screening tests and invasive medical procedures

I recently read an article on Forbes about a forthcoming JAMA article about screening test uncertainty and invasive medical procedures [Link]. In the study [Study Link], the researchers gave 727 men hypothetical PSA scores for screening for prostate cancer. The control group was not given a PSA result. Those who not in the control group were given one of three outcomes, leading to four groups.

1. Normal PSA test
2. No PSA test (control group) – no uncertainty
3. Inconclusive PSA test – high uncertainty
4. Elevated PSA test

Men in each group were asked if they would pursue a biopsy, an invasive and expensive medical procedure compared to the PSA test. Groups 2 and 3 are similar in that they don’t have conclusive of cancer. However, group 3 has more uncertainty.

Probability of patients who opted for a biopsy:

1. Normal PSA test – 13%
2. No PSA test (control group) – 25%
3. Inconclusive PSA test – 40%
4. Elevated PSA test – 62%

The issue here is that an inconclusive test gives the same information as doing no test at all, yet those with an inconclusive test want to get a biopsy at a higher rate. In the study, the biopsies are requested by the patients, but in real life, doctors often turn inconclusive tests into expensive and invasive medical procedures.

I had a few other reactions to the issues associated with screening for disease.

With limited resources, inexpensive screening in theory helps to keep health care costs down. A cheap test is supposed to be used to weed out some of the population that does not need more invasive screening test. If disease cannot be ruled out, it may make some sense to retest. Of course, the issue here is that biopsies are chosen at different rates for different inconclusive patients. The results of this study suggests that screening for disease starts a process that is hard to turn off – screening could result in more men being biopsied instead of fewer. This isn’t just an issue with PSA tests.

I also found it interesting that 13% of the population apparently refused to be weeded out.

Humans do not do a good job of figuring out how to effectively use resources to screen for and manage disease. And as we see in this study, humans do not always make better decisions with better information. This is why we need good models of disease and its treatment. With those models in place, we can explore how to effectively target limited healthcare resources at the patients who most need them.

This is a growing area for operations research – identifying how to make good decisions at the patient level for understanding when to do more testing and when to take a wait-and-see approach. For slow-growing cancers such as prostate cancer, a wait-and-see approach may be a good one most of the time (disclaimer: for what it’s worth, I’m not a medical doctor). Waiting and retesting was not an option considered in the study, and maybe the results would be different. A wait-and-see approach is often used for other types of cancers, such as for pre-cancerous legions that could lead to cervical cancer.

For more reading about screening policies, inaccurate screening tests, and unnecessary treatment, read this NY Times article about breast cancer: [Link] Breast cancer can be quite aggressive, especially when it affects younger people, and it is common. I’ll admit that delaying or avoiding mammography is hard to fathom. The article highlights how aggressive mammography policies have led to the discovery of more cancerous and pre-cancerous legions (and thus cancer survivors) but it has not led to higher cancer survival rates. Other issues such as self-exams are also discussed.

I’m looking forward to learning about the latest research in this area at the INFORMS Healthcare Conference in Chicago this summer [Link]. I hope to see many of you there.

 

The numbers behind health care – for a lay audience

In October, This American Life produced two interesting episodes about health interventions and evidence-based medicine that I am just listening to now. These This American Life shows seem fresh and interesting, largely because they try to discuss health insurance/care issues from a quantitative, evidence-based perspective, even though cite few numbers in the episodes.  To illustrate this point, part of the first episode is even titled “Every CAT scan has nine lives,” referring to the side effects of over-using advanced medical techniques such as CAT scans.

The More is Less episode is particularly interesting for OR folks.  It starts with a twenty-minute discussion of some of the cost and effectiveness problems with health care.  The episode steps through one of the problems that grappled the medical community from the 1970s: geographic disparities in hysterectomies and other medical procedures in Maine and Vermont.  This baffled the doctors, since the disparities in hysterectomies across the state could not be explained by demographics, age, religion, or other factors, as was initially suspected.  One of the doctors who performed some of the analysis (Wennberg) concluded that 70% of women would receive hysterectomies in some communities. Maine doctors concluded that disparities were in part based on the doctors choosing to over-perform certain surgeries rather than the patients asking for procedures.

The episode continues to discuss why performing more medical procedures leads to more side effects and potential destruction in some cases, including the PSA tests for prostate cancer, thus exploring the tradeoff between cost and effectiveness.  These issues have been in the news quite a bit lately, particularly with the chance in mammogram screening recommendations.  These discussions in the news have included too much pandering and too little math and analysis, for the most part.   I’ve struggled to find good resources for a lay audience that address the numbers, so this episode was much appreciated.  I’ll leave the rest of the episode a mystery, so you can listen to it yourself.  The second episode (Someone Else’s Money) is not nearly as good, but examines health insurance in more detail.

Podcast Links:  More is Less and Someone Else’s Money.

Link: The Numbers Guy (WSJ) on Mammogram Math is also an interesting read.

Have you found any good references on lay explanations of the numbers behind health care and health insurance?

one more link

Yesterday, I posted a list of links that I shared with my class this semester.  I left one off.  I have quite a few pre-med students, so I like to talk about medical applications when necessary.  I shared a brief history of evidence-based medicine with my students, as conveniently summarized in a Business Week article.  The article is about David Eddy, the medical doctor turned operations researcher who transformed how medicine is practiced by using more math.  The article begs for more OR to be applied to health care applications:

The human brain, Eddy explains, needs help to make sense of patients who have combinations of diseases, and of the complex probabilities involved in each.

The article describes many of the challenges in the medical domain as well as some of the benefits of using advanced analytical methods for approaching medicine.

[Eddy's] PhD thesis made front-page news in 1980 by overturning the guidelines of the time. It showed that annual chest X-rays and yearly Pap smears for women at low risk of cervical cancer were a waste of resources, and it won the most prestigious award in the field of operations research, the Frederick W. Lanchester prize. Based on his results, the American Cancer Society changed its guidelines.

The recent changes in how we screen for prostate cancer and breast cancer are part of Eddy’s legacy.  They are controversial, but few medical treatments have been proven in clinical trials (the article estimates this could be as low as 20%).

[Link]

OR and H1N1

This is the second of three posts about the INFORMS Annual Meeting.

I enjoyed a talk by Dr. Richard Larson of MIT about the timely topic of H1N1 and operations research.  I tuned out much of the alarmist news prior to the conference (to keep my sanity) and instead adopted a rigorous handwashing regimen.  Larson’s talk highlighted the many opportunities for addressing H1N1 issues using operations research, including:

• Queuing for vaccinations.
• Reneging on vaccinations (some health care workers are refusing required vaccinations).
• Timing the vaccinations (before the prevalence peaks) is important for reducing risks, since youths are particularly susceptible to dying from H1N1..
• Locating facilities to manage surge capacity when the epidemic hits.
• Correctly diagnosing and isolating cases of H1N1.
• Supply chains for vaccinations.

Larson and his collaborator Dr. Stan Finkelstein takes a different kind of focus, looking at personal choices, such as hand washing, coughing into sleeves, avoiding handshakes, and avoiding crowds.  They examine this issue through non-pharmaceutical interventions.  Someone infected with H1N1 infects about 1.5 people in the next 24 hours (on average).  This value is the mean of a random variable, which depends on personal choices (like handwashing).  He examines the conditions under which the average number of infections decreases below 1.0, when the virus essentially dies out (Similar to my reasoning on vampire populations).

Finkelstein, a medical doctor, discussed some of the policy results.  Initial reports suggested that H1N1 has a fatality rate of about 50% (Spanish flu has a FR of 3%).  After an initial panic, flu fatigue set in.  And the first wave of H1N1 resemble seasonal rather than pandemic flu.  But after the recent panicking, many of us simply have not been motivated to improve our personal choices to reduce H1N1 transmission.  Case in point, elbow bumping pictured below (instead of hand shaking) did not catch on at the conference as I had hoped. And the anti-bacterial hand gel was not located in useful places at the conference, so I used my own personal stash of anti-bacterial lotion after shaking hands.

I hope some of this research is used to lessen the impact of H1N1 this year before I am transformed into a germ-a-phobe.

Link:  Flu101@MIT

Karima Nigmatulina, after successfully defending the first PhD thesis on our flu research project, bumps congratulatory elbows with advisor Richard Larson.

OR *can* reduce health disparities

After attending the second day of the Virginia Health Equity Conference, I have been convinced that public health is a function of much, much more than just medical treatment.  Paula Braveman provided some figures in her keynote that indicate that the mortality and incidence rates of many infectious diseases drastically reduced before effective medical interventions were introduced.  I had heard this before, but a picture is worth a 1000 words.  I tracked down a few of the images online (see below).   Public health initiatives such as housing, ventilation, improved sewage systems, and education improved health outcomes much more than medical interventions that were later introduced.  This reflects the fact that there are many good proxies for public health that reflect infrastructure, networks, and transportation, all of which are things that we like to evaluate in operations research models.

It strikes me that any operations research models that reflect public health would fit in well with community-based OR initiative.  Those who do research in this area might be interested in a new Springer volume.  The call for papers is pasted below (I could not find a link).  Note that I am not affiliated with this effort.

Proposals for manuscripts on the topic of Community-Based Operations Research are being solicited for an edited volume to be published in the Springer International Series in Operations Research and Management Science, as part of the Advancing the State-of-the-Art handbook series.

“Community-based operations research” (CBOR) is defined as the collection of analytical methods applied to problem domains in which interests of underrepresented, underserved, or vulnerable populations in localized jurisdictions, formal or informal, receive special emphasis, and for which solutions to problems of core concern for daily living must be identified and implemented so as to jointly optimize economic efficiency, social equity, and administrative burdens. This domain was first discussed in a chapter in Tutorials in Operations Research 2007 – OR Tools and Applications: Glimpses of Future Technologies (INFORMS 2007) by Johnson and Smilowitz and subsequently in an article that appeared in the February 2008 issue of OR/MS Today.

As community-oriented operations research, as defined here, is central to the mission of the Section on OR/MS Applied to Public Programs, Service and Needs, submissions from SPPSN members will be especially welcome.

Chapters in this volume can describe current results for a specific research problem, a literature review, or a discussion of the nature of CBOR within the operations research/management science discipline.

Proposals for submissions to this volume should be not more than one page in length, describe the nature of the submission, and clarify if the submission is likely to be based on current or on-going research, a new research project, or synthesize previous findings. Submissions will be peer-reviewed. The deadline for submission proposals is October 16, 2009. The deadline for chapter submissions is February 1, 2010; final drafts of chapter submissions will be sent to the publisher on August 1, 2010.

Manuscript proposals, as well as inquiries regarding further details, should be sent to:  Michael P. Johnson, Ph.D, Department of Public Policy and Public Affairs, University of Massachusetts Boston, Boston, MA 02125-3393

Link to yesterday’s post about the conference.

Mortality rates from infectious disease in the USMortality rate of whooping cough

Mortality rate of measles

Mortality rate of tuberculosis

Mortality caused by scarlet fever in England and Wales (re-drawn from T Mc Keown, 1976)

can OR reduce health disparities?

I am enjoying the Virginia Health Equity Conference.  It’s hard not to believe that operations research can be used to improve public health.

I particularly enjoyed Dr. Howard Frumkin’s keynote about public health and the built environment. His talk was particularly inspiring for operations researcher. We spend almost all of our time in built environments (home, school, work, transportation, parks), and there is an enormous body of research that suggests that our environment is a strong predictor of our health. Our built environment is the result of a series of decisions, some of which can be the result of good operations research and mathematical modeling. A good built environment offers a wide portfolio of public health benefits. Dr. Frumkin listed several opportunities for operations research modeling to improve our built environment (and in turn, public health), including:
• Investigating where to locate schools (perhaps using decision analysis),
• Improving school bus routes that are also safe (Safe Routes), including walking school bus routes (using network design),
• Improving and analyzing transportation networks in urban sprawl regions, which are plagued with low connectivity and low population density (this leads to a host of problems such as reliance on vehicles, low rates of physical exercise, poor access to emergency medical vehicles, etc.).
• Locating trees and green space in urban areas to “cover” poor neighborhoods.

Dr. Frumkin stressed that many of these decisions are generally not made by public health people (perhaps some can be made by operations researchers).

more to come on health care

I apologize for being offline for the past month. Between illnesses, weddings, and the start of the school year, I cut back on blogging and twitter. I finally feel like I’m back into the swing of things.

I am looking forward to the Virginia Health Equity Conference later this week. Although the conference will mainly be attended by medicine and public health people, I hope to blog about health care during the conference. So keep an eye on the blog.  You can follow the conference twitter feed here.

I have been closely following the national debate surrounding health care and health insurance. Although it seems like the issue is mainly a macro-economics issue, I really do think that OR has a lot to offer, particularly in predicting the costs and benefits of treatment and care. But I see so much misinformation (sometimes well-meaning people with the wrong information, and sometimes more sinister ulterior motives) that I easily get discouraged about having a rational, quantitative discussion using OR methodologies.

Last week, I tried discussing some of the health care issues in my class (probability and statistics for engineers). After introducing Bayes rule, I illustrated why it implies that preventive medicine costs so much, in general. I think the discussion backfired. David Brooks explains it better [podcast link here]–when I try, I come off sounding like a an insensitive monster that wants to deny people health care. Really, I just want good numbers to support the debate so we can make good decisions. I’m not sure what the answer is, because I have no idea what the facts are yet. I hope OR is instrumental in providing the facts.

change the drinking age using OR

Underage college students drink. A lot. OR may be able to help.

Ben Fitzpatrick at Loyola Marymount University gave a talk here on Friday about modeling college student drinking habits using mathematical tools. It was entitled “Ecological Systems Modeling of College Drinking,” and it was one of the most engaging talks I have seen in awhile.

Forty-two percent of college students confess to binge drinking, which correlates highly with several forms of violence. Individual interventions are not very successful at curbing drinking problems, but community policies on the aggregate level show promise. Can mathematical modeling be used to predict whether changing the drinking age is a good idea? The premise is that college campuses are relatively homogenous (compared to metropolitan areas), so the resulting model may be useful for policy-making.

Fitzpatrick applied statistical models, dynamical systems, and differential equations that compartmentalized the college population into several groups. His approach uses the fact that people overestimate how frequently their peers engage in risky behaviors (e.g., smoking, drinking). The higher this misperception, the more likely students are to engage in binge drinking. The Social Norms Marketing Research Project provided him with four years of data from 32 schools to estimate misperception. Linear regression was used to estimate some of the parameters needed for Fitzpatrick’s model, and it worked fairly well (R^2 > 0.99 for several parameters).

One model incorporated social interactions (e.g., peer pressure) and social norms/perceptions using a network model (similar to the SIR model used by epidemiologists) to estimate how social interactions could increase or decrease drinking problems. His simulations showed that as drinking misperceptions grow, more students engage in binge drinking (called heavy episodic drinking). I found this particularly interesting, since VCU is always distributing anti-drinking propaganda in the bathrooms (called the Stall Seat Journal, I kid you not), which in essence attempts to reduce misperceptions. Apparently, this is a good strategy for battling underage drinking.

When the drinking age goes down, the “wetness” level in campus goes up, since there are more legal ways to get alcohol. But the Amethyst hypothesis is that misperception goes down when the drinking level goes down (and wetness goes up), since it is easier to directly observe peer drinking activities. Fitzpatrick’s model suggests that results are more sensitive to alcohol availability than to misperception.

This seems to be an important first step in the debate about the drinking age. Before I commit to a policy position, I’d like to see more of these mathematical models to predict what would happen if the drinking age changed. Interestingly, research shows that binge drinking almost completely disappears after college. Maybe we should be trying to get students to finish their degrees in 4 years or less, rather than allowing them to take five or six years to finish?

John McCardle (of the Amethyst initiative and President Emeritus of Middlebury U) appeared on the Colbert Report (3/19/09) to talk about why the current drinking age of 21 is not working. Link.

how to optimize your health care dollars

The Chicago Tribune had an interesting article on how to spend less money on health care. Their advice: use fewer health care resources. The rationale is that the list of things that we know help us live longer is “pretty short.” So quit smoking, exercise, and only spend money on the essentials. Here is what they claim is the list of essentials:

•Skip the annual physical examination. “It’s an unnecessary expense,” said Dr. Ranit Mishori, a family physician who teaches at Georgetown University School of Medicine.

•If you have a cold or an upset stomach, ask if your doctor will do a phone visit. “There may be a charge, but it may be less than even the co-pay for an office visit,” [Dr. Emily] Gottlieb said.

•If your doctor proposes an expensive imaging procedure, such as an MRI for the pain in your knee, ask what it’s for. “If the outcome of the test won’t change the treatment plan, why do it?” Mishori said.

•Instead of a colonoscopy to screen for colorectal cancer, you could opt for an inexpensive test for blood in the stool. “If there’s something wrong, you can follow up with colonoscopy,” Mishori said.

•Consider having a mammogram every two years. “We don’t have any evidence that doing it every year is better than every other year,” [Dr. Ned] Calonge said.

•Ask if you can have a Pap test once every three years. “If you’re over 30 and have had three normal Paps in a row, that shouldn’t be a problem,” said Dr. Linda Hughey Holt, an obstetrician-gynecologist in Skokie. “Only women at increased risk for cervical cancer need annual Paps. And those who have had a total hysterectomy don’t need them at all.”

•Drop your health club membership and walk a mile a day instead. “We know that exercise is very important to prevent diabetes and heart disease,” Gottlieb said. “It’s also important for people who are depressed. But there’s no need for a trainer or a lot of fancy machines.”

•Ask about cheaper equivalents of your prescription drugs. Some chain pharmacies, including Wal-Mart and Target, have $4-a-month prescription plans for the most common generic drugs. You may be able to substitute lovastatin at $4 for Lipitor, which costs about $140.

•For dental work, continue regular checkups to avoid long-term, expensive problems. If you have good oral hygiene and no history of problems, you can consider increasing the intervals for cleanings and X-rays, some experts say. As a general rule, adults usually can delay cosmetic dentistry and orthodontia. But in children, “early orthodontia can save money later,” said Dr. Robert Sandusky of Evanston.

•Talk to your doctor about dropping your cholesterol medication altogether, especially if you’re over 85. The consequences of high cholesterol aren’t felt for 10 or 15 years, Gottlieb said, so pausing or even stopping treatment may not significantly affect your health.

•Insist that your health care providers use the latest operations research innovations so that they can provide the same level of service for less.

OK, so I made up that last item, but wouldn’t that be cool? Many economists have noted that we spend so much for health care in the US because we pay for unnecessary treatment. I don’t know enough to make a comment, but the list looked pretty reasonable to me. What do you think?

OR and the food system

A few weeks ago, I caught a couple minutes of a Michael Pollan interview (the Omnivore’s Dilemma) on Bill Moyers Journal. It was fascinating, but I was tired, so I turned the TV off and went to bed. I just got around to listening to the podcast. Pollan mentions several issues in the interview that have OR implications.

1. Food is cheap in the US. But cheap food is very expensive when taking the whole system into account (food transportation, type II diabetes, other health problems). Looking at the whole system is necessary to understand the costs. Pollan claims that food processing requires 10 calories per calorie consumed(!)
2. Food security is a big issue when our food system is centralized. It is easy to contaminate our food supply when so much food is processed in one location. This is not a new issue, but may have an OR solution. Lawrence Wein talked about the issue at the INFORMS annual meeting (Wein wrote a paper about botulism in the milk supply).
3. Pollan is very critical of the school lunch program since it is used to get rid of food surpluses, which means that students are fed junk food. This really gets me riled up since my oldest child is almost old enough to start school. Pollan advocates spending $1 per student per day to increase the nutritional value in school lunches. Here’s the kicker. As part of the solution, a certain fraction of this extra $1 should be spent within 100 miles of the school in order to meet many social goals (increasing nutritional value of school, reviving the local economy, supporting local agriculture, reducing our dependence on the amount of fossil fuels to transport food all across the country). This sounds like an optimization problem!
4. Pollan proposes a way to measure how healthy out diets are: the fraction of our meals that we cook ourselves. Discuss amongst yourselves. Looking at the fraction of our diet that comes from plants (as opposed to animals) could also a decent measure or looking at the fraction of our diet that is not made of corn by-products (corn syrup) eaten might be OK. On the other hand, a diet of all Fritos is 100% plant-based so it scores high in my first measure, but it is also 100% corn-based, so it scores low in my second measure. I think Pollan has me beat.

Pollan recommends starting a vegetable garden. Apparently during WWII, Eleanor Roosevelt was instrumental in the Victory Gardening program that encouraged people to start vegetable gardens at home. It is widely reported that at the end of WWII, 40% of the US food production came from these 20 million gardens. This is way better than “Freedom Fries.”

I started a garden this year. I built a raised garden bed and planted tomatoes, zucchini, green beans, eggplant, sweet potatoes, hot banana peppers, and butternut squash with various levels of success. It was easy and fun. Digging up sweet potatoes was more fun than I could have imagined (9 small plants yielded about a bushel of sweet potatoes). My cherry tomatoes were so delicious that I ate all of them right off of the plant (a few a day over the course of several weeks). It didn’t generate 40% of my food consumption, but it’s a good start.

Watch the Michael Pollan interview here.