The US Preventive Services Task Force (USPSTF) 2009 Mammography Screening Recommendations Were Understandably Ignored by the Medical Establishment and Its Patients

01 May 2013

Citation — to study of medical establishment’s response to the 2009 USPSTF mammography screening guidelines

Lydia E. Pace, Yulei He, and Nancy L. Keating, Trends in mammography screening rates after publication of the 2009 US Preventive Services Task Force recommendations, Cancer, DOI: 10.1002/cncr.28105 (early online publication, 19 April 2013)

The medical establishment frequently ignores science-based medicine — but there are times when the failure to act on supposedly scientific recommendations is understandable

For example, you may recall that:

In November 2009, the US Preventive Services Task Force (USPSTF) issued new recommendations regarding mammography screening.

The Task Force recommended against routine screening for women ages 40 to 49 years and recommended biennial screening for women ages 50 to74 years.

The recommendations met great controversy in mass media and medical literature . . . .

© 2013 Lydia E. Pace, Yulei He, and Nancy L. Keating, Trends in mammography screening rates after publication of the 2009 US Preventive Services Task Force recommendations, Cancer, DOI: 10.1002/cncr.28105 (early online publication, 19 April 2013) (at Abstract) (paragraph split)

My wife — currently Chief of Medical Education and Training at a U.S. Air Force base — wrote her master’s thesis on the breast cancer screening controversy after the Preventive Services Task Force recommendations were issued.

Interested in the subject myself (due to abbreviated backgrounds in both medicine and law), I reviewed the USPSTF recommendations and existing medical data just after the USPSTF recommendations were published. I forecast that nothing was going to come of them. The medical establishment’s financial and malpractice self-interest, combined with the public’s fear of cancer, would militate against implementing the USPSTF’s (arguably valid) common sense.

The above study demonstrates that the prediction was warranted.

Study’s methods

From the abstract:

The objective of this study was to determine whether the 2009 USPSTF recommendations led to changes in screening rates among women ages 40 to 49 years and ages 50 to 74 years.

The authors performed cross-sectional assessments of mammography screening in 2005, 2008, and 2011 using data from the National Health Interview Survey, a nationally representative, in-person, household survey of the civilian, noninstitutionalized US population.

In total, 27,829 women ages ≥40 years responded to the 2005, 2008, or 2011 surveys and reported about their mammography use.

The primary outcome assessed was self-reported mammography screening in the past year.

There is nothing methodologically especially suspect with this approach. The Survey is sponsored by the Centers for Disease Control and Prevention, done in person, and based on Census data.

For a generalized overview of the study’s kind, there is little reason to suspect that the Survey’s figures would grossly depart from those that the USPSTF had used in generating its recommendations.

Findings

Again, from the abstract:

When adjusted for race, income, education level, insurance, and immigration status, mammography rates increased slightly from 2008 to 2011 (from 51.9% to 53.6%; P = .07) and did not decline within any age group.

Among women ages 40 to 49 years, screening rates were 46.1% in 2008 and 47.5% in 2011 (P = 0.38).

For women ages 50 to 74, screening rates were 57.2 in 2008 and 59.1 in 2011 (P = 0.09).

The “P” values cited above will mean something only to scientifically or statistically trained readers. P values are measures of statistical validity. Those above are not particularly persuasive — especially so for the 40-49 year old screening range. But given the nature of how this data had to be collected, they are probably good enough for rendering questionable the hypothesis that the USPSTF recommendations actually accomplished a change in medical practice — or alternatively, lending credence to the null hypothesis that the recommendations had no effect.

Why should we care whether the recommendations were adopted in clinical practice — people are free to do what they want, aren’t they?

Yes, but there are significant financial and false positive costs that accompany medical screenings that have been cast with arguably too wide a net. Which is exactly what the Preventive Services Task Force was driving at.

These avoidable costs somewhat parallel those typical of PSA screening for men’s prostate cancer — which is another situation in which biological ambiguity combines with individualized fear to create a demand for arguably unnecessary cancer screening in patients who are, realistically speaking, subject to only low or average risk for the disease.

Reluctance to forgo routine screenings in low and average risk, 40-49 year patients is completely understandable

For years, the medical infrastructure has touted the benefits of catching cancer early.

And most people overestimate the efficacy of breast and prostate cancer screening. They exaggerate the likelihood that cancers will be detected early. And they underestimate the probability that they will become victim of false positives and a subsequently long voyage down a road of often debilitating, unnecessary medical interventions. Medical providers do the same.

Most of us fail to see these drawbacks because we operate in a social and medical culture that ignores the variety of costs associated with giving statistically low-yield medical screenings, as well as the worry and subsequent exploratory interventions that result from false positives.

Because insurance pays most of the time, we are not especially cautious in signing up for whatever the (often admittedly self-interested) medical establishment has placed on the Carte du Jour.

I am not attacking medical providers

Medical providers are in a difficult position.

They want to do what is best for the individual patient, not for the health system generally. And most providers would take it personally, if a patient died because the provider had not screened for the illness that subsequently killed the patient.

Statistical evidence against the wisdom of the routine public health screening of low risk patients does not make up for the sadness (and possible malpractice litigation) of having lost someone who could have been saved.

And that is where the USPSTF’s recommendations were inadequately sold — and why they (apparently) did not work to change clinical practice.

Where the USPSTF recommendations fell down

To change behavior, one has to make a strong case for change. The USPSTF did not.

Below is the critical section of what the Task Force wrote. I have underlined its critically important elements:

In 2002, the USPSTF concluded that there was fair evidence that mammography screening every 12 to 33 months could significantly reduce breast cancer mortality.

The evidence was strongest for women aged 50 to 69 years, with weaker evidence supporting mammography screening for women aged 40 to 49 years.

Since that recommendation, 1 new trial and updated data from an older study have been published that specifically address screening in women in the younger age group.

These findings were combined in an updated meta-analysis, which resulted in an RR [relative risk] for breast cancer death of 0.85 . . . and a number needed to invite for screening of 1904 . . . to prevent 1 breast cancer death in women aged 39 to 49 years.

A meta-analysis of 6 trials among women aged 50 to 59 years and 2 trials among women aged 60 to 69 years provided pooled RRs [relative risks] for breast cancer death in the screened group of 0.86 . . . number needed to invite, 1339 . . . and 0.68 . . . number needed to invite, 377 . . . respectively.

Only 1 study provided data on women older than 70 years, yielding an RR [relative risk] of 1.12 . . . although an RR of 0.78 . . . was found for women aged 65 to 74 years by combining the results of 2 studies used in the 2002 review.

A decision analysis performed for the USPSTF projected that biennial screening produced 70% to 99% of the benefit of annual screening, with a significant reduction in the number of mammograms required and therefore a decreased risk for harms.

Screening between the ages of 50 and 69 years produced a projected 17% . . . reduction in mortality (compared with no screening), whereas extending the age range produced only minor improvements (additional 3% reduction from starting at age 40 years and 7% from extending to age 79 years) (8).

For women aged 40 to 49 years, the USPSTF had moderate certainty that the net benefits [of mammographic screening] were small.

U.S. Preventive Services Task Force, Screening for Breast Cancer — Recommendation Statement (December 2009) (at section entitled, Estimate of Magnitude of Net Benefit) (paragraphs split)

Think about how unpersuasive the above language is

As a medical provider, am I really going to quibble that I have to screen 1,900 patients to potentially save 1 life?

Will I be dissuaded from recommending routine mammographies to low and average risk 40-49 year olds because screening potentially saves only 3 percent of them?

And will I be persuaded that biennial screening is equivalent to annual screening for older patients because it delivers somewhere between 70 and 99 percent of the benefit of scanning each year?

I don’t think so. Especially when my patient’s insurance company has agreed to pay for the mammogram and (presumably) whatever becomes necessary after suspicious findings arise.

The basic problem is simple. No medical provider is going to write off 3 percent of her younger patients. And none is going to voluntarily take a chance that she might be writing off as many as 30 percent of her older patients by adopting lessened screening standards.

That said — the USPSTF’s position might actually have been in the nation’s best interest

With health care eating up ridiculous amounts of the Gross Domestic Product, Americans should be looking for ways to reduce scientifically questionable medical screenings and procedures — in situations in which they are statistically or financially unwarranted, when viewed as a public health policy measure.

Notice the implied distinction in that last sentence. Public health morality is different than medical provider morality. The former is legitimately concerned with the public impact of medical costs. The latter is much less so, unless the individual patient has volunteered that concern.

The moral? — It’s all about money, and in ways that one does not immediately suspect

Only when insurance providers get on board with the USPSTF’s perspective will a clinical paradigm shift take place.

My guess is that when women have to pay for screens that insurance will not cover, they will be more amenable to the USPSTF’s possibly valid logic.

But until that day, no reasonable medical provider is going to voluntarily subject herself to assisting in killing off a small, but noticeable number of her patients.

The USPSTF’s 2009 mammography recommendations did not have a prayer of succeeding in a system that is constructed the way that ours currently is. That should have been obvious from the “git go”.

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The US Preventive Services Task Force (USPSTF) 2009 Mammography Screening Recommendations Were Understandably Ignored by the Medical Establishment and Its Patients