Thursday, October 25, 2012

Screening Tests, Checkups, and Confusion

There is a strong general belief that screening tests and checkups are important elements in improving health for individuals and also good for the greater public.  However a recent comprehensive review published by the Cochrane Library, on the value of general health checkups, questions the value of such regular exams.  At the same time, there are ongoing debates about the specifics of screening tests.  Some of the recent controversies concerning the proper age to begin screening mammography for breast cancer and use of PSA blood tests in screening for Prostate Cancer underscore these debates. Combine all this controversy about specific tests and add in this large study questioning the basic philosophy of regular checkups and screening and you get some massive confusion.  It is reasonable to ask why we argue about these details of screening if, according to the Cochrane study it is all worthless anyway! 

My writing about this started out quite simply as a way of bringing a change in the screening recommendations for Chronic Hepatitis C infection to people’s attention.  In August of this year, the CDC published a recommendation that all people born between the years 1945 and 1965 (aged 47-67) should have a one-time test for chronic Hepatitis C.  This represented an addition to previous recommendations from the CDC for people of all ages who fit certain risk groups, such as a prior history of IV drug abuse or a being a physician or nurse to be screened.  Due to my compulsive nature, I decided to also look at the recommendations of the UnitedStates Preventive Services Task Force (USPSTF).  This independent body under the auspices of the Agency for Health Research and Quality (AHRQ) which is part of the Department of Health and Human Services is an arbiter of recommendations concerning screening tests.  The CDC on the other hand is a part of the Department of Health and Human Services and is not an independent body.  To my surprise I found that the USPSTF had a different recommendation than the CDC.  This was explained in the CDC article published in the Annals of Internal Medicine that recommended the broader screening for Hepatitis C.  It said:
 The U.S. Preventive Services Task Force (USPSTF) and the CDC both issue preventive recommendations using evidence-based methods that include evaluating available data on a topic and drawing conclusions on the basis of the strength of the evidence. However, several differences exist between the organizations, including their affiliation, target audience, and scope. ....... The USPSTF focuses on the primary care setting and provider-patient interactions and considers the harms and benefits (generally, reduced morbidity and mortality) to the patient directly resulting from a given intervention. The CDC has a broader public health focus that includes diverse settings outside of primary care and considers not only the benefits and harms of an intervention but also the potential harms of an absence of public health action and of future transmission of disease.

The USPSTF's HCV screening recommendations and the CDC's birth cohort recommendation are not in direct conflict, and updated USPSTF recommendations are expected within a year. In 2004, the USPSTF found insufficient evidence to recommend for or against HCV screening among high-risk persons (for example, persons who have ever injected drugs) and against routine testing for all asymptomatic adults ( 39). The CDC's recommendation for 1-time HCV testing is only for persons born during 1945 to 1965, not for all adults. The CDC's recommendation is, to a large degree, built upon an intermediate measure (SVR) and its strong association with reductions in HCC and all-cause mortality.

Are you now clear on what screening for Hepatitis C should be done?  So what do you do?  Who do you follow?  Should you follow the recommendations of the CDC, the USPSTF or in the case of other screening recommendations  some other group such as the American Cancer Society or the American Heart Association?  Or should you, following the Cochrane report, just ignore all of them and give up on regular checkups and the screening that accompanies them?

The Cochrane report was comprehensive.    They reviewed 16 studies, 14 of which had outcome data on 182,880 people.  To quote their conclusion,

“General health checks did not reduce morbidity or mortality, neither overall nor for cardiovascular or cancer causes, although the number of new diagnoses was increased…….With the large number of participants and deaths included, the long term follow-up periods used, and considering that cardiovascular and cancer mortality were not reduced, general health chicks are unlikely to be beneficial.” 

What is going on here?  How is an individual to decide what to do?
The reality is that the image of certainty that pervades the public perception of health care is faulty.  Good health care is really riddled with uncertainly and is dependent on a careful assessment of the balance between the risks and benefits of a particular test or therapy for a particular individual at a particular point in time.  While screening tests and procedures and general check-ups are supposed to be independent of those individual variables as they are recommended for broad segments of the population the decision to undergo screening is often not so straightforward.

The definition of screening is “A test or procedure performed for a patient who does not have symptoms, abnormal findings or any past history of a disease in order to detect an unsuspected and undiagnosed disease so that medical treatment can begin.”  The timing and frequency of such a test is usually defined in the screening recommendation, such as the timing for a Hepatitis C test as being once anytime for a person aged 47 to 67 or the timing for mammography being  yearly for women over 40 or 50 depending on which screening recommendation you follow.  They are supposed to be for everyone defined under the screening criteria.  A general checkup as studied in the Cochrane Library review is one type of screening exam and often includes many of the tests and procedures covered under the detailed recommendations.
The reality that is often ignored in all these studies and all these recommendations is that a person often decides to see a physician for a “general checkup” because they are not feeling well, sometimes in a very non-specific and vague way.  Perhaps they are just feeling a bit sluggish or weak; perhaps they have gained or lost some weight.  The good physician then takes a history to try and pull from the patient the information to better define how they are really feeling.  The tests and procedures may then be considered diagnostic and not screening however how they are recorded becomes a function of payment and insurance, not of clinical analysis.   The insurance data bases that many of these studies use for clinical analysis code the exam in the way it is submitted by the health professional and that may be preventive or screening because under today’s rules, that is often paid at a higher rate.  It is hard to say how those very common situations of vague reasons driving the regular exam fit into the data on specific screening tests or on general checkups.
So as for me, I will continue to see my doctor once a year.  As for Hepatitis C, I will have one time testing as I fit into the age category and into the high risk category, especially because while in practice I specialized in gastroenterology and came in contact with large numbers of people with liver disease.  My recommendation to you is to always be an active participant in your care.  Regardless of the statistical benefit of a routine checkup, a good relationship with a doctor who you can call on in time of need is always a good thing.  It may take a general checkup to develop such a relationship.  Determine your own particular risks and your own values and beliefs in making decisions about your own care including decisions about screening.   Then make your own decision based on all of the facts.  What makes sense for a population may or may not make sense for you as an individual at a particular point in time.