Medicine

Canada facts of the day

by on December 26, 2017 at 11:36 am in Data Source, Law, Medicine | Permalink

The estimate comes from Canada’s bureau of statistics, which studied marijuana consumption between 1960 and 2015.

The government has promised to research the drug’s affect on the economy and society as it ramps up its plans to legalise cannabis next summer.

The report also found that use has gone up over the years as it has become more popular with adults.

In the 1960s and 1970s cannabis was primarily consumed by young people, according to Statistics Canada.

But in 2015, only 6% of 15-17 year olds smoked cannabis recreationally, compared to two thirds of adults over 25.

Here is the story, via Mark Thorson.

Uber as an ambulance substitute

by on December 26, 2017 at 2:37 am in Medicine, Travel | Permalink

Using an ambulance to travel to the hospital in an emergency can cost upwards of $1,000 USD. Now research demonstrates that a significant number of people are instead choosing Uber to perform the same service.

The paper – currently being peer reviewed – examines the effect on ambulance usage as Uber was introduced to 766 cities across 43 states. According its findings, even the most conservative estimate shows a seven percent reduction in people traveling via ambulance where the service is available.

Here is the full story, via Jeffrey Deutsch.  File under “Even with surge pricing, bending the cost curve.”

So says Keith A. Meyers, job candidate from University of Arizona.  I found this to be a startling result, taken from his secondary paper:

During the Cold War the United States detonated hundreds of atomic weapons at the Nevada Test Site. Many of these nuclear tests were conducted above ground and released tremendous amounts of radioactive pollution into the environment. This paper combines a novel dataset measuring annual county level fallout patterns for the continental U.S. with vital statistics records. I find that fallout from nuclear testing led to persistent and substantial increases in overall mortality for large portions of the country. The cumulative number of excess deaths attributable to these tests is comparable to the bombings of Hiroshima and Nagasaki.

Basically he combines mortality estimates with measures of Iodine-131 concentrations in locally produced milk, “to provide a more precise estimate of human exposure to fallout than previous studies.” The most significant effects are in the Great Plains and Central Northwest of America, and “Back-of-the-envelope estimates suggest that fallout from nuclear testing contributed between 340,000 to 460,000 excess deaths from 1951 to 1973.”

His primary job market paper is on damage to agriculture from nuclear testing.

Here is the abstract to The Geography of Poverty and Nutrition: Food Deserts and Food Choices Across the United States (free version) by Allcott, Diamond, and Dubé:

We study the causes of “nutritional inequality”: why the wealthy tend to eat more healthfully than the poor in the U.S. Using two event study designs exploiting entry of new supermarkets and households’ moves to healthier neighborhoods, we reject that neighborhood environments have economically meaningful effects on healthy eating. Using a structural demand model, we find that exposing low-income households to the same food availability and prices experienced by high-income households would reduce nutritional inequality by only 9%, while the remaining 91% is driven by differences in demand. In turn, these income-related demand differences are partially explained by education, nutrition knowledge, and regional preferences. These findings contrast with discussions of nutritional inequality that emphasize supply-side issues such as food deserts.

This is a good paper with a credible research design and impressive data from some 35,000 supermarkets covering 40% of the United States. Moreover, because of the widespread attention given to “food deserts” this paper probably had to be written. But color me un-surprised. The results are obvious.

Indeed, I feel that in recent years I am reading a lot of papers that aim massive firepower on weak hypotheses. As an explanation for obesity and poor eating habits, the idea of “food deserts” was absurd. The reasons are manifold. Even in food deserts it’s actually not that difficult to get healthy food and, contrary to popular belief, healthy food is not especially expensive. Try an Asian supermarket for plenty of cheap produce. Indeed, in any part of the United States you can find plenty of poor-people eating healthy foods and plenty of rich people eating unhealthy foods.

The food deserts idea was especially implausible for America because Americans spend less of their income on food consumed at home (6%) than any other nation. The Dutch, for example, spend (12%) of their income on food, the Italians and Japanese (14%), the Vietnamese (35%). There is plenty of room in the American food budget for healthy eating. Finally, Allcott, Diamond, and Dubé show that relative to unhealthy food, healthy food is actually a bit cheaper in low-income areas.

More importantly, just open your eyes. Walk into a fast food joint in a food desert and ask yourself, do the customers really want brussel sprouts but are reluctantly settling for Chips Ahoy? The idea is ridiculous and not a bit insulting in denying agency to the people who live in low-income areas. If what people living in food deserts wanted was brussel sprouts, they would get them.

The Whole Foods class think their kale and kombucha are so obviously superior to what the poor eat that the only possible explanation for poor eating is that poor people are denied choice. Yet put an inexpensive but colorful produce stand next to a McDonald’s and you can be sure that the customers will differ by class. Why the poor choose to eat differently than the rich is an interesting and important question but one more amenable to answers focusing on culture, education and history than price and income. The idea applies widely.

Understanding the purpose of sex is a fundamental unresolved problem in evolutionary biology. The difficulty is not that there are too few theories of sex, the difficulty is that there are too many and none stand out. To distinguish between theories, we ask: Why are there no triparental species with offspring composed of the genetic material of three individuals? A successful theory should confer an advantage to biparental sex over asexual reproduction without conferring an even greater advantage to triparental sex. Of two leading theories (red queen and mutational), we show that only one is successful in this sense.

That is a new Economic Journal paper by Motty PerryPhilip J. Reny, and Arthur J. Robson.  Of course the core question is a classic example of thinking at the margin.  The core conclusion is that mutations continue to rise with the number of sex-participating partners, but in simple Red Queen models the limiting features of the genotypes is the same whether there are two, three, or more partners.  The argument on pp.2739-2741 is not readily blog-summarizable, and I do not grasp it fully, but at the moment I have the following intuition.  If a parasite attack comes, the species needs only move away from the targeted genome to continue reproducing, due to some all-or-nothing assumptions about the nature of the attack.  This differs from the mutational game, where there is always some marginal (expected value) gain from moving yet further away from the initial nature of the species.  Playing a game against an identified opponent brings a better-specified and more stable and less varying response strategy than playing a game against an as-yet-unidentified opponent.  That isn’t how the authors put things, but…

Since we don’t observe much three-party reproduction (hardly any in fact), that suggests the Red Queen model is more likely to apply.

For the pointer I thank TEKL.

Are there genetic vulnerabilities for depression across cultures?

Genetic vulnerability differs substantially from country to country. East Asian contexts, for example, show a high prevalence of genes associated with depression. Yet, despite these vulnerabilities, they develop fewer cases of the disorder. One hypothesis is that genetic vulnerabilities have co-evolved with culture, creating extra protective factors (in this case, extra interdependence). However, when these people leave their cultural contexts, they have a higher risk of developing depression.

That is an interview with Yulia Chentsova-Dutton, associate professor of psychology at Georgetown, and a researcher in this area.  You can imagine further applications of this mechanism.  The interview has other interesting points, for instance:

What is the role of emotion regulation?

Emotion regulation is increasingly becoming understood as a core factor in all affective disorders. In western societies, we don’t see enough adaptive strategies like reappraisal: learning to tell yourself a different story that would eventually lead to different emotions. There is also not enough social regulation of emotion, which occurs by sharing our emotions with others. Research shows that cultures can facilitate functional regulation strategies. For example, Igor Grossmann’s work shows that Russians make rumination (generally considered a dysfunctional strategy) more functional by encouraging people to ruminate about the self from another person’s perspective, making rumination almost reappraisal-like in its quality.

Do read the whole thing.

NZ Ministry of Health: People who donate a kidney or part of their liver can now do so knowing they can be fully compensated for lost earnings as a result of their donation surgery.

The Ministry of Health will be implementing compensation for live organ donors from 5 December. People who donate a live organ will be fully recompensed for lost earnings for up to 12 weeks while they recover. This will be paid weekly following the donation surgery. In the past donors received some assistance in the form of a benefit for this.

Former GMU student, Eric Crampton, now Senior Fellow at University of Canterbury had a role in the design.

Hat tip: Frank McCormick.

That is by by Caitlin Knowles Myers, and the full title is “The Power of Abortion Policy: Reexamining the Effects of Young Women’s Access to Reproductive Control.”  It is published in the most recent JPE, here is the abstract:

I provide new evidence on the relative “powers” of contraception and abortion policy in effecting the dramatic social transformations of the 1960s and 1970s. Trends in sexual behavior suggest that young women’s increased access to the birth control pill fueled the sexual revolution, but neither these trends nor difference-in-difference estimates support the view that this also led to substantial changes in family formation. Rather, the estimates robustly suggest that it was liberalized access to abortion that allowed large numbers of women to delay marriage and motherhood.

In other words, the pill was less influential than you might think.  And from the paper proper:

…policy environments in which abortion has legal and readily accessible by young women are estimated to have caused a 34 percent reduction in first births, a 19 percent reduction in first marriages, and a 63 percent reduction in “shotgun marriages” prior to age 19.

And:

Between the 1950 and 1955 birth cohorts, the fraction of women having sex prior to age 18 increased from 34 to 47 percent.

And:

…cohorts that experienced the most rapid changes in sexual behavior exhibited little change in fertility.

And:

Lahey (2014)…finds that the introduction of abortion restrictions in the nineteenth century increased birthrates by 4-12 percent…

I thought this was one of the most interesting papers I have read all year.  Here is an earlier, ungated copy.

The Good Wife

by on November 30, 2017 at 11:22 am in History, Medicine | Permalink

Steffanie Strathdee, [is] the associate dean of global health science at the University of California, San Diego. In 2016, she helped revive her husband from a coma with a combination of phage therapy and antibiotics after he’d come back from Egypt with an untreatable bacterial infection, and she’s since become a kind of phage activist, helping others, like the Smiths, coordinate their own phage hunts.

That’s just a sidenote in an article on phages, viruses that kill bacteria. Seems like there’s a movie there.

Phages were long used in the Soviet Union to treat bacterial infections but are only now being studied in the West as bacteria evolve resistance to antibiotics.

Addendum: Dallas Weaver makes excellent points in the comments.

The North Korean defector

by on November 28, 2017 at 3:04 pm in Current Affairs, Medicine | Permalink

Lee said he had never seen such an extreme case of parasitic infection. The soldier had worms not seen in South Korea since the 1970s, but they appeared to be somewhat common north of the border. In a 2014 study, South Korean doctors sampled 17 females who escaped North Korea and found that seven of them were infected with parasitic worms, according to the BBC. They also had higher rates of diseases such as hepatitis B and tuberculosis.

What was just as curious were the raw corn kernels found in Oh’s [the defector’s] stomach, which shocked many South Koreas. North Korean soldiers typically have a higher ranking on the food-rationing list, so it was alarming that the soldier had been eating uncooked corn.

Some reports claim that North Korean soldiers have been ordered to steal corn from farmers to fend off hunger.

Here is further information.

Recent research shows increasing inequality in mortality among middle-aged and older adults. But this is only part of the story. Inequality in mortality among young people has fallen dramatically in the United States converging to almost Canadian rates. Increases in public health insurance for U.S. children, beginning in the late 1980s, are likely to have contributed.

Here is the full article, by Janet M. Currie, via the excellent Kevin Lewis.

The life expectancy gap at age 40 between high income and low income individuals is substantial. I explore how medical expenditures and unhealthy behaviors account for the life expectancy gap. The data reveals the following. First, low income individuals tend to spend more on healthcare than high income individuals at all ages. Moreover, health disparities by income is salient due to differences in unhealthy behaviors such as heavy smoking. To answer how much dierences in access to medical services and unhealthy behaviors can explain in light of these stylized facts, I construct a life cycle model. The distinctive features of the model are that it flexibly incorporates unobserved, potentially correlated initial human and health capital stocks and embed unhealthy behaviors. Furthermore, the model includes two health systems: private health insurance and Medicare. The main findings are i) differences in access to medical care driven by income inequality potentially accounts for 12.5% of the life expectancy gap, ii) health insurance increases longevity for low income individuals, but modestly, iii) the health condition when young shapes the trend in average medical expenditures by income groups and iv) the impact of differences in unhealthy behaviors is predominant in understanding the life expectancy gap.

That is from Tomoaki Kotera, a job candidate from the University of Wisconsin, here is the paper itself.

In 2013, the Post-Polio Health International (PPHI) organizations estimated that there were six to eight iron lung users in the United States. Now, PPHI executive director Brian Tiburzi says he doesn’t know anyone alive still using the negative-pressure ventilators. This fall, I met three polio survivors who depend on iron lungs. They are among the last few, possibly the last three.”

…In the 1940s and 1950s, hospitals across the country were filled with rows of iron lungs that kept victims alive. Lillard recalls being in rooms packed with metal tubes—especially when there were storms and all the men, women, adults, and children would be moved to the same room so nurses could manually operate the iron lungs if the power went out. “The period of time that it took the nurse to get out of the chair, it seemed like forever because you weren’t breathing,” Lillard said. “You just laid there and you could feel your heart beating and it was just terrifying. The only noise that you can make when you can’t breathe is clicking your tongue. And that whole dark room just sounded like a big room full of chickens just cluck-cluck-clucking. All the nurses were saying, ‘Just a second, you’ll be breathing in just a second.’”

…Mia Farrow only had to spend eight months in an iron lung when she was nine, before going on to become a famous actress and polio advocate.

Here is the full story, via the excellent Samir Varma.

Once a drug has been approved for some use it may be legally prescribed for any use. New uses for old drugs are discovered quite often so off-label uses can be very different from FDA approved uses. Mitomycin, for example, was approved to treat stomach and pancreatic cancer but is used off-label in laser-eye surgery. Drugs prescribed off-label have not been through FDA-approved efficacy trials for the off-label use. In Assessing the FDA via the Anomaly of Off-Label Drug Prescribing I pointed out that off-label prescribing, therefore, gives us a window onto a world with much less FDA regulation.

Since off-label prescribing is common and in rapidly progressing areas of medicine often the gold-standard, I argued that the behavior of physicians validated off-label prescribing and demonstrated that physicians were willing and able to draw upon non-FDA sources of information to make rational prescribing decisions. Dan Klein and I also showed that physicians are supportive of off-label prescribing saying, for example, that it would be “crazy” to require FDA approval for off-label uses.

The support of physicians for off-label prescribing is telling but not dispositive. Perhaps physicians make hubristic mistakes in prescribing off-label. A new paper by Ladanie et al. (including John Ioannidis) provides important information. The authors search the literature for all the RCTs when an off-label drug was pitted against an on-label drug. They conclude:

Our meta-epidemiological analysis of 25 different treatment indications for off-label drug use
provides no empirical evidence supporting any assumption of generally inferior treatment
effects associated with off-label use. On the contrary, the summary effect estimates across all
indications would even be compatible with more favorable effects, on average, of the off-label
treatment. However, the heterogeneity is substantial and the on-label comparators are not
necessarily the best approved treatment option in all 25 topics. While some off-label
treatments are clearly better, others are clearly not.

The finding is especially impressive because although off-label treatments are sometimes the gold standard they are also often used when standard treatments have failed. Thus, in an RCT, off-label treatments could be worse on average and yet still provide a very useful weapon in the medical armory.

One might argue that if off-label treatments are as good as FDA-approved treatments then the FDA should have higher standards. FDA required clinical trials, however, already cost hundreds of millions of dollars and years of effort, creating drug lag and drug loss. Rather than condemning the FDA, what these results indicate is that the medical system–physicians, hospitals, insurers, scientists–does a good job at evaluating new uses for old drugs. As Dan Klein and I noted in our precis on off-label prescribing:

The off-label experience testifies to the fact that much knowledge
about efficacy and safety is produced outside the FDA regulatory
apparatus. The Pharmacopoeia’s recognition of off-label
indications years ahead of the FDA demonstrates that physicians
and scientists have certified thousands of drug indications quite
independently of the FDA, even when those indications are not
very closely related to the original indications. In addition to the
Pharmacopoeia, there are several other forms of professional certification,
including the American Hospital Formulary Service Drug
Information, HMO formularies, and a wide
array of specialist professional periodicals
and information services. NIH studies,
clinical results and determinations
from other countries, and other professional,
science-based judgments are
examples of nongovernmental, non-mandatory
certification.

Hat tip: Michelle Dawson.

There is a new NBER working paper on these topics, by Anna Chorniy, Janet Currie, and Lyudmyla Sonchak, here is the abstract:

In the U.S., nearly 11% of school-age children have been diagnosed with ADHD, and approximately 10% of children suffer from asthma. In the last decade, the number of children diagnosed with these conditions has inexplicably been on the rise. This paper proposes a novel explanation of this trend. First, the increase is concentrated in the Medicaid caseload nationwide. Second, nearly 80% of states transitioned their Medicaid programs from fee-for-service (FFS) reimbursement to managed care (MMC) by 2016. Using Medicaid claims from South Carolina, we show that this change contributed to the increase in asthma and ADHD caseloads. Empirically, we rely on exogenous variation in MMC enrollment due a change in the “default” Medicaid plan from FFS or MMC, and an increase in the availability of MMC. We find that the transition from FFS to MMC explains most of the rise in the number of Medicaid children being treated for ADHD and asthma. These results can be explained by the incentives created by the risk adjustment and quality control systems in MMC.

The economics of medical diagnoses remain a drastically understudied area.