold, Communications Manager

Jessica Berthold, Communications Manager

Ed Note: Please welcome Jessica Berthold and Sarah Mittermaier to the blog today. Jessica Berthold is communications manager, and Sarah Mittermaier is communications specialist, of Prevention Institute (website, twitter), a national nonprofit based in Oakland that works to improve health equity and the community conditions that promote health.


Who do you think of when you think of public health?

Maybe the epidemiologist, the clinic coordinator, the researcher, the program specialist who distributes mosquito nets in malaria-prone countries and pamphlets at health fairs.

But what about the urban planner, the organic farmer, the hospital physician, the policymaker? Public health in 2015 is the block captain, the volunteer tutor and the environmental activist. Public health is anyone who helps make his or her community a healthier, safer, and more just place to live.

We know that health is an issue that shapes everyone’s life experiences, but we’ve been less inclined to see how everyone shapes health—or to realize the extent of various people’s influence in this realm. The urban planner who builds green space and gardens into her design isn’t just creating a more pleasant place to live; she’s creating an environment that fosters healthy eating, active living, and community togetherness. The city block captain who organizes litter cleanups not only makes his street tidier, he builds connections between neighbors and bolsters community well-being by facilitating trusting social networks.

When we think of health, we tend to think of health care first, but people and activities like the ones outlined above create the conditions for health—preventing illness and keeping communities healthy in the first place.

This movement toward an inclusive definition of public health can be seen in the healthcare system, as more physicians, nurses, and administrators become involved in community endeavors. Kaiser Permanente has created dozens of farmers’ markers at or near its hospitals so community members can access fresh, healthy food. At St. John’s Well Child and Family Center in Los Angeles, clinicians have worked with community partners to address substandard housing, after discovering poor living conditions were causing skin disease, rodent bites, and lead poisoning in their patients.

And at Asian Health Services in Oakland’s Chinatown neighborhood, clinicians became concerned about the large numbers of pedestrians brought to the clinic after being hit by cars. Clinic staff convened community members, traffic planners, policymakers, and health agency workers, and found that chaotic traffic patterns contributed to these injuries. Together, this ad hoc coalition worked to reconfigure the red lights and crosswalks to make it safer for pedestrians, and injuries dropped as a result.
Increasingly as a discipline, public health is approaching long-standing issues, such as community violence and chronic disease, from a more holistic perspective that allows us to see the relationships between them, and start working together toward real solutions. We know that people are less likely to be active if their streets and local parks aren’t safe, and that children who are scared at school can’t focus on learning. Violence has a cascading effect on education, physical activity, community trust, and well-being, and ultimately, economic and social opportunity. To change this, we call on nontraditional public health actors like schoolteachers, neighborhood watch groups, libraries, and city parks and recreations departments, to craft solutions together.

In Los Angeles, initiatives like Parks After Dark convert county parks into safe places for community members to play and come together. Violent crime in the neighborhoods surrounding participating parks declined 32% over four years, even as violent crime increased city-wide. In a separate initiative, the Los Angeles Health Department worked with breastfeeding coalitions and healthcare providers to make all county hospitals “baby friendly.”

In Philadelphia, the Mural Arts Program used a grassroots model to engage community members, including ex-gang members, in the creation and painting of murals that helped make disenfranchised neighborhoods safer, more beautiful, welcoming places to live.

The beating heart of public health today lives in projects like these–and the people who make these changes happen by improving the streets we walk, the places we shop, the spaces we play and work in, and our interactions with others. It is inclusive, interconnected, and in many ways, universal.

Who is public health? The real question is, who isn’t?

Category: Epidemiology, Guest Posts, Health systems, Industry, Infectious disease, Maternal health, Nutrition | Tagged , , , , , , , | 4 Comments

Was It Unethical to Hoax the World About Chocolate as a Weight Loss “Accelerator”?

Yes, of course.


Is it somehow more ethical to conduct and publicize a bad study because you honestly don’t know any better? Journals and news outlets are full of small-scale, p-hacked, badly reported studies. This one is a drop in a vast ocean of sloppy science.

The full story is here: a journalist, a doctor, a statistician, and a couple of filmmakers ran and publicized a trial of chocolate on health outcomes, resulting in international headlines about how chocolate is scientifically proven to help you lose weight.

The genius of the plan is that it was “real” science, badly done. Most of the key flaws are ones that, as a journalist, I see crossing my inbox every day:

Only a handful of subjects. The paper didn’t actually say how many, which would have been a major red flag to me; the expose reveals that there were fifteen. With small numbers of subjects, studies don’t have enough statistical power to tell the difference between signal and noise.

P-hacking, or the green jelly bean problem: If you ask 20 questions, and accept answers that would seem to be rarer than a 1-in-20 chance, you’re bound to turn up a bogus result or two. This is a Stats 101 mistake, but it happens far too often. Take this study about ACL injuries in soccer players: “Soccer players are at greatest risk for ACL injury when defending, especially when tackling the opponent in an attempt to win possession of the ball. Females are more likely to injure their ACLs when defending and are at greater risk for noncontact injuries in their left lower extremity.” As far as I can tell, the authors tested 96 different combinations of conditions. (I’m not totally clear on that number, because the section describing their analysis was only two sentences long.) This was probably done naively, but it’s every bit as wrong here as in the chocolate hoax.

Chocolate. Why, oh why, do people keep falling for studies that are about chocolate? And studies that are sort of ostensibly about chocolate but in fact feature a supplement or toothpaste with an extract that shares an ingredient with chocolate, but then they get published alongside stock photo of women posing seductively with chocolate bars? I wrote about the minefield of chocolate-and-health studies here on Lifehacker. Bottom line: a very little science fuels a lot of marketing and wishful thinking.

But Was It Ethical?

Technically no, but I have a hard time believing any substantial harm was done on the journalism/publication side. The millions of people who read a blurb in Shape or the Daily Mail have moved on: the latest on chocolate is that it helps alertness. (Thanks, Hershey.) And even without the recent hoax/expose study, scientists were already feeding magazines headlines about chocolate helping weight loss, like in this Women’s Health article from 2013.

What about the fifteen (originally sixteen) research subjects? Author John Bohannon told Retraction Watch that there was no ethics board involved, which probably violates a variety of principles, laws, and treaties like the Declaration of Helsinki—but the subjects were told they were being filmed for a documentary, which was true. Ethical or not, if approval was required every time people were being manipulated for entertainment, reality TV would never have gotten off the ground.

Could it have been approved? Ethically, there’s always a small risk to participants as a result of participating in a study—breach of privacy, for example. Ethics boards usually want the benefit from the study to outweigh the harms or risks that participants take on. Is that the case here? What’s the benefit of a hoax? It’s hard to say.

The Bright Side

The most hopeful part of the story is the part that hasn’t been told: How many publications didn’t publish news about the fake study? Bohannon says that none of the articles quoted an outside scientist, but that’s not quite how a smart journalist, or editor, works. If a story has a promising headline but is based on sketchy science, you either figure this out yourself by reading the study, or (if you’re still not sure), you contact the outside expert first, before reaching out to the study author. If the outsider trashes the paper, you either report it with that information, or kill the story.

This has happened to me. It’s an awkward conversation when you say to your editor: “Hey, remember that story I convinced you to assign me? Three experts say it’s garbage and I don’t think we should publish it.” (Your contract should ensure that you get a “kill fee” in this case—partial payment to account for the research you did.)

So we don’t know the names of the journalists and publications that didn’t bite on this story. Who knows, I may have been one. I scroll past a lot of overhyped health stories every day.

In the end, although I don’t officially approve, I appreciate this hoax. Because a lot of bad science gets published, and usually the news cycle passes it by, sweeping it into the archives with all the other garbage that managed to glide to publication unquestioned. I wish every bad study came with a “Gotcha!’ post afterward.

Category: Uncategorized | Tagged , , , | Leave a comment

Advice for those considering and those in a PhD

Readers of the blog will know that I successfully defended my PhD in March. Today, I want to share some thoughts I have on the process for those considering a PhD and for those in the PhD.

Deciding if you want to do PhD is an important decision, and not one that should be taken lightly. I get a lot of people asking me whether they should do a PhD, and whether my thoughts have changed since I started. After four and a bit years, I have lots of thoughts. However, if I was to group them, they’d fall into two major categories: those considering a PhD, and those in the PhD.

For those considering a PhD


Good, I have your attention.

Here’s the thing – almost always when someone asks me for advice, they already know they want to go to grad school and want me to validate their decision. They’re not looking for information, they’re looking for confirmation. This is a terrible state of mind to start from and doesn’t serve you well.

What I advise people to do is to start from the point of you don’t want to do it, and convince yourself why you should, even if that’s not where you are in your decision making process. There are two reasons for this. First, knowing why you want to do a PhD will help you tailor your thesis to your career goals. Your project, your extra curricular activities, your training, will all be impacted by where you see yourself going and why. Second, this will help you when you inevitably get stuck in “the valley” and need motivation. If you know this is what you want, and this is why you are here, motivation will be in abundant supply.

Talk to lots of people

Talking to lots of people will give you a good idea of what works for you and what resonates with your own situation, and may help you realize things that are important to you that you never really considered. Ultimately, people prioritize things differently. I’m going to provide my own perspective, fuelled by my experiences, values and beliefs. However, yours may differ. For example, I put a premium on working with specific people, and that weighs heavily on my decision making process. Talk to lots of PhD students, both inside and outside of your target school, and get a feel for what resonates with you and what doesn’t. There are definitely situations where talking to those living those examples would be beneficial and useful, such as if you have kids, are returning to school, or have significant others with their own career. People in the program living those examples can speak candidly about how it impacts their life and any advice they might have. Do not underestimate how effectively the minutiae of daily life will wear you down over time.

For those in a PhD

Death by a thousand paper cuts

One thing about the PhD you’ll hear a lot is that it’s a marathon, not a sprint. This has several important consequences. Working consistently means you’ll never be in a situation where you have to do a bunch of work under pressure. Now, granted, there are still situations where you’ll need to be putting in long hours (running samples, field season etc), but make these the exception, not the rule. You have to keep at it, and keep chipping away.

But this cuts both ways. You have to prepare yourself for 4+ years of study at the start, which means developing good habits in terms of health, sleep, and coping. The same way you can chip away at the PhD in small doses, the PhD will grind you down if you let it. And speaking of that, if you need to seek out help, do it. The PhD is a gruelling process, and taking time to seek out help from counsellors, psychologists, and others can have important consequences for your mental health.

Will it help me finish or will it add time?

This question should be your mantra through grad school. One of the best things about the PhD is the freedom you get. You can come in and leave whenever you want, and there’s lots of freedom to pursue side projects. I’ve seen friends go on and do fascinating and powerful work outside of their PhD because they had the freedom to. However, you have to ask yourself every time you take on new things: will this help me finish or will this add time. Depending on the institution, you may only have funding for a finite period of time, and after that you are on your own, but you’re still paying tuition. If something isn’t going to help you finish, think very carefully about whether or not you want to do it. Be objective and cutthroat. The most precious resource you have is time – make sure you’re investing it wisely.

Know when to fold

One important and not often discussed issue in graduate school is leaving. Sometimes people start a PhD thinking it will go a certain way, and sometimes they realize halfway through this isn’t what they want. If this resonates with you, then consider whether finishing is worth the time investment. This is all highlighted by the sunken cost theory. Once you’ve invested all this time, you don’t want to leave. However, rationally, this might be the right decision for you. Above all, remember that this is an option, and it might be the right one for you. Obviously this isn’t a decision to be made lightly, but remember that this is an option.


That all being said, I enjoyed my PhD experience. I was fortunate to have supervisors and friends who supported me throughout, and I don’t think I would have had the time to pursue my passions and side projects if I wasn’t given the latitude a PhD provides. A PhD can be a great experience, but just be careful and ensure that it is what you want for your career.

Further reading:

  1. Why did you go to graduate school?
  2. What are the things that are important when picking your adviser/PI?
  3. What about your committee?
  4. How have you/do you deal with criticism and rejection; be it from advisers, professors, peers or funding committees?
  5. How did you deal with rejection when you were applying to schools?
  6. Are there tips for fighting impostor syndrome?
  7. What if things aren’t going so well? What advice do you have for those who might having a tough time – either juggling multiple commitments, losing interest or falling behind?
  8. Is doing a Masters and PhD at the same school frowned upon? What about undergrad/Masters/PhD?
  9. What has surprised you so far about the grad school experience? In which cases did it meet your expectations and when did it fail to do so? (i.e. How is graduate school life different to undergraduate life?)
  10. What does it take to be a successful graduate student? Are there any last minute tips/advice/inspirational words you have for budding graduate students?
Category: Epidemiology, Science Outreach | Tagged , , , , , | 3 Comments

The most distinctive causes of death in each US state


The most distinctive cause of death (defined as the location quotient) for each state and the District of Columbia, 2001–2010. The map shows the cause of death from the International Classification of Diseases, 10th Revision (ICD-10), List of 113 Selected Causes of Death with the highest age-adjusted mortality rate ratio in each state. The causes are listed in the legend in the order of disease classification in ICD-10. This map highlights nonstandard cause-of-death certification practices within and between states that can potentially be addressed through education and training.

Often left to the domain of geography, maps are an under-recognised yet essential tool in the field of public health. Public health researchers don’t often make maps, yet they are terribly valuable in public health practice for basic descriptive understanding of the distribution of health and disease states. The US Centers for Disease Control and Prevention (CDC) has recently come out with an interesting and useful new map, which summarizes the ‘most distinctive’ causes of death by US state (1).

What does the map show?

Rather than show a commonplace and easy guessable measure such as the most common causes of death, the CDC authors aimed to present ‘a more nuanced view of mortality variation within the United States’.

Enter the ‘most distinctive’ causes of death by state: causes of death that were significantly more common in a given state than the nation-wide average.

The authors calculated the standardized mortality rate (SMR) ratio for 136 causes of death according to the International Classification of Diseases, 10th revision for the state mortality rate compared with the national mortality rate. The ‘most distinctive’ cause of death for each state was thus calculated, and mapped.

The map speaks for itself. The authors note that some causes of death make sense, such as influenza in some northern states, pneumoconiosis in coal-mining states, and air and water accidents in Alaska and Idaho. They pointed out death by legal intervention in 3 western states as not so apparent, while I found syphilis in Louisiana and inflammatory diseases of female pelvic organs in New York State highly concerning.

The authors also pointed out that the map highlights national variation in how deaths are recorded. Many of the deaths shown on the map are highly rare, and would only take a few code errors in the rare cases that they occur to make them appear statistically significant in this analysis. In any case, this map is an interesting visualisation of public health data that should generate several hypotheses about why it exists the way it does.



Boscoe FP, Pradhan E. The Most Distinctive Causes of Death by State, 2001–2010. Prev Chronic Dis 2015;12:140395. DOI: http://dx.doi.org/10.5888/pcd12.140395

Category: Determinants of health, Epidemiology, Health systems | Tagged , , , , | Leave a comment

What I Learned About Health From Reporting It

Photo by Jeremy Bronson  https://www.flickr.com/photos/jbrons/5216172956

Photo by Jeremy Bronson.

Some people find themselves nodding along with articles like 25 Struggles Only People Addicted to Diet Coke Will Understand. Me, I got that same feeling from reading this Vox piece by Julia Belluz and Sarah Kliff: No more dieting, and 7 other things we do differently after reporting on health care.

I’d like to add a few more things to the list based on my own experience writing about health. But first, the top nodding-along items on the Vox list:

Dieting (#1 on their list): Despite the fads, science hasn’t consistently found any one diet to be better than others for weight loss. But here’s the kicker: none of them work in the long term. Measured on a scale of years (rather than weeks or months), dieting tends to leave people heavier than when they started. You’re better off eating and exercising for health, which works even if your weight doesn’t budge.

Screening (#7 on their list): If you go looking for problems, you just might find ones that aren’t really there. Screening tests have risks as well as benefits, and making a healthy person go through cancer treatment for a harmless “incidentaloma” is a pretty awful fate. I don’t turn down every sort of test, but I do choose carefully.

New Studies (#2 on their list): Work the news cycle long enough, and things stop feeling like news. Another superfood? Yawn. Another potential new antibiotic? Put it over there with all the others that haven’t worked out. I love studies that bust a long-held myth, but I almost never take the bait anymore. A single study tells us very little. Now, a Cochrane review that concludes a long-held myth is dead? That I’ll pitch.

Here are a few things I’ve learned that weren’t on the Vox list.

Trust guidelines, but only so far. The best recommendations are evidence-based, and can do a world of good. For example, new guidelines recommend more IUDs and less cervical cancer screening. But guidelines are measures meant for public health, and may not apply to you, in particular, as an individual. Sometimes, guidelines simply aren’t based on good quality evidence. And health care providers may be relying on outdated guidelines even when the evidence (and newer guidelines!) prove those old guidelines wrong.

News always comes from somewhere. Just as butterflies come from caterpillars, so do health news stories come from press releases. Savvy readers and reporters know to check for Big Pharma funding a study on, say, a drug—but how many of us look for a funder or publicist on a study that reports on how eggs make your salad healthier? Well, guess what: that study was funded by the American Egg Board. Plenty of studies on antioxidants in fruit are on cranberries, because Ocean Spray funds a lot of scientific research. That doesn’t mean that other fruits don’t have health benefits, but we hear more about cranberries than those others because the cranberry promoters fund and publicize more research. It’s a type of publication bias that affects the public without most of us ever knowing.

Category: Uncategorized | Tagged , , , , , , , | 1 Comment

Level up! Mr Epid is now Dr Epid!

My old lab got me a cake to celebrate!

My old lab got me a cake to celebrate!

I’m back! I took an extended hiatus from the blog while I finished up my PhD, but, at the end of March, I successfully defended my PhD, and after making the changes suggested by the examining committee I submitted in the middle of April and started working. Those of you following along on Twitter will recognize the change in my Twitter handle from @MrEpid to @DrEpid; those of you who know me in real life will have heard me go on about it for the last few months as I prepare. For those wondering, I will eventually change the URL of my blog as well so they all match :)

For those unaware of the process, the PhD defence is an oral exam. At Queen’s (the process may differ at other universities), you submit your thesis, and then have to wait (a minimum) of 25 business days for the exam. The exam consists of 4 examiners; an examiner external to your university, one external to your department, one from your department, and the final examiner is your department head (or a department head delegate). You also have a chair from another department from your institution, as well as your supervisors there. After you give a 15-20 minute presentation, the examiners ask their questions. Typically, there are two rounds of questions, after which you leave, and the examiners deliberate. You’re then called back in, and they let you know their decision, and any changes you have to make before submitting your final thesis. My examiners were amazing, and while the questions were tough, they were fair. I actually really enjoyed the discussion I had with my examiners during my defence, and they ranged from the details of my analysis, to the concept of “ethnic identity” and what it actually means in terms of my research.

I want to thank everyone for their support over the past 4 and a bit years. As per prior precedents (Janiszewski, 2010; Saunders, 2013), I will be copy-pasting the acknowledgements section from my thesis below. I’d also like to thank the PLOS Blogs network, especially Victoria Costello for giving me the opportunity to join the network, and Travis and Peter for their support and encouragement when I started blogging. In addition, thank you to my co-authors Beth and Lindsay here who picked up the slack when I took a hiatus this year to focus on finishing up.

Finally, a special thank you to all the readers of the blog. It’s been a privilege to write for you, and it means a lot when you tell me how much you enjoy my work. Thank you, and I’m looking forward to getting back into writing more regularly.


I would like to start by thanking my supervisors, Dr. Will Pickett and Dr. Ian Janssen. I am grateful to have had the opportunity to learn from you both, and appreciate your support through my PhD journey. Your honesty, integrity, and willingness to always provide me feedback and support was always appreciated. Will, I look forward to our teams meeting in the playoffs again (hopefully with better results for me this time!)

I would also like to thank those in the Department of Community Health and Epidemiology/Public Health Sciences and the Clinical Research Centre for their support, with a special thank you to Lee Watkins and Deb Emerton for their help. Thank you also to the Clinical Research Centre Student Group. Your antics, customized t-shirts, snack breaks, and random dance parties always kept me entertained, and it’s been a pleasure working with all of you. The Thought Tub is richer for having you.

This work would not have been possible without the financial support of Queen’s University, the Ministry of Colleges, Training and Universities Ontario Graduate Scholarship, and the Canadian Institutes of Health Research Frederick Banting and Charles Best Canada Graduate Scholarships Doctoral Award.

I would also like to thank my friends and colleagues, especially Anne, Kim, Raymond, Sarah, Alison, Hidé and Marion who have been unwavering in their support over the years. I also owe a special debt of gratitude to Rim, Lydia, Liam, Hoefel, Brian and the Gong Show/Danger Zone family for ensuring that I always get some physical activity, and that yes, I do even lift.

Finally, thank you to my family. Your love, support, guidance, and willingness to listen to me at all times of the day have allowed me to complete this project. Thank you.

Category: Admin, Epidemiology | Tagged , , , | 2 Comments

The ‘autism epidemic': increasing cases or increasing diagnoses?

Increase_in_autism_diagnosis (1)

“Increase in autism diagnosis” by fightingautism.org – Licensed under Public Domain via Wikimedia Commons

 An interesting new study was recently published in the British Medical Journal about the ‘autism epidemic’ we have been experiencing in recent years (1). The Swedish authors of the study used data from children born between 1993 and 2002 to compare time trends in the rates of the autism symptom phenotype (i.e. the symptoms upon which a diagnosis of autism is based) and registered clinical diagnoses of autism spectrum disorder.

Why was this study done?

The prevalence of autism has jumped dramatically since about the 1970s. A review of U.S. studies found that prevalence increased 10-fold between the 1970s and 1990s, from less than 3 cases per 10,000 children to over 30 cases per 10,000 children (2). The U.S. CDC also found rising cases throughout the 1990s, but that prevalence has actually declined between 2000 and 2010 (3,4).

The reasons for this ‘autism epidemic’ are controversial. The falsified autism-vaccine link received torrid media coverage over the past decade, causing a sharp drop in childhood vaccination rates and subsequent rise in measles among children (5). Other potential causes are thought to be environmental, given that the human genome is stable over a 30-40 year period. If some secular environmental exposure is causing increased rates of autism, then it would be a major public health crisis.

Bucking this ‘environmental causes’ line of thought, the authors of the current study hypothesised that the ‘autism epidemic’ may be due to how autism has been diagnosed and registered over time. They provide four reasons for this hypothesis:

  • The rise in prevalence was reported during the same time period that the diagnostic criteria widened;
  • Increasing awareness of autism spectrum disorder causes ‘diagnostic substitution’: when children who would have previously been diagnosed with a learning disability or other mental illness or retardation are now diagnosed with autism;
  • Patient referral and availability of services increases due to increasing awareness; and,
  • Differential availability of case records and the way in which cases are diagnosed between similar geographical regions leads to wide variation in measured and actual prevalence.

What did they do?

Data from the Swedish national patient register on over 1 million Swedish children born between 1993 and 2002 were used. The register contains data on registered, diagnosed cases of autism spectrum disorder based on ICD-9 and ICD-10 codes (international classification of diseases, 9th and 10th revisions).

The comparison data came from the Child and Adolescent Twin Study in Sweden (1). The twins’ parents were interviewed over the telephone, using the ‘Autism-Tics, ADHD, and other Comorbidities’ (CATSS) inventory, which is designed to be administered by a layperson over the telephone to assess symptoms of autism spectrum disorder, including language and communication, social interaction, and restricted and repetitive behaviours (1). It is independent of the interviewer’s clinical knowledge or preferences, does not disclose which symptoms belong to which disorder, and evaluates lifetime symptoms. Hence, it should remove the biases listed by the authors in their hypotheses about the ‘autism epidemic’ (1).

The prevalence of registered diagnosed cases in the general population of Swedish children was compared to the prevalence of autism symptoms in the Child and Adolescent Twin Study over a ten-year period.

What did they find?


Annual prevalence of autism spectrum disorder in Child and Adolescent Twin Study in Sweden (CATSS), national patient register (NPR), and NPR diagnoses in Swedish twins. *Prevalence calculated on 19 993 people responding in twin study born 1993-2002. †Prevalence calculated on all twins, irrespective of response in CATTS (n=26 953). Diagnosis in NPR was ascribed before the children’s 10th birthday. ‡Prevalence calculated on all births in Sweden 1993-2002 (n=1 078 975). Diagnosis in NPR was ascribed before the children’s 10th birthday. Regression lines are depicted within 95% confidence intervals. Reproduced from (1).

In the Swedish national patient register, the authors found that the population prevalence of autism spectrum disorder was 0.42%, ranging from 0.23% to 0.60% at different time points (1). They observed a linear increase in prevalence over the ten-year period (P for trend <0.0001). By contrast, the population prevalence of autism symptom phenotype was 0.95%, ranging from 0.52% to 1.59% at different time points (1). This prevalence was stable over time (P for trend = 0.85).

The key point to note is that, while there were no significant differences in the prevalences of diagnosed autism spectrum disorder and autism symptom phenotype, the prevalence of the former (diagnosed cases) steadily increased with time, while the prevalence of the latter (undiagnosed symptoms) was stable with time.

What do the results mean?

The study authors concluded that their data do not support a secular increase in the rate of autism spectrum phenotype, meaning that the way in which autism cases are diagnosed and recorded may explain the rising cases of autism observed over recent decades (1). These results should be good news, as they do not indicate that a secular environmental exposure accounts for a large proportion of new autism cases in recent times. However, the findings from the study are likely to be taken as controversial by anti-vaccine supporters. Hopefully, this kind of research can be translated effectively into the public domain to improve public awareness and knowledge. More research from other geographical locations such as the United States testing the same hypotheses as in this study would also be valuable.



  1. Lundström S, Reichenberg A, Anckarsäter H, Lichtenstein P, GillbergAutism phenotype versus registered diagnosis in Swedish children: prevalence trends over 10 years in general population samples. BMJ 2015;350:h1961.
  2. Blaxill MF. What’s going on? The question of time trends in autism. Public Health Rep 2004;119:536-51.
  3. Yeargin-Allsop M, Rice C, Karapurkar T, Doernberg N, Boyle C, Murphy C. Prevalence of autism in a US metropolitan area. JAMA 2003;289(1):49-55.
  4. Centers for Disease Control and Prevention. Autism Spectrum Disorder (ASD): Data and Statistics. http://www.cdc.gov/ncbddd/autism/data.html (accessed 06 May 2015).
  5. Centers for Disease Control and Prevention. Measles cases in the United States reach 20-year high. http://www.cdc.gov/media/releases/2014/p0529-measles.html (accessed 06 May 2015).
Category: Epidemiology, Health systems, Time trends | Tagged , , , , | 7 Comments

When a Company Drops a Controversial Ingredient, They’re Not Doing It For Your Health

This week, Pepsi announced they were dropping aspartame from their flagship diet drink in the US.

Last week it was Chipotle swearing off GMO ingredients.

Before that, Kraft dropped certain dyes, Subway took the “yoga mat chemical” out of its bread, Gatorade stopped using brominated vegetable oil, and these are just a few of the dubiously health-related but loudly trumpeted food reformulations of recent years.

Companies reformulate their products all the time, but when they make a big announcement about the change, I’m skeptical that it’s anything other than a marketing move (or a swap they were going to make anyway, with a convenient reason). It turns out there are reasons, not exactly hidden, to question the do-good intentions of recent reformulations.

Diet Pepsi

I wrote today at Lifehacker about the science behind Pepsi’s shift away from aspartame. Short version: there’s no reason to believe that aspartame is dangerous, and people who want to err on the side of caution won’t find the replacement sweeteners any more reassuring.

But Pepsi acknowledged that although they were bowing to consumer concerns about safety, they didn’t believe the sweetener was unsafe. Sure, it makes sense that a company would be careful not to state that they’d been knowingly poisoning customers (even if that were true). But their actions suggest that health concerns are a red herring:

  • Pepsi’s CEO discussed the shift as part of a conference in which he also explained that sales have been lagging and a nod to consumer demand is part of the strategy to bring sales up.
  • Pepsi is only changing the formula for Diet Pepsi and two variations on the drink, and only in the US. Meanwhile, Diet Mountain Dew and Pepsi Max will keep their aspartame, because consumers aren’t complaining specifically about aspartame in those drinks.


Dropping GMO ingredients from the Chipotle menu, likewise, can’t be based on any serious health concerns. Dan Charles at NPR explains some of the reasons why the move is hypocritical:

  • They’re keeping sodas, which often include GMO corn syrup.
  • They’re keeping sodas, which have actual known health risks much larger and more definite than any of the suspected health risks of GMO products.
  • They cite concerns about the pesticide resistance in farming practices associated with GMO soy plants, but are switching away from soy to an oil that, while non-GMO, has very similar pesticide concerns.

It looks like Chipotle is making the switch simply because consumers want it, and it’s easy. They’re only changing two ingredients: Cooking oil, and corn flour tortillas. If GMO corn and soy were sprinkled across their menu, would they be as committed to the change?

The bottom line

While giving in to consumer pressure may help a company’s bottom line, the implication that it’s for health reasons (which is usually not stated outright because, you know, it’s usually not based in science) may be a bad thing for scientific understanding among the public. The likes of the #FoodBabeArmy get their concerns addressed without any reference to the actual science involved. (The Food Babe’s first objection to Kraft’s yellow dye? It’s made from petroleum. No, that’s not the same as eating asphalt or gasoline. Sorry.)

I understand wanting to change ingredients, but that can happen without a media splash. The neon-colored dyes in Kraft products kind of gross me out too, especially next to the grayish color of the noodles. I’m not concerned for my kids’ health, but as I stir the cup (on the days we’ve bought Kraft’s brand instead of Annie’s–both end up in our kitchen), I wonder who decided cheese should be this color anyway? And the truth: It was probably because, years ago, consumers liked it better that way.

Category: Uncategorized | Leave a comment

Why Isn’t Sex Ed Preparing Students for Adulthood?

Uterus Anatomy Embroidery Hoop Art Wall Decor in Orange

When I was in high school, I took a class that taught me how to dissect a worm. We were not expected to go home and dissect worms or somehow put to use our newly found expertise on worm anatomy. Still, I remember that dissection teaching me ideas and skills I used later on: How to carefully cut something open and learn about its insides; why exactly a worm is shaped the way it is; the similarities between worms and humans (we both have hearts! Sort of).

In another class, I learned how to write a check and balance a checkbook. I didn’t have a bank account in my name at the time, but the information stuck.

Algebra felt useless at first, but gave me the tools I needed to crunch numbers in later classes like physics and population genetics.

So why, when we talk about sex ed classes for teenagers, do we focus on what students will do with the information they learn right now​? A conservative arguing for abstinence-only education, or a more evidence-minded person talking about which type of sex ed “works” better, are only focusing on immediate outcomes: Do kids go home and have sex? If they do, are they getting pregnant or contracting STDs?

Imagine if we set curricula this way for all subjects: Choose the content for math classes based on the math we expect kids to do in their daily life. Pare down art curricula so that kids won’t be able to use what they learn in making graffiti.

Or, more shockingly, imagine that we taught sex ed with the same goals as academic subjects: Preparing students for life after high school.

Even in the fantasy world where students never have sex while they’re young enough to still be taking sex ed classes, almost all will have sex later on. They’ll need to know about consent and pleasure and risks. Many will need to know about fertility and how pregnancy works.

What happens then?

It turns out they might remember what they learned in sex ed, and that’s not a good thing. Take this 2012 study by Chelsea Polis and Laurie Zabin of Johns Hopkins. They found that 19% of young women and 13% of young men believed they were infertile. Those numbers are far higher than the actual prevalence of infertility in that age group, which means there could be a significant chunk of sexually active young people who believe, incorrectly, that they can’t get pregnant. Here’s the likely reason why:

Polis and Zabin point out that some public health messages designed to encourage consistent contraceptive use focus on the fact that pregnancy can occur after a single act of unprotected intercourse and do not adequately explain the probability of pregnancy.

…an oversimplified message may inadvertently lead some individuals to assume they are infertile if pregnancy does not occur after one or several acts of unprotected sex, and may result in reduced motivation to use contraceptives. [quote from the study’s press release]

Focusing on the actual statistics involved in pregnancy would help young people understand their fertility. They also need enough information to understand the real risk of pregnancy from different contraceptives. (Not “condoms fail all the time” but how often do they fail with perfect and with typical use, and how do you achieve perfect use?) A few lucky women might stumble across a copy of Taking Charge of Your Fertility, but why isn’t a basic understanding of the human reproductive system standard issue?

I recently taught a nutrition course to a group of students fresh out of high school. When we got to the part about pregnancy and infant nutrition, they asked some honest questions that made me back up and start from the basics: for example, they weren’t clear on what the beginnings of pregnancy have to do with a woman’s monthly cycle. The 40-week accounting of a 38-week pregnancy was unfathomable to them, because they didn’t realize there was this thing called ovulation that happens two weeks into the cycle. They didn’t realize that when you get pregnant, there’s a lag of several weeks before you’re even able to test for pregnancy. And like I was taught years ago, they thought it was possible for a woman to become pregnant at any time in her cycle. (Possible, perhaps, but extremely rare—and focusing on that possibility means ignoring the biology of how the cycle typically works.)

Along the same lines, kids also need real information and statistics on types of contraceptives, including how to choose one when you need it. So what if they don’t need it right away? They don’t need algebra right now either. But someday they’ll be using math to program the next Angry Birds, and someday they’ll be using their knowledge of contraceptives to decide whether or not to use condoms that night, or whether they should be asking their doc for an IUD.

We have national debates on how best to scare teens away from sex, and sometimes step back enough to debate whether we should scare teens away from sex. But there’s a bigger question we’re missing: what happens when those teens grow up?

Category: Uncategorized | Tagged , , , , , , , | Leave a comment

An ‘apple a day’ keeps the prescription medications away?



Last week, a research article titled “Association between apple consumption and physician visits: appealing the conventional wisdom than an apple a day keeps the doctor away” was published online in the journal JAMA Internal Medicine. A great premise for a health research study, albeit the long research title. The article is written up in a clever, straightforward way – the authors propose, that,

“Although some may jest, considering the relatively low cost of apples (currently $1.13 per pound of Red Delicious apples), a prescription for apple consumption could potentially reduce national health care spending if the aphorism holds true.”

What did they do?

The article presents the results of a classic epidemiological study – a cross-sectional analysis of the U.S. National Health and Nutrition Examination Survey (NHANES). NHANES is a long-running nationally-representative survey of civilian, non-institutionalised American adults. The survey is conducted every few years, when a new random sample of the population is drawn. The authors of the study pooled together respondents from the 2007-08 and 2008-09 rounds of the survey, to get an eligible sample of 12,755 survey respondents (1). From there, they used data from 24-hour dietary recall questionnaires, demographics, health examinations, and health questionnaires completed by the survey respondents (1). After accounting for missing data, excluding all survey respondents who reported that their 24-hour diet questionnaire that they filled out was not representative of their usual diet, and those whose apple consumption came solely from apple juice and apple sauce, the study included 8,399 study participants (1).

The researchers estimated the total grams of raw apple consumed by each study participant during the 24-hour dietary recall period, by linking the reported foods to the U.S. Environmental Protection Agency’s Food Commodity Intake Database (1). They defined study participants as ‘apple eaters’ if the daily amount of apple they reported eating was equivalent to 149 grams (1 small apple). They investigated whether there could be a dose-response relationship between apple consumption and avoidance of health care visits by comparing the effect of eating 1 small vs. 1 medium vs. 1 large apple per day against eating no daily apples.

“Keeping the doctor away” was defined as successfully avoiding more than one visit to a physician in the past year. One physician visit was allowed, as American adults are recommended to visit their doctor each year for an annual health check-up.

What did they find?

The researchers estimated that 19.3 million U.S. adults are ‘apple eaters’, who consume about 26.9 million small apples daily, weighing 8.8 million pounds (1). In contrast, 207.2 million adults were estimated to be non-apple eaters – the majority of the population. Apple eaters were no more likely to avoid visiting the doctor than non-apple eaters (Odds Ratio = 1.19; 95% Confidence Interval: 0.93-1.53), regardless of the size of the daily apple (p-value for trend = 0.06). There was also no difference in overnight hospital stays or mental health visits between apple eaters and non-apple eaters. However, people who ate a daily apple seemed more likely to avoid taking prescription medications than non-apple eaters. When comparing ‘small’ and ‘large’ apple eaters against non-eaters, there were no differences in medication-taking, as the odds ratios were of small (but positive) magnitude and the 95% confidence intervals were wide, indicating imprecise estimates due to small sample size. However, the odds ratio for ‘medium’ apple eaters was positive and statistically significant for avoiding taking prescription medications, and the overall trend in the dose-response relationship between size of daily apple and odds of avoiding medications was statistically significant (p-value for trend = 0.02). Trend analyses, while reliant on p-values, are useful in small sample size situations where a linear dose-response relationship is plausible, as they indicate the overall relationship across categories of exposure (a.k.a. size of apple).



What does it mean?

Although there are limitations of this study – think of all the possible ways in which apple eaters could differ from non-apple eaters, that might also affect whether they might take prescription medications or not (aside from age, sex, race/ethnicity, education, body mass index, smoking status, and health insurance type, which were accounted for). Unmeasured and subsequently uncontrolled confounding in studies like this can always skew results. The study authors propose a prospective or experimental design for the future, to help reduce the likelihood of residual confounding and establish the correct temporality of the relationship – that apple eating comes before not taking medications, and not the other way around. Based on their results, the authors suggest an update of the well-known aphorism to be,

“If anything, apple eating may help keep the pharmacist away.”

It doesn’t quite roll off the tongue, but certainly gets one thinking about how and why these aphorisms come into use in the first place.



1) Davis MA, Bynum JPW, Sirovich BE. Association between apple consumption and physician visits: appealing the conventional wisdom than an apple a day keeps the doctor away. JAMA Intern Med 2015; doi: 10.1001/jamainternmed.2014.5466

Image sources

Fuji Apples: By Scott Bauer, USDA ARS [Public domain], via Wikimedia Commons

Prozac Pills: By Tom Varco (Own Work) [CC BY-SA 3.0 (http://creativecommons.org/licenses/by-sa/3.0)], via Wikimedia Commons

Related Posts Plugin for WordPress, Blogger...
Category: Epidemiology | Tagged , , , | Leave a comment