Interesting take on evidence-based policy

The anti-alcohol folks are pushing for stronger and mandatory warnings on drinks about the dangers of alcohol consumption during pregnancy. 

This bit was particularly interesting:

RESISTANCE FROM INDUSTRY TO BE EXPECTED 

Baddock argues attempts by the alcohol industry to promote measures to reduce FASD have been ineffective and rather seek to debate the evidence.

The NZMA submission urges decision-makers to be aware of, and pre-empt, industry counter-arguments to public health measures such as mandatory labelling.

Baddock says a standard alcohol industry tactic has been to cite lack of evidence as a reason not to do something, which has been used by others such as the tobacco industry to "thwart and delay" public health measures like plain packaging.

"It's not just alcohol. I think any industry tends to be resistant to anything mandatory that might affect their sales."

However, she is hopeful the alcohol industry will "come on board" with mandatory pregnancy warnings. 

"I would love to see the alcohol industry put up their hand and say FASD is a real problem and we need to be helping reduce the harms done [by alcohol]." 

Traditionally, the status quo has some weight. Those proposing changes to the status quo have to provide some evidence that the change will be beneficial - that the gains will exceed the costs. In areas where evidence on gains and harms is hard to come by, we can look to international evidence - or run trials.

It is a bit odd to pre-emptively say (my paraphrase): "Hey, we don't have any evidence that our policy proposal will do any good. We ran some focus groups suggesting that people don't pay much notice to current labels, but we have no particularly good reason to expect that mandatory labeling will change real-world behaviour in the cohort we should be worried about. But anybody pointing out the absence of evidence - we're going to pre-emptively say that they're industry shills."

Another fun bit - the anti-alcohol people worry that messages like 'it's safest not to drink while pregnant' might strengthen beliefs that light drinking in pregnancy is harmless.

Here's Emily Oster on that. She included a nice section on alcohol in her review of all of the evidence on the dos and don'ts during pregnancy.

There exists no large (or even small) randomized trial about drinking during pregnancy; such a thing is never likely to exist. This is not unique to drinking, of course – there are no large randomized trials of Tylenol usage in pregnancy, either, just a lot of large observational studies. And some women will read the existing evidence and still choose to abstain. But there is a growing body of data suggesting that, if women choose to have a glass of wine, there is no evidence they are harming their baby.

Telling women that an occasional glass of wine is more harmful to their baby than heroin or cocaine is misleading and may also be potentially dangerous. It surely would not be supported by the vast majority of the medical establishment. Focusing on punishing and shaming women who choose to have an occasional glass of wine during their pregnancy also takes away important focus from helping women who are struggling with truly problematic drinking and the social problems that often come with it. 

So they're worried that people might draw the correct conclusion from the labeling - that heavy drinking during pregnancy is a very very bad idea, but a glass of wine every other day is going to be fine.

Again - the anti-alcohol people will not be happy until they have incrementally gotten us to alcohol plain packaging. It's salami-slice tactics, exactly the same as used in the push against tobacco,  incrementally piling on restrictions until the only thing allowed on the packaging is warning labels and small-print indication of the manufacturer.

Expecting Better

My review of Emily Oster's excellent Expecting Better appeared in this weekend's Christchurch Press; it's copied below. I've added in a few relevant links.

I had a lot of questions for our midwife when we expected our first a few years ago. Questions like, "Which shared-care obstetrician has the best delivery outcomes adjusting for the risk of the patient base?" My wife later warned me that our excellent midwife seemed to think me some kind of pod-person for asking questions about the evidentiary base around the standard pregnancy recommendations. Had we then had a copy of Professor Emily Oster's new book, "Expecting Better", I wouldn't have needed to torture her. I should send her a copy now. And if you're expecting, or thinking about getting pregnant, you should pick up a copy too.

Emily Oster is a University of Chicago economist. When she and her husband, economist Jessie Shapiro, decided to start a family, she started into the data. The pregnancy books and doctors provide a lot of recommendations. Some of these benefit the foetus at next to no cost to the mother. Others provide only a small benefit to the foetus while imposing some cost on the mothers. And, sadly, some impose reasonable cost on the mother while doing nothing to help.

Oster provides us the story of her pregnancy, in an accessible and conversational style, while walking us through the research she conducted along the way. While trying to conceive, she worked out the conception probabilities at each date of the cycle. She also found that while obesity makes it harder to conceive, merely being overweight isn't much different from being normal weight. When the pregnancy test came back positive, she wanted to know, and quickly, whether she could stick with her standard caffeine addiction. She charted the probability of miscarriage at every week of pregnancy. All the “no, you can't eat that” rules? She shows us which of them make sense. Later in the book, she walks through the difficult cost-benefit analysis around amniocentesis - the exact same calculation we ran ourselves.

So what's an economist doing writing a book on pregnancy? Economists are good at framing tradeoffs between risks and benefits to help others decide what's right for them. Further, economists' statistical toolkits are built for solving the kinds of statistical inference problems that plague the population health literature. If a study finds mothers who drink more coffee during pregnancy have worse outcomes, is it because of the coffee, or is it because more nauseous women both have better outcomes and find coffee unappealing? Economists' training helps us sort out which studies have done a reasonable job and which ones really haven't. Oster concludes that a couple cups of coffee a day are just fine.

If costs to the mother never mattered, and if statistical inference were easy, then life would be simpler. But in most cases, we need to weigh how much real risk is imposed by, say, smoking a cigarette during pregnancy, and then decide whether the benefit to the mother could outweigh the cost to the foetus. Smoking during pregnancy is very risky and even light smoking is associated with worse outcomes, so the calculus for most mothers on that one should be easy. But what about drinking? Oster's review of the literature here coincided perfectly with what I found when I looked at the same studies: light drinking during pregnancy, on the order of a small glass of wine every other night or so, does absolutely no harm to the foetus. Heavy drinking is very very bad indeed. But the bulk of the well-designed studies show no risk, and in some cases some benefits, from light drinking. If a small glass of wine with dinner helps you relax and you've been abstaining because you're scared that one glass will do harm, you're making pregnancy less pleasant than it could be and achieving little for it.

Oster concluded, as I did, that most recommendations in this area seem motivated by the fear of encouraging binge and heavy drinkers to continue such very harmful practices during pregnancy. But is it really ethical to lie to pregnant women because we're scared they can't handle the truth?

Similarly, and at least in North America and the UK, there's no good reason to avoid sushi during pregnancy as the dangerous forms of salmonella there are very rare. Were we ever to contemplate a third child, I'd be investigating whether those strains are at all common around New Zealand. On the other side, gardening is riskier than I had expected because of toxiplasmosis gondi.

I worry that the standard full set of dos and don'ts make pregnancy sufficiently costly and nerve-wracking that some families are smaller than they otherwise would be. A lot of current recommendations seem to be public rituals designed to allow the mother to display how much she cares about the infant, and for others to display similar amounts of care for the infant by tut-tutting the mother-to-be. This does harm. We make pregnancy a worse experience, and too-often needlessly so, for the mothers who care and worry most about following all the rules. I worry further that by promoting rules that most people know make little sense, we encourage some mothers to discount even the rules that make a lot of sense. Oster provides a sound assessment of the actual risks to help families make their own decisions about the path through pregnancy that is right for them.

Related posts:

• Naming names
• Transfusions and operating room ethics
• Otago bioethics: Downs edition

Kid Sanity

Bryan Caplan tells us that because the return to parental input is low, we can all ease up on the parental production function. Parents agonise about whether they're doing enough; the ones who do so-agonise are usually doing far too much on any rational cost-benefit calculation. Conclusion? Spread the same amount of total effort over more kids. The reduction in average child quality really won't be that big and you'll be a lot happier in your old age.

But Bryan errs a bit. He neglects that we also could be putting too much effort into antenatal care. Sure sure, there's a big left tail that are screwing up horribly on that front. But that tail isn't reading economics blogs or parenting books written by economists. Instead, the folks who do read econ blogs are busily beating themselves up for having a bit of soft cheese or sneaking a sip of wine during pregnancy. If we are erring in making pregnancy far more costly for our wives than it really needs to be, then we're really screwing up: no matter how convinced we are about Bryan's arguments, if pregnancy is really unpleasant, that up-front cost can kill our future potential unrealised children.*

Emily Oster's forthcoming book then will be a beautiful complement to Bryan's work. Amazon should sell them as a bundle. Doctors, midwives, and right-thinking-tut-tutting-jerks give us all kinds of advice about what good people do. A lot of those really just seemed to be nonsense.

Take alcohol. When we were expecting, none of the advice on alcohol seemed to make sense. Sure, getting drunk seemed a really bad idea. But the dose always makes the poison. So I went and checked the literature and concluded that light drinking during pregnancy was effectively harmless. So Susan had the occasional glass of wine; we were also big fans of Harrington's SobeRing Thought - the low alcohol beer that local brewer Harrington's made for the Lord of the Rings.** And I blogged a bit on how the risks of alcohol during pregnancy seem overstated: if anything, public health folks' warnings that there's no safe level of drinking seem a noble lie intended to dissuade those pregnant women who'd otherwise drink a bottle of scotch in an evening.

If you can't have a glass of wine with dinner every other night during pregnancy, then pregnancy is less fun than it otherwise would be. And so the kind of people who listen to this kind of advice are having too few kids.

Oster seems to have been as annoyed as we were. But she's done something far more constructive about it - she's compiled the evidence for those of us who care about evidence. From the Amazon blurb:

When Oster was expecting her first child, she felt powerless to make the right decisions for her pregnancy. How doctors think and what patients need are two very different things. So Oster drew on her own experience and went in search of the real facts about pregnancy using an economist’s tools. Economics is not just a study of finance. It’s the science of determining value and making informed decisions. To make a good decision, you need to understand the information available to you and to know what it means to you as an individual.

Take alcohol. We all know that Americans are cautious about drinking during pregnancy. Official recommendations call for abstinence. But Oster argues that the medical research doesn’t support this; the vast majority of studies show no impact from an occasional drink. The few studies that do condemn light drinking are deeply flawed, including one in which the light drinkers were also heavy cocaine users.

Expecting Better overturns standard recommendations for alcohol, caffeine, sushi, bed rest, and induction while putting in context the blanket guidelines for fetal testing, weight gain, risks of pregnancy over the age of thirty-five, and nausea, among others.

The tut-tutters are doing real harm here. Lower decile groups hear the "drink nothing" warnings, dismiss them entirely as nonsense, and go on to drink way too much while pregnant, doing real harm. High decile groups hear the "drink nothing" warnings and, adding that to all the other advice they're given about all the other costly-and-useless rituals they must follow during pregnancy, rationally decide to have fewer kids. This is a bad equilibrium. Shame that Oster's book won't be out for another year - the current equilibrium is costly, and the faster we can start fixing it, the better.

* As clarification: there's some optimal number of kids that each couple will decide to have. If the actual cost of having one more kid is lower than the cost parents think they have to face, or the cost they mistakenly decide to impose upon themselves, then optimal family size is a bit larger than the deciding-couple thinks. The deadweight costs of kids who optimally would be born from the parents' perspective but aren't born because of parental cost misperceptions is the problem - I don't think I'm pushing into Parfit territory here. But the problem is my wording, now clarified. Thanks

** Yeastie Boys and Kelly Ryan brewed the beers in this year's Hobbit film.