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PC Editorial DECEMBER 2005

Evidence-based Clinical Guidelines Are Grand—or Are They?

Robert B. Taylor, MD

My patient is a 67-year-old married woman who is monogamously—albeit infrequently—sexually active. Over the past decade, she has had three Papanicolaou (Pap) smears with normal results, and she is otherwise quite healthy as well. She asks me, –Doctor, can I quit having Pap smears? I read in a magazine that the guidelines say I donêt need one ever again.”

Over the past decade or so, clinical practice guidelines (CPGs) have come to be viewed as important building blocks for modern medical practice. Based on methodologically sound studies, CPGs direct physicians day by day in the practice of evidence-based medicine (EBM) in offices and hospitals across the country.

Therefore, in an effort to be an up-to-date, EBM-grounded physician, I went to the source—ie, the National Guideline Clearinghouse (NGC).1 Searching with the key words –cervical cancer screening,” I found 58 related guidelines. I tried again, using –Pap smear after age 65 years”; this pared the results to 25 guidelines. I began to see that there are many –official” opinions on this topic.

Do these opinions agree? The US Preventive Services Task Force (USPSTF) concludes that routinely screening women aged > 65 years for cervical cancer—if they have had adequate recent screening with normal findings and no other risk factors—merits a –D” recommendation. That is, the potential harms of screening are likely to exceed the benefits.2

This sounds reasonable. Just to be thorough, though, I checked the recommendations of the American Cancer Society (ACS). The ACS seems to agree with the USPSTF, but their cut-off is 70 years of age, not 65.3 And then there is the American College of Obstetricians and Gynecologists, which courageously recommends that physicians make decisions to stop screening on an individual basis.4

My research was not yielding a clear-cut answer, but it did prompt me to dig a little deeper into clinical guidelines. I returned to the NGC Web site to find out who actually promulgates these guidelines. Qualified organizations include academic institutions (such as my own school, the Oregon Health & Sciences University), federal agencies (eg, the US Centers for Disease Control and Prevention), and disease-specific societies (eg, the ACS). This seems sensible, but wait—CPG guidelines can also be created by medical specialty societies; private, for-profit organizations; and medical/ pharmaceutical manufacturers.5 Surely, this would invite bias, though. For instance, might an organization that depends on finding many new cases of a disease (eg, surgical or chemotherapy candidates) have a vested interest in maximum screening, even if evidence that screening improves the quality or length of life is inconclusive?

However, CPGs are by definition based on evidence, right? When I reviewed the methods used to assess the evidence and formulate the recommendations, I found that the words “expert panel” could apply to committees, Delphi panels, and consensus development conferences.5 To me, this is beginning to sound suspiciously like “good old boys sitting around a table.”

The CPGs are worthwhile if they can help me make a sound clinical recommendation to my patient. Also, if the worst happens, the guidelines should help protect me in court. Much of medicine is betting on the numerical odds of something happening or not happening. This means that, occasionally, a patient and/or physician will lose. I could follow the USPSTF guidelines and stop performing Pap tests for this patient, and she could develop invasive cervical cancer next year and decide to file a lawsuit.

I would urge all physicians to read a commentary in the Journal of the American Medical Association by Daniel Merenstein, MD, that describes his experience with using preventive CPGs in practice.6 In 1999, while a family medicine resident, Dr Merenstein discussed the pros and cons of screening with prostate-specific antigen with a –highly educated” 53-year-old man. (Does this sound a little like my current Pap smear dilemma?) The USPSTF gives such screening an –I” recommendation—ie, insufficient evidence to recommend for or against testing. They decided not to test. The patient was subsequently found to have prostate cancer, and filed a lawsuit.6 In court, jurors considered 15 separate prostate cancer screening guidelines and conflicting expert testimony. Dr Merenstein was ultimately exonerated, but his residency training program was found liable for $1 million.

So what about guidelines? There are lots of them—often too many to be practical. What the physician needs to know is sometimes difficult to find. Each CPG is focused on a single clinical problem, as though the patient has only one disease; I wish life were that simple. And although the CPGs appear to be grounded in –best evidence,” they are created by panels of experts with their own viewpoints and biases.

On the other hand, CPGs represent medicineês current best effort to base clinical decisions on actual evidence. As physicians, we consider CPGs when making decisions, but we reserve the prerogative to temper them with clinical judgment. In instances of alleged clinical negligence, guidelines do not serve as legal standards for clinical care, but they do provide courts with a benchmark for judging clinical conduct.7 For now, CPGs are one more implement in our practice toolbox, to be used—with care—when appropriate.

As for my patient, we decided to follow the USPSTF recommendation. We jointly agreed that—unless something changes—she has had her last Pap smear. She was pleased.

Robert B. Taylor, MD Editorial Advisory Board Member

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References

1. National Guideline Clearinghouse Web site. Available at: http://www. guidelines.gov. Accessed November 6, 2005.
2. US Preventive Services Task Force. Screening for cervical cancer: recommendations and rationale [Agency for Healthcare Research and Quality Web site]. Available at: http://www.ahrq.gov/clinic /3rduspstf/cervcan/cervcanrr.pdf. Accessed November 6, 2005.
3. New cervical cancer early detection guidelines released. American Cancer Society Web site. Available at: http://www.cancer.org/docroot/NWS/content/NWS_1_1x_New_Cervical_Cancer_Early_Detection_Guidelines_Released.asp. Accessed November 6, 2005.
4. ACOG Committee on Practice Bulletins. ACOG Practice Bulletin: clinical management guidelines for obstetrician-gynecologists. Number 45, August 2003. Cervical cytology screening (replaces committee opinion 152, March 1995). Obstet Gynecol. 2003; 102(2):417-427.
5. NGC browse—organizations. National Guideline Clearinghouse Web site. Available at: http://www.guideline.gov/browse/browseorgs.aspx. Accessed November 6, 2005.
6. Merenstein D. A piece of my mind. Winners and losers. JAMA. 2004; 291(1):15-16.
7. Hurwitz B. How does evidence based guidance influence determinations of medical negligence? BMJ. 2004;329(7473): 1024-1028.

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