Cancer epidemiology 101

I've had many Twitter conversations with cancer screening advocates who fear that the U.S. Preventive Services Task Force's "D" (don't do it) recommendation against PSA-based screening for prostate cancer will lead to a dramatic spike in prostate cancer deaths as primary care physicians screen more selectively, or perhaps stop screening at all. I seriously doubt these apocalyptic forecasts (for one thing, prostate cancer causes only 3% of deaths in men, and the decline in the U.S. prostate cancer mortality rate since 1990 hasn't had any appreciable effect on overall life expectancy). However, I recognize that reasonable people disagree with my review and the USPSTF's interpretation of the evidence. The American Cancer Society, for example, continues to support screening if men are adequately informed of the known risks and uncertain benefits. But it's one thing to argue from evidence, and quite another to argue from ignorance. Many of the tweets I've seen from urologists, unfortunately, represent the latter.

When I went to medical school, biostatistics and epidemiology was the course that no one took seriously. Things have changed for the better over the years - today I teach a rigorous course in evidence-based medicine and population health at Georgetown University School of Medicine - but there's still an appalling lack of basic knowledge about these topics among practicing physicians of all specialties. Below are a few key concepts in cancer epidemiology that anyone should understand before getting into a dispute about the value of prostate cancer screening.

Lead-time bias - "Prostate cancer survival has improved since we started PSA screening, so screening must work!" The first clause of this sentence is absolutely true: in the 1970s, about 70 percent of men diagnosed with prostate cancer were still alive 5 years after diagnosis, while today that figure is closer to 99 percent. The second clause could be true, but does not invariably follow from the first. By finding prostate cancers in men long before they become symptomatic (if they ever become symptomatic), screening advances the time of diagnosis, but could have no impact on mortality. In other words, 5-year survival always increases when a screening test is implemented, but its effect might only be giving patients an earlier cancer diagnosis without affecting their disease course. See chest x-ray screening for lung cancer (which was unfortunately a common practice for years) for an example of this phenomenon.

A variation on the above statement is the observation made by older urologists that "Before PSA testing, we used to see men with prostate cancer only when they came in with metastatic disease; today we see them with much less advanced tumors so that they can be cured." Much of this clinical experience reflects the effect of lead time, as well as overdiagnosis of cancer that didn't need to be found in the first place. In the words of urologic oncologist Willet Whitmore, "For a patient with prostate cancer, if treatment for cure is necessary, is it possible? If possible, is it necessary?"

Association does not equal causation - "Prostate cancer mortality has declined by 30 percent since 1990, which must be due to PSA screening." It's tempting to make sweeping conclusions based on observational data - the press has been doing this forever, linking caffeine use to cancer today, then reversing itself when a new headline is needed tomorrow. It's certainly possible that some of the decline in mortality is due to screening, but it's just as likely that some other factor is responsible. For example, men who smoke are less likely then male non-smokers to die from prostate cancer. Does that mean that tobacco use has a protective effect? Of course not; these men are dying prematurely from heart attacks and chronic obstructive pulmonary disease, and therefore not dying of prostate cancer. Also, the temporal association between the mortality decline and the PSA screening doesn't make any sense, since the only randomized trial to show that PSA screening reduces prostate cancer mortality (more on this later) found that it takes at least 9 years to do so. Since PSA screening was not widespread in the U.S. until the early 1990s, any benefit of screening wouldn't have changed the mortality statistics until 2000. But that's not what happened.

The most favorable study represents "the truth" - "Prostate cancer screening reduces prostate cancer mortality by 20 percent." If you only speak to urologists, you might come away thinking that there's only been one randomized trial of PSA screening: the European Randomized Study of Screening for Prostate Cancer (ERSPC), which reported this result in 2009 and again in 2012 after 11 years of follow-up. The usual description of the ERSPC as a single "trial" is problematic (it's actually a combined analysis of screening results from 7 European countries), but even allowing for that, it's only one of 5 randomized trials of screening, and (guess what?) the only one of the 5 to show a benefit.

In the old days, the process of writing reviews and guidelines went as follows: write up recommendations that you already know to be correct from clinical experience, then go to the literature to select evidence that supports your positions. A less biased approach is to evaluate all of the available evidence, regardless of one's preexisting biases, which is what my colleagues and I did and what independent reviewers did for the both the Cochrane Collaboration and BMJ. Here's what the Cochrane reviewers concluded: "Prostate cancer screening did not significantly decrease all-cause or prostate cancer-specific mortality in a combined meta-analysis of five RCTs."

Specialist-authored guidelines are superior to generalist-authored guidelines - "The USPSTF guidelines are invalid because there were no urologists on the panel." Let's put aside for the moment the fact that more prostate cancer diagnoses invariably lead to more business for urologists, and that guidelines authored by specialty societies are of lower quality than those authored by generalists. Dismissing the USPSTF recommendation on the basis of its primary care membership is still nonsense, pure and simple. The vast majority of prostate cancer screening occurs in primary care settings, and therefore primary care clinicians are the most appropriate experts to evaluate and weigh the evidence about screening. (The same can be said about mammography guidelines and radiologists.) Several urologists were, of course, consulted at multiple stages during and after the writing of our evidence review to make sure that no important studies were missed.

As I've said, I welcome debates with well-informed advocates of PSA screening, who tend to view this imperfect test as a glass half-full rather than half-empty (or shattered beyond repair). For the less-informed, I get it that you don't have time to go back to medical school for remedial epidemiology lessons. So consider this post your Cliff's Notes.

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This post originally appeared on Common Sense Family Doctor on December 12, 2012.

Does Meaningful Use provide meaningful benefits to patients?

The ambitious federal effort to improve the quality of patient care in the U.S. by providing up to $30 billion in incentives to physicians who demonstrate "meaningful use" of certified electronic health records (EHRs) has now entered a new stage, aptly described in a recent Family Practice Management article as either a "second wave or a tsunami," depending on one's point of view. Officials at the Centers for Medicare and Medicaid Services believe that meaningful use will ultimately provide meaningful benefits to patients. However, this hypothesis has largely remained untested. In an editorial two years ago, I summed up the state of the science as follows: "the evidence is far from conclusive that EHRs and CDSSs [clinical decision support systems] improve preventive care processes and outcomes in primary care settings."

A research letter published last week in JAMA Internal Medicine examined the association of being a "meaningful user" with performance on 7 quality measures for hypertension, diabetes mellitus, coronary artery disease, asthma, and depression during a 90-day reporting period in the fall of 2012. 540 meaningful users were compared to 318 other outpatient physicians using the same EHR in Brigham and Women's Hospital-affiliated practices. Meaningful users performed slightly better in controlling cholesterol levels and blood pressure, worse in treating asthma and depression, and the same on the 3 remaining measures, compared to non-meaningful users.

Although these preliminary findings are unlikely to affect plans to move ahead with Stages 2 and 3 of meaningful use over the next few years, they remind family physicians of the real goals of practice transformation, and caution us not to conflate meeting meaningful use targets with making patients' lives longer or healthier.

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This post first appeared on the AFP Community Blog.

Lung cancer screening: understanding "relative risk"

Enthusiasm for lung cancer screening has never been higher, following publication of the National Lung Screening Trial (NLST) report that heavy smokers who underwent 3 rounds of low-dose computed tomography (CT) screening were 20 percent less likely to die from lung cancer compared to a similar group that was screened with chest x-rays (a "placebo" intervention that another study found to be ineffective). The U.S. Preventive Service's Task Force's decision to recommend annual lung cancer screening in up to 9 million persons between ages 55 to 80 will almost certainly result in expanded use of this new clinical preventive service.

In a previous post, I offered a few reasons for eligible patients to consider not getting screened for lung cancer: 1) the risk of developing cancer from the CT scan itself; 2) high rates of false positive tests; 3) overdiagnosis and overtreatment; 4) incidental findings that could lead to additional, likely unnecessary, diagnostic procedures. I concede, however, that reasonable people might conclude that these potential harms are outweighed by the benefit of reducing one's risk of dying from lung cancer by one-fifth, especially if the patient in question has already quit smoking.

The next critical question that needs to be asked is: one-fifth of what?

The more you smoke, the longer you smoke, and the older you are, the greater your risk of dying from lung cancer. Men are also slightly more likely to die from lung cancer than women. The "average" participant in the NLST was a 62 year-old man who had smoked one and a half packs of cigarettes per day for 35 years. In the absence of screening, 20 out of 1000 men like this would die from lung cancer over the next 6 years. Taking away 20 percent of that risk with screening (20 minus 4) reduces his risk of lung cancer death to 16 out of 1000. Stated another way, about 250 people would need to be screened to prevent 1 death from lung cancer over 6 years, which, compared to other screening tests, is a pretty impressive figure. (In contrast, nearly 2000 women in their 40s need to be screened with mammograms to prevent one breast cancer death over a similar time period.)

As Drs. Peter Bach and Michael Gould pointed out in the Annals of Internal Medicine, however, few people currently being offered lung cancer screening have a risk of lung cancer death that resembles the average NLST participant. A 55 year-old woman who just kicked her 1 pack-per-day, 30-year smoking habit has only a 4 in 1000 risk of death from lung cancer in the next 6 years. Taking away 20 percent of that risk (4 - 0.8) drops it to about 3 in 1000. More than 1200 patients like this woman would need to be screened to prevent 1 death from lung cancer. And some hospitals across the U.S. are offering lung cancer screening to younger smokers at even lower risk, translating to numbers needed to screen of 35,000 or more to prevent one lung cancer death - a benefit that could easily be outweighed by all of the potential harms of screening.

Their conclusion: "The underlying chance that a person will benefit from CT screening should be considered when counseling patients about the potential benefits of being screening." Too often when physicians offer a screening test or other intervention, we tend to quote the impressive-sounding reduction in relative risk without providing patients with information about their baseline risk, or what their risk would be without it. This isn't likely to change any time soon. To make a fully informed medical decision, whenever a doctor says, "Test X will reduce your risk of disease X (or death from disease X) by 20 percent," patients should always ask, "20 percent of what"?

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A slightly different version of this post originally appeared on Common Sense Family Doctor on August 15, 2012.

Health insurance is not health care

The title of this post is not original. I borrowed it from LA County Department of Health Services Director Mitchell Katz's JAMA Internal Medicine editorial about problems with ensuring access to health care for Medicaid recipients whose cheap public insurance usually doesn't even pay doctors enough to recoup costs of care, let alone earn a living. But somehow, during the impassioned political debates that preceded Obamacare, the botched rollout of Healthcare.gov, and the pointless debate about how many people got (or lost) health insurance from the Affordable Care Act, it's easy to omit this critical point, which Dr. Katz makes clearly: "Health insurance is a financial mechanism for paying for health care. It is not the care itself, or even a guarantee of that care."

Most of my colleagues would say that health insurance makes it easier for people, especially those with limited means, to access health care. I'm not sure I agree (especially for inexpensive primary care services), but it's easy to see why they feel that way. Health care spending makes up nearly 20 percent of economic spending in the U.S. On an individual level, what do you spend 20 percent of your income on? Housing? Transportation? Food? Unless you're exceptionally wealthy, it's hard to imagine finding another 20 percent to spend on health care, especially expensive care related to a catastrophe, such as a car accident or heart attack.

I believe that health insurance should be a mandatory financial mechanism for paying for unexpected, catastrophic health expenses, just as fire insurance will pay if my house burns down or flood insurance will pay if a hospital in a low-lying area is devastated by a hurricane. On the other hand, health insurance is a grossly inefficient mechanism for paying for expected care - that is, primary and preventive care.

Think about how insurance works when you visit a typical family physician. Depending on your plan, you may pay a fixed co-payment, or pay nothing. You receive medical services recommended by your doctor without knowing (or asking) how much any of it costs. What your doctor charges for these services has very little relevance to you and even less relevance to the insurance company, which will pay whatever price it has pre-negotiated for its members. This is the way health care financing has worked for so long that it's difficult to step back and realize how stupid it is.

Let's substitute food for health care and imagine there is such a thing as "food insurance." You enter the grocery store and pay a fixed co-payment, or pay nothing. You choose food items recommended by your grocer without knowing (or asking) how much any of it costs. What your grocer charges for the contents of your shopping cart has very little relevance to you and even less relevance to the food insurance company, which will pay whatever price it has pre-negotiated for its members. Does this sound like a good way to make food more affordable? When people are poor enough that they can't afford to buy food, governments don't provide them with food insurance, but food stamps (or supplemental nutritional assistance) so that they can purchase food directly. So it should be with health care.

A couple of years ago, I blogged about a friend who had the misfortune to need an appendectomy while he was uninsured. You might assume that after that experience my friend, whose name is Jose Padilla, would ridicule "consumer-driven health care" and be all for insurance paying for every single medical expense, no matter how minor. You would be wrong. Jose, who is now a candidate for Congress from the state of Nevada, told me recently that "insurance should be there for those situations where you don't have the time to negotiate and/or the cost would bankrupt you." In his opinion, the biggest problem with health care is that the prices are too high. The prices are too high because there is no price transparency (imagine how hard it would be to shop for groceries when you weren't told what the food cost until a bill arrived in the mail weeks or months later), and there is no price transparency because someone else other than the patient is paying most of the bills.

As Jose's health care platform observes, "the health care industry [is] one of the only U.S. industries where the addition of new technologies causes an increase in prices." Why? Because medical prices will increase as long as someone else - your employer, your government, Obamacare, whomever - is willing to pay them. Why else would ophthalmologist Salomon Melgen inject patients' eyes with a very expensive drug (Lucentis) instead of a much cheaper equivalent drug (Avastin)? Because he could bill Medicare Part B $11.8 million for those shots in 2012 instead of $500,000. In fact, 879 of the doctors who billed Medicare at least $1 million that year were ophthalmologists using Lucentis, according to the Washington Post. If you want to know how much money your doctor received from Medicare in 2012, click here. (I received $3,201.) Kudos to the Centers for Medicare and Medicaid Services for making this information public, and for reminding us of the disconnect between having health insurance and receiving health care.

Direct primary care called one of health care's "big ideas"

A Graham Center Policy One-Pager in the April 1st issue of American Family Physician uses historical data to project the effect of the 2010 Primary Care Residency Expansion Program (PCRE). By its conclusion in 2015, the PCRE program will have funded an additional 900 residency trainees in family medicine, general internal medicine, and general pediatrics above the current cap on Medicare-supported residency positions. Based on historical trends, though, only 39 percent of internists in these particular programs will end up practicing primary care, compared to 51 percent of pediatricians and 92 percent of family physicians. As a result, only about two-thirds of these residents are likely to enter the primary care workforce. Of course, 600 new primary care physicians are better than none, but at an estimated $100,000 per year per resident, this well-intentioned federal program will also spend $90 million to train additional internal medicine and pediatric subspecialists that are already in plentiful supply.

In addition to modest programs like PCRE, big ideas are needed to transform U.S. health care to a patient-centered system, grounded in primary care, that delivers the best possible health outcomes for all. Corey Fogleman, MD and Thomas Gates, MD propose several in a recent article in the Journal of Lancaster General Hospital, including:

1) Making medical school free, and providing residency training stipends only to graduates who choose primary care programs
2) Direct primary care: "eliminating the middle-man of third-party insurance"
3) Single payer systems providing universal insurance coverage on the state level

Of these three big ideas, direct primary care (discussed in a previous guest post on Common Sense Family Doctor) appears to face the fewest political and logistical obstacles and is rapidly becoming a reality in communities across the country. Drs. Fogleman and Gates observe:

Advocates of this approach point out that insurance is meant for large unexpected expenses, while expenses for primary care are relatively modest and predictable. It makes little sense to pay for these through an insurance model, any more than it would make sense to buy auto insurance to protect from the cost of an oil change or new tires. Instead, patients in direct primary care contract directly with a primary care provider for access to a broad range of office-based primary care services, in return for a monthly or annual retainer fee.

Unlike “concierge medicine,” the fee is modest (usually on the order of $500-$1000 per year), and can complement high-deductible or catastrophic insurance (which would cover large and unexpected expenses like hospitalization). An element of competition safeguards consumers: practices that don’t deliver quality and accessible primary care will quickly lose patients.

A collection of articles about direct primary care and membership-based practices is available on the Family Practice Management website. Clinicians and policymakers interested in learning more about direct primary care should also consider attending the second Direct Primary Care National Summit in June (registration code: MDUADPC).

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A slightly different version of this post first appeared on the AFP Community Blog.

"Free" health screenings have hidden costs

Last week, I spoke to a class of undergraduates about the benefits, harms and politics of screening smokers for lung cancer using low-dose CT scans. Afterwards, a student asked how I felt about the Affordable Care Act's requirement that Medicare and private insurers cover U.S. Preventive Services Task Force "A" and "B" recommended screening tests and other preventive services without co-payments or deductibles, making them free at the point of care.

I admitted that I have mixed feelings. On one hand, some studies have found that even small out-of-pocket payments make patients less likely to receive recommended health screenings or counseling. On the other, it isn't clear why this particular set of services for healthy people (which include contraceptives classified as "pregnancy prevention") deserve to be valued more than medical interventions for people who actually suffer from chronic illnesses. The chance that a 50 year-old woman at average risk for breast cancer will have her life extended by a screening mammogram is around 1 in 1000; the chance that a 50 year-old woman with diabetes and high blood pressure will have her life extended by taking fitness classes and anti-hypertensive drugs is around 1 in 20. The healthy person receives a service for free; the ill person does not. And, as I wrote in a blog post shortly after the 2012 Presidential election, that mammogram isn't really free:

Thanks to the ACA / Congressional Democrats / President Obama, a typical political ad will say, women can now get free mammograms, Pap smears, cholesterol tests, and birth control pills! Isn't that great? This kind of ad is misleading because none of the preventive health services defined by the bill have suddenly become free. In fact, some cost hundreds or even thousands of dollars. Instead, the costs of these services have just been shifted - into higher insurance premiums, on to an employer, or to the federal government (and therefore the individual taxpayer or an international investor that holds some portion of the U.S.'s $16 trillion national debt).

A perceptive commentary in this week's JAMA by Drs. Joann Elmore and Barry Kramer offered more reasons to doubt the wisdom of mandating that marginally beneficial preventive services be provided for free:

With the goal of improving access to preventive services and medical screening, the ACA offers free screening mammography to women. However, women often pay for the consequences of screening, even if the screening examination is free. Women bear not only financial charges but also important human costs. Screening mammography can trigger recalls for more testing, biopsies, mastectomies, radiation, systemic therapy, days off work, and debt related to health care costs. These byproducts of screening can lead to adverse financial consequences and personal harm.

Two years ago, I bought a color printer for under $50 (practically free!) for my home office. It printed pages excruciatingly slowly, had a tendency to jam and leak toner, and sets of replacement cartridges came to $75 every other month. Several weeks ago it quit printing any documents that required black ink. After spending hours trying unsuccessfully to troubleshoot the problem, I paid five times as much for a new printer, and so far it's worked like a dream.

Do I provide mammograms and other USPSTF-recommended "free" screening tests to my patients? Of course I do. But I also caution them not to be deceived by the sticker prices for these services and exaggerated claims about their benefits, and to consider more than up-front costs in determining personal health values, as they would in making decisions about the value of any other service that costs money.