Sex and Measurement

We know with a good deal of certainty that unprotected sex exposes individuals to potentially life-threatening illness. We also know that all sexual encounters are not the same and, especially since the HIV/AIDS epidemic, researchers have been trying to figure out what sexual behaviors are riskiest and how to use this information towards better micro and macro-focused prevention efforts.

As with all research, a key issue is measurement. Our models to predict individual behavior are usually only as good as our data. As you might imagine, sex can be a personal topic. One may be reluctant to tell a survey interviewer/doctor/friend about their sexual activities, obscuring the whos, hows and whens that are oh-so-important for public health.

Some recent work provides insight into the scale of the measurement problem. A paper by Alexandra Minnis and colleagues compared self-reported sexual activity with biomarkers of exposure (a test based on PSA which can detect exposure to semen in the previous two days) in a sample of Zimbabwean women. The results were sobering: 52% of women who had positive biomarkers said that they engaged in protected sex in the last two days; 23% reported having no sex at all!

In another paper, Brendan Maughan-Brown and I looked at a sample of young adults in Cape Town, South Africa. Our study focused on concurrent sexual partnerships, intuitively defined as the presence of (temporal) overlap between sexual relationships with two distinct partners. There is a hot debate right now on whether such partnerships have been driving the HIV/AIDS epidemic in sub-Saharan Africa. Unfortunately, this debate has been held back by the availability of good data.

Recently, UNAIDS came out with some guidelines on how to standardize and better measure concurrency. We assessed the effectiveness of these guidelines by assessing whether individuals who reported having concurrent relations also reported more than one sexual partner. What we found was surprising: among those who reported only one sexual partner in the last year, nearly 1 out of 6 reported having concurrent sexual relations during this period! We conclude that the UNAIDS methods, which involves asking individuals about each sexual partner they've had and the start and end dates of those partnerships, may actually underestimate the prevalence of concurrency by a significant amount by not fully accounting for all sexual partners.

As both these papers suggest, we have a long way to go before we can credibly claim that we have precise, unbiased estimates of sexual behavior. It would be useful to divert some of time we all spend on linking specific sexual behaviors to health outcomes to figuring out how to get the measurements of those behaviors right in the first place.

A Poignant Opening to the Innings

Today was the second of a 10-day orientation to my internal medicine residency. It's a bit like summer camp right now: the schedule is friendly, the people are even more friendly, and everyone is smiles and giggles. It's been celebratory as well, as if a continuing acknowledgment of our finishing medical school. However, I snapped out of this post-medical school graduation reverie this afternoon when I met one of my future patients.

While I was visiting my to-be clinic site with three to-be colleagues, an African-American gentleman in a baseball cap, who had been watching me while on a tour of the facility, came up to me and plainly stated: "So, you're my doctor." I must have looked at him blankly because he followed it up by saying: "You're the guy with the really long name right? You're my doctor."

I was a bit taken aback, until I realized that this nice gentleman was indeed going to be one of my patients. Every year, my internal medicine program graduates a class of residents. Each resident has a panel of outpatients that they have taken care of over the three years of the program. At the end of residency they turn their panels over to one of the incoming interns. This particular patient is one of the 100 or so I'll be "inheriting" from my senior.

"My doc told me that she's leaving and that you're the new guy," he went onto explain, "So...what is your name?" I started out by saying, "Hey, I'm Atheen" - and then I caught myself. "I'm Doctor Atheendar" I told him, steadying my voice. I gave him a firm handshake, too, instinctively, yet still theatrically moving my left hand over to additionally grasp his right, as if to say "yeah, I'm new - but I got this." Being so unsure about my abilities, knowledge and competence as a physician-in-training, I thought I saw a hint of skepticism in his eyes. But it couldn't have been, because he suddenly smiled broadly and stated proudly, as he looked at the nurse nearby, "HE is my doctor."

And so I am. And so it begins - humbling and inspiring, all at once.

Good Articles on US Health Care

The most recent issue of the Journal of Economic Perspectives contains some excellent articles related to health care reform. The articles cover everything from the effects of medical malpractice reform to the impacts of payment structures to physicians on cost growth. All of the articles are written by top health economists with a great deal of research and policy experience. My two favorite pieces examine the role of administrative costs in explaining cross-country differences in health care expenditures and the future of comparative effectiveness (and cost-effectiveness) research in health care decision making. Definitely check it out!

Poor Economics

I am working through this great book by MIT economists Abhijit Banerjee and Esther Duflo called Poor Economics. This beautifully written tome goes through various problems in economic development and discusses how evidence from the fast growing array of randomized field experiments in development economics can be used towards designing incisive policy interventions. What I love about this book is that it is theoretical and practical all at once. While there is still a healthy debate over the utility of experiments in development economics (see this recent post by Chris Blattman, and this one), what can't be argued is the importance of this methodology as at least a complementary tool in our quest to understand why some places are poor and others are not.

One of my favorite aspects of this new book is the accompanying website (linked above). In addition to access to various tables and datasets for 18 different countries, the website has a link to lectures on Banerjee and Duflo. The lectures on health, in particular, are quite interesting: they cover prevention, deworming, the importance of information, and the role of health in development. Some of these are practical resources that would be highly useful for health care practitioners who are interested in global health.

Lost in the Mail

I just read an interesting paper by Marco Castillo and coauthors on crime in Peru. The study involves a field experiment where the researchers sent out a bunch of envelopes to people involved in the experiment. They signaled the presence of valuable items in the envelopes by making them thicker and/or implying that the letters were sent between relatives (who might be more likely to send valuable things).

This is a clever paper with three really interesting findings:
1) 18% of the envelopes never made it to their destination.
2) Thicker envelopes and those addressed to putative relatives were far less likely to make it.
3) Mail sent to poor neighborhoods did not make it to its destination 18% of the time and mail sent to really rich neighborhoods failed to arrive about 10% of the time. Where most of the mail was lost is in middle income neighborhood. Apparently, this is where the trade-off between the expected value of the envelope contents and the risk of facing retribution due to complaints from influential people is maximized.

Here's the kicker: Peru's mail system is privatized. While privatization is often tossed around as a solution to inefficiencies in developing countries, this paper makes the great point that such changes may have little impact if employees in the system are not held accountable. Ultimately, bad incentives are bad incentives are bad incentives.

Write Our Future...

...is the name of a fantastic NGO that my good friends Brendan and Rebecca Maughan-Brown have started in South Africa (you may recognize Brendan as a frequent co-author of mine in previous posts). The broad goal of WoF is to intervene on disadvantaged children in South Africa to improve health, nutrition and education.

Currently, the Maughan-Browns are working towards providing school-based meals for 100 children for an entire year in the Eastern Cape, where budget issues have led to the cessation of a government-funded program doing the same. It's a great cause, as school meals have been shown to increase attendance and perhaps even test scores, both of which can have important long-run benefits.

I encourage you to donate if you are interested. The Maughan-Browns are smart people looking for evidence-based, high impact interventions. They are running WoF with low overheads, guaranteeing that your money is well spent.

The Internet and Prescription Drug Abuse

Abuse of prescription drugs has grown markedly over the last decade or so. Some have argued that this is due to the growth in online pharmacies, particularly ones that do not require physician visits prior to dispensing medications or, more ominously, ones that do not require any physician approval or prescription or even questionnaires to assess medical histories.

A recent paper by Anupam Jena and Dana Goldman argues that this connection might be quite real. The authors find that a 10% increase in the use of high speed internet - which increases access to online pharmacies - at the state level is associated with a 1% increase in admissions to treatment facilities for prescription drug use. Importantly, this finding is robust to a variety of falsification checks. In particular, the authors show that admissions for abuse of other drugs, such as cocaine and alcohol, whose purchase is unlikely to be linked to access to internet, did not rise with the proliferation of internet during the same time period.

Interesting Global Health Policy Articles

The January 2010 issue of PLoS Medicine contains four interesting articles on the "global health system" The articles define what this system is, discusses the role of nations within this larger system and talks about how to strengthen it's effectiveness. These pieces are written by leaders in the field and provide some concrete discussion on a concept that has gained currency over the last few years, that global health is a policy domain of importance and that nations can be thought interlinked as part of a larger "health ecology" when developing policies to address morbidity and mortality the world over.

For more on global health and global health governance, you may want to check out this interview of one of my thesis committee members, Yale University Professor Jennifer Prah Ruger. Her work (linked here) focuses on this broader global health system, linking insights from ethics, politics, policy and economics to understand how and when investments in international health are and should be made.

Finally, for a topical piece on health care worker shortages worldwide, and the role of the United States in alleviating these, see this great essay by Yale medical student (and my former roommate!) Dayo Fadelu.

Non-Technical Introduction to Causal Inference/Methods

Hi everyone, the blog is back in business.

I recently came across a great working paper seeking to introduce econometric methods geared towards understanding causality to a non-expert audience. I'm particularly excited about this because I think many of these methods could really be useful in medical care/clinical questions where it is either unethical or technically difficult to randomize patients (and yes, there are still plenty of those!). For whatever reason, these methods are, in my estimation, rather underutilized in medicine.

Obviously, while the linked piece is geared towards education policy, the methods can be used in any context. Here is the abstract:

Education policy-makers and practitioners want to know which policies and practices can best achieve their goals. But research that can inform evidence-based policy often requires complex methods to distinguish causation from accidental association. Avoiding econometric jargon and technical detail, this paper explains the main idea and intuition of leading empirical strategies devised to identify causal impacts and illustrates their use with real-world examples. It covers six evaluation methods: controlled experiments, lotteries of oversubscribed programs, instrumental variables, regression discontinuities, differences-in-differences, and panel-data techniques. Illustrating applications include evaluations of early-childhood interventions, voucher lotteries, funding programs for disadvantaged, and compulsory-school and tracking reforms.

Enjoy!

The Long-Arm of Childhood Exposure to War

As if war wasn't destructive enough, a new working paper by Mevlude Akbulut-Yuksel at Dalhousie University finds that childhood exposure to conflict-induced destruction has a wide variety of consequences in adulthood:

During World War II, more than one-half million tons of bombs were dropped in aerial raids on German cities, destroying about one-third of the total housing stock nationwide. This paper provides causal evidence on long-term consequences of large-scale physical destruction on the educational attainment, health status and labor market outcomes of German children. I combine a unique dataset on city-level destruction in Germany caused by Allied Air Forces bombing during WWII with individual survey data from the German Socio-Economic Panel (GSOEP). My identification strategy exploits the plausibly exogenous city-by-cohort variation in the intensity of WWII destruction as a unique quasi-experiment. My findings suggest significant, long-lasting detrimental effects on the human capital formation, health and labor market outcomes of Germans who were at school-age during WWII. First, these children had 0.4 fewer years of schooling on average in adulthood, with those in the most hard-h! it cities completing 1.2 fewer years. Second, these children were about half inches (one centimeter) shorter and had lower self-reported health satisfaction in adulthood. Third, their future labor market earnings decreased by 6% on average due to exposure to wartime physical destruction. These results survive using alternative samples and specifications, including controlling for migration. Moreover, a control experiment using older cohorts who were not school-aged during WWII reveals no significant city-specific cohort trends. An important channel for the effect of destruction on educational attainment appears to be the destruction of schools and the absence of teachers, whereas malnutrition and destruction of health facilities during WWII seem to be important for the estimated impact on health.