Sunday, March 2, 2014

Breastfeeding: the Sibling (study)

The study is here: 

Background:  I'm a Bayesian -- I feel strongly that an analysis of the foundation of evidence on which a study rests and what the prior probability of a claim is fundamental to evaluating the claim.
Therefore, here's a brief analysis of the prior studies:
It is well accepted that breastfeeding is important in developing countries and premature infants because of the decreased risk of necrotizing enterocolitis and diarrheal illnesses [citation left as an exercise to the reader.]  

However, although breastfeeding is extremely culturally emphasized with the "breast is best" mantra and the "babyfriendly" hospital initiative restricting access to formula, the prior literature showed little support for a clinically significant impact of breastfeeding on term infants in the developed world.  In addition, it was strongly suspected that the majority of effect in published studies was related to the association bias.  These facts are absolutely necessary to know in determining how likely you are to find the Colen, et al. study to be valid.  Therefore, I include here a limited literature review to emphasize the point.  (It is also important to note that benefits of breastfeeding have also been exaggerated by the publication bias: i.e. negative studies are unlikely to be published, especially given the current breastfeeding politics.)

  • Intelligence: Studies consistently support an effect of breastfeeding on intelligence.  This effect is consistently so small as to be likely considered trivial to the average person.  For instance, Erikson, et al. found that breastfeeding has the same effect on intelligence as the sex difference, less effect than irregular breakfast and would not have had a significant p-value had the authors used a Bonferroni correction. (!po=46.4286)  The extremely hyped study last summer in JAMA pediatrics ( found the effect size to be 0.35 verbal IQ and 0.29 nonverbal IQ points per month breastfed. This is considered to be the premiere study on intelligence and breastfeeding.
  • Asthma: The evidence is very limited.  The currently most cited study is, which finds that infants who are exclusively breastfed for 2 months or more are less likely to wheeze by preschool age, but equally likely to go on to develop asthma and infants who are exclusively breastfed and then supplemented are more likely to wheeze than those who transition to formula and the effect size and the p-values both are not very significant.  Nonetheless, there are several, similar quality studies making the same claim.  Plausible to have a very small effect.
  • Obesity:  The "it study" is this Japanese study, which showed that among 7-8 year olds, only 7-8% of those exclusively breastfed for up to 6 months were overweight (with 7% at 6-7 months, and 8% for 2 months), compared to 9% of formula fed children and 1.5-2.9% obese vs. 3.5-3.9% obese.  However, a randomized control trial of pro-breastfeeding interventions that succeeded in substantially increasing breastfeeding in the intervention group did not find any difference in weight
So, in summary, in starting the study there is some evidence of a very small positive effect of breastfeeding in reducing asthma and obesity and increasing intelligence.  This effect is statistically small and clinically small and may be completely accounted for by sociodemographic differences.

Introduction:  What does this study add?  The goal of this study is to use paired sibling controls to eliminate sociodemographic differences from consideration as a potential confounding factor.  

  • The study chose to look at 11 outcomes: BMI, obesity, asthma, hyperactivity, attachment, compliance, math ability, memory ability, vocab, reading comprehension and "scholastic competence"
  • Subjects were recruited between ages 4-14 in 13 waves over a 24-year period 
  • Results such as obesity and asthma were coded at the age that they developed 
  • Information was gathered through maternal and child interviews
  • There were 4,071 families (8,237 children) recruited
    • 3,153 families in the sibling cohort (7,319 children)
    • 665 families in the discordant sibling cohort (1773 children)
  • sibling was defined as sharing the same mother
  • Breastfeeding was binary: any breastfeeding v. no breastfeeding
  • The following confounding variables were measured: survey year, maternal age at time of birth, patient age, ethnicity, marital status, region of the country, maternal education at time of interview and birth, income at time of birth and interview, maternal employment at time of birth and interview and insurance (private, public v. none), birth order, preterm status, smoking during pregnancy, alcohol during pregnancy, and prenatal care in the first trimester
It's worth noting in their demographic data that this is old and therefore, only 10-11% of women worked full time in the year after their child was born and a whopping 30-31% smoked during pregnancy -- so probably demographically very different than the modern woman.

Beyond that side note, it is notable that in the discordant sibling sample, there is slightly higher percentage of woman of color, slightly lower educational attainment (12.5 mo v. 13) and slightly lower income (62k v. 68k at time of birth)

 When they compare outcomes between breast and bottlefed infants, they find large benefits in breastfeeding in their intelligence, behavior and obesity measures, which is almost completely nullified, and in some cases even reversed by evaluating paired siblings.  After this step, no statistically significant differences are seen

What this study adds most importantly is it validates the strongly suspected hypothesis that differences between breast and bottlefed infants were largely accounted for by confounding variables.  

The major limitations are worth noting; however,
Exclusivity: The very loose criteria for being "breastfed" was simply having received any breastmilk.  It could be argued that there is a subpopulation of breastfed children who breastfed for longer/higher percentage of nutrition who performed better and are buried in the sample.
Rarity of discordance: I would argue that discordant breastfeeding among siblings is rare and a woman who formula feeds one or more of her children is likely not representative of the average breastfeeding mother.  We can speculate that they are more likely to supplement, and the formula fed child is more likely to be higher in the birth order, which gives them an intelligence and behavior advantage, thus confounding the results.  This can also be seen in that the discordant group was relatively disadvantaged to begin with, so even less likely to have been exclusively formula fed and possibly subject to more effect from other environmental factors.  

Friday, August 12, 2011

How to Teach

In our orientation to becoming senior residents, we were talking about how to teach. It's common for a lot of residents to feel like teaching is a burden -- teaching less experienced residents and medical students is essentially an additional job and our primary job is pretty much all-consuming. Therefore, I wanted to share a couple of tricks, especially for new interns, about what I've learned about teaching in the last year (especially teaching medical students)

1. Probably the biggest point about teaching is that you DON'T need to be an expert to teach. Lots of interns still feel very inexperienced and diffident. It's normal to feel threatened by teaching. It's normal to feel scared about what will happen if a medical student asks you a question and you don't know how to answer. There's two prongs to addressing these fears:
A) As an intern, you have really learned a lot in the last year/year and a half of training that you have compared to a medical student. Think back to when you were a third year, just starting rotations. Everything was new. Even if you don't know a lot about a topic, what you have to say is valuable to a medical student
B) It's totally okay to be honest about your limitations. If a medical student asks me a question I don't know the answer to, I usually encourage them to look it up and let me know. Everyone learns by looking things up and that's a really healthy habit to get into. I don't think of it as me being an inferior teacher by resorting to having the med student look it up (or looking it up with them), I think of it as me teaching them how to learn.

2. Time. Time is the perennial enemy of the resident. The secret is that teaching doesn't need to take a lot of time -- if you're clever about it, you can even net time from teaching.
A) Make your limitations clear. If I don't have a lot of time to teach, I make it really clear how much time I do have by saying things like: "let's talk about asthma for five minutes" or "here's the five things that are really important to know about Kawasaki disease." This makes the discussion feel complete, rather than rushed. If there are questions I can't answer due to time, I treat that limitation the same way I treat my knowledge limitations -- encouraging the student to seek some answers on their own and regroup with me later.
B) Remember how much you learn by doing. People feel guilty making medical students do work. That's a really, really silly attitude. Most medical students realize that the currency in which they get paid is teaching and the currency with which they pay is by doing work. Even with that transaction aside, medical students are not just there to learn the academic side of medicine; they are there to learn the practical side of medicine. Have a ton of orders to write that's keeping you from teaching? Awesome! Medical students need to learn how to write orders. They also need to learn how to examine patients, talk to nurses, write prescriptions, call outside labs to check on results, call consults and the million other day to day things that make intern's lives hectic. I'll be honest -- it usually does take me more time to teach the medical student how to do these things than to do everything myself, but it doesn't take THAT much more time and I don't feel guilty for ignoring my student.

3. "But I don't know WHAT to teach!" or "I don't know HOW to teach!" It's unfortunate, but we're never really taught how to teach well. Not as medical students and not as residents. But it's not that different from anything else you teach yourself how to do: you learn it by doing it over and over, watching what mistakes you make and trying new things until you get it right. For me, a lot of how I learned to ad lib teach was by creating a couple short teaching talks that I could give and giving those over and over until I felt confident. I learned how the would go, solicited feedback on them from the med students and perfected them. If I'm stressed out or intimidated, I still go back to them. It works best if they're things that are common, so that they're likely to be relevant to one of your patients, likely to be something you know well and likely to be something the student will use again.
For peds, I think the newborn exam is perfect. It's fast, easy to teach, easy to teach while you're getting work done (like admitting a newborn), something all pediatric residents know well and something that's usually totally new to students.

4. Teaching repays you. Besides being fun, making you feel like you've contributed to the next generation of doctors and helping you recruit med student minions to help get your work done, I think the biggest benefit of teaching is how much you learn by doing it. Medical students ask questions I never would have thought of and by having them look it up for me (or looking it up with them), I've learned things I never would have on my own. But even more importantly, by spending my time thinking about how to boil down topics to a few essential points to make them quick and easy to teach, it really helps me remember things.

Wednesday, August 10, 2011

More Stuff I Learned

The emergency department (and life in general) has kept me really busy lately, but here's some stuff I learned recently:
1. Syphilis can be painful, despite medical school teaching that it isn't (luckily, I didn't learn this from personal experience!) Chancroid and lymphogranuloma venerum are the two leading differentials for painful genital ulcers, but both are unusual in the United States.
2. Appendicitis has a largely heritable component. Courtney asked me in conversation why some people get appendicitis and others don't. Lit review shows that about 50% of the variability is explained by genetic factors. Who knew?
3. Although MRSA is not a major player in causing otitis, it should be covered when treating mastoiditis

In other news, I found out that I'd been knitting in the round WRONG for the last 10 years. Apparently, you hold the needles close to you and the cables away from you!

Monday, August 8, 2011

How to talk to teens

I had a really frustrating experience in the ED the other day.

I needed a urine specimen from a teenager. Everything had been ordered and I was busy dealing with an actual emergency (it does happen sometimes!) when the nurse came up to me and told me that the patient was refusing to provide a urine specimen and she needed me to talk to the patient.

So I went in to the room and said "I heard you had some questions about the urine specimen. What questions can I answer for you?" The teenager refused to even make eye contact with me. The mother said "She doesn't want to pee in a cup."

"Okay..." I responded, a little confused for how the mom became the spokesperson for this decision. I addressed the teenager again "can you tell me why not?"

She shrugged, but neither her nor her mother proffered an answer. I was a little frustrated, but it also seemed like no one had tried the common sense response so far, so I decided to go for it. "I think that you probably think that it's gross to pee in a cup. To be honest, I know it's weird and it feels strange. Unfortunately, I need for you to do it so that I can make sure you're healthy, so not providing a urine specimen isn't a choice right now. The choices are that you can pee in a bed pan, you can pee directly into a cup or you can pee in a hat (a thing you place on the toilet to catch urine.) If you don't like any of those options, we can use a bladder catheter, which is a tube that we put into your bladder through your urethra. Those are the only choices I can offer you right now. Do you have any questions?"

She now made eye contact. I held my gaze steady. I was pretty willing to be the adult in this circumstance. She shook her head. "OK. Do you have a preference?" She shook her head again. "OK, I'll have the nurse come in and show you the hat and the bed pan and you can choose."

She peed in a bed pan.

The demographic in the emergency department is always a little different. A lot of times we have parents who just don't know how to tell kids that certain things aren't options. Certainly, not all parents are this way (and in the particular case that this is based on the parent was a great parent, who was just at the end of her rope for reasons that weren't relevant to the story.) I was pretty impressed by how easily I reached consensus on what was going to happen. Sometimes, it just takes firmness and explaining what is and is not up for discussion.

Saturday, July 23, 2011

Quiet Call Day

Today's been really a quiet day. One of the things that I love about being on call in the NICU (OK, I just generically love the NICU) is that there's bedside nurses for all of the patients. If I want the nurse, I can just walk to the bedside and talk to her (there's about four male nurses in a cohort of several hundred NICU nurses and none of them are working today.) This is great for collaborating with the nurses on the plans, and also just creates a really nice work environment. I know most of their names (on my side of the NICU there's two residents, about 5 NPs and probably 75 plus nurses; I try to know all of their names, but it's hard.) They all know me. If I want something, I can go and talk to them face to face, without needing to call or page to find them. I walk around every 4 hours, or so, to check in and it goes quickly and I feel involved and in the loop and like a good doctor.

Most floors aren't like this -- most floors some nurses change at 7am and some at 11am and some at 3pm and some at 7pm and some at midnight and it's hard to know which nurse has whom and if you can't find the nurse, there's a million places where s/he might be. It's harder to be a team.

Since it was so quiet, I was chatting a lot with the nurses, mostly about them and their lives, but also about being on call and what it's like. The fact of the matter is that I like my life with call a lot more than any of the alternatives. I like that for a total of 28 hours, I'm really the doctor for these babies (I have a fellow and an attending, but they're mostly only involved when I call them.)

And there's an asceticism to taking call that can be very rewarding in an odd way. Expelled through the hospital doors in the morning, sleep-deprived, blinking in the bright sunlight, having been in artificial lighting for the last 28 hours, shockingly warm after 28 hours of frigid air-conditioning, you feel reborn into the world. Little pleasures like breezes and being able to eat whenever you feel like it feel poignant.

It's my last call for a month, before I go to the emergency department. I'm a quarter done with calls for the entire year (an advantage of being in genetics) and at the end of the year have nearly five months with no call...I think I might miss it a little.

Three things I've learned today this week
1. Congenital diaphragmatic hernias - are associated with pulmonary hypertension
2. The differential for congenital diaphragmatic hernia is eventration, where the diaphragm is weak, but not truly herniated
3. Hypokalemia can, in and of itself, cause an electrolyte-wasting tubulopathy

Tuesday, July 12, 2011

So one of my patients was just* diagnosed with cancer. The psychiatrist e-mailed me. The psychiatrist, because we'd thought that all of her symptoms were related to her (overwhelming) anxiety and rushed her out of the hospital.

(*N.B. this post was quarantined for several months, in addition to changing of several possible demographic features to ensure that there is no clear connection to any specific patient)

I had inherited the patient from the previous intern when I came on, which is always hard, because you don't really get your own first impression. My attending had felt really strongly about the psychiatric nature of her symptoms and about rushing her out of the hospital. I wasn't sure I agreed, but I didn't have a strong sense of the patient and my attending was very strong willed. On the second to last day of her admission, I talked on the phone with the psychiatrist and she had said to me: "you know, I'm still not convinced that all of her symptoms are psychiatric" and I'd replied "off the record, I'm not sure either."

But to be fair, the next words I'd said were: "but I am convinced that she has nothing physiologic that is rapidly progressive or threatening her well-being or will benefit from an inpatient admission." And that, even with the retrospectoscope, I completely stand behind. I'm not even convinced, even now, knowing that we're discussing a patient with a metastatic malignancy diagnosed one week later, that any of the symptoms for which she was admitted have anything to do with her cancer. (She got diagnosed after presenting with a totally new symptom a week after discharge)

You hear these horror stories of missed cancer diagnoses, by Horrible-Bad-Doctors and think "how could they not have known." And the answer, at least in this case is two-fold
1. Patients with high levels of anxiety and high levels of somatization bombard you with every complaint that they can think of and every possible diagnosis that they read in the internet and it's hard to see the forest for the trees. You think "well, I can't think of a diagnosis that contains all of those symptoms" and "all of the diagnoses that this patient has suggested don't fit" so you dismiss the entire package. And 99% of the time, that's the right response. But even hypochondriacs and patients who somaticize develop true organic illness, buried among the somatic complaints.
2. The goals of a hospital admission from the point of view of being a doctor are different than the goals of a hospital admission from the point of view of being a patient. As a doctor, a patient should be in the hospital only so long as necessary to establish a safe discharge (in which airway, breathing, circulation and hydration/nutrition can be accomplished.) It's my job in the hospital to make sure that the patient doesn't have anything rapidly progressing that would make them unsafe, but not my job to diagnose every symptom. Diagnosis is largely left to the outpatient realm.

It's still scary. I'm glad someone diagnosed it.

Three more things

This afternoon, after call, I went to a lecture by my department chair on the history of inborn errors of metabolism. He focused on how the discoveries leading up to the modern understanding of inherited genetic diseases revolutionized how humanity thinks of itself. Namely, the idea that inherited characteristics and even more specifically, the mind is governed by biochemical principles. It was a really inspirational, fascinating talk. Anyway, posting post-call, so without further ago: here's what I learned today

1. Neonates generally don't benefit from ventilator rates less than 10 (this only kind of counts -- I totally knew this, but didn't make use of my knowledge at 5:30 AM.)
2. People with PKU who are treated early average a normal IQ but often have subtle cognitive differences, especially decreased executive functioning.
3. Glycogen storage disease type I patients cannot ever mobilize glucose in response to glucagon, but type III patients can if they have been fasting for less than 2 hours.

Bonus: Apparently the phrase "Selling coals to Newcastle" is similar to "Preaching to the choir," because Newcastle exports a lot of coal. However, it's historically inaccurate because lots of people have profited by selling coal to Newcastle. Honestly, to me, it sounds like an Iron Dragon reference. (Selling dragons to Nordkassel?)