So it is time for your « Annual” or ”Check up”. What does this actually mean anymore? Does an annual physical exam provide a health benefit? In fact, the Cochrane Collaboration asked this question and their findings confirmed what most physicians know. Marketing has oversold the concept. These checkups do little to prevent disease in otherwise healthy people and for many, introduce invasive and unnecessary blood tests that in themselves can lead to false positive results.
What do we do instead? We try to use the best available evidence to tailor our Periodic Health Evaluation (PHE) based on age-related health risks. For people interested in what they can expect when they visit their family doctor for a PHE, I would recommend an app called ePSS (iOS and Android) produced by the US Department of Health and Human Services that amalgamates all the available evidence for most of the common procedures and tests. It recommends screening and blood tests that have a demonstrated health benefit. It is one step towards personalized medicine.
Screening is an important feature of the PHE. It can include PAP tests, blood pressure, weight, blood tests for the detection of diabetes and heart disease risk, mammograms, and bone density evaluations among others. So in terms if screening, what constitutes a proper screening test? :
- The condition being screened for is important in terms of public health – for example, it is serious and/or affects large numbers of people
- There is a recognizable early stage of the condition
- There is an effective and acceptable treatment for the condition, so screening is likely to make a difference to its outcome
- There is a valid and reliable test for the condition that is acceptable to people being offered screening
- The screening programme is of good quality and cost-effective in the setting in which it is to be offered
- The information provided to people is unbiased; based on good evidence; and clear about possible harms (eg, overdiagnosis leading to over-treatment) as well as potential benefits
- The invitation for screening is not coercive – that is, it indicates it is reasonable to decline
- The chance of physical or psychological harm to those offered screening is likely to be less than the chance of benefit
- There are adequate facilities for the diagnosis and treatment of abnormalities detected by screening
* This list is copied from Testing Treatments Interactive
There is a frequently recommended cancer screening test for women (I want to leave it unidentified until later in this article to remove affect bias). I request them based on the available evidence and recommendations as well as the patient’s family and personal medical history. This is what the Cochrane Collaboration had to say about it:
« For every 2000 women invited for screening throughout 10 years, one will have her life prolonged and 10 healthy women, who would not have been diagnosed if there had not been screening, will be treated unnecessarily. Furthermore, more than 200 women will experience important psychological distress for many months because of false positive findings. It is thus not clear whether screening does more good than harm.”
Another review produced these results:
For every 1000 40-year-old women undergoing this annual test for ten years:
- 0.1 to 1.6 avoid dying from cancer
- 510-690 will have a false positive and of whom 60-80 of will undergo a biopsy
- Overdiagnosis of cancer occurs in as any as 11 women leading to needless surgery, radiation, and chemotherapy
For every 1000 50-year-old women undergoing this annual test for ten years:
- 0.3 to 3.2 avoid dying from cancer
- 490-670 will have a false positive and of whom 70-100 will undergo a biopsy
- Overdiagnosis of cancer occurs in 3 to 14 women leading to needless surgery, radiation, and chemotherapy
For every 1000 60-year-old women undergoing this annual test for ten years:
- 0.5 to 4.9 avoid dying from cancer
- 390-540 will have a false positive and of whom 50-70 will undergo a biopsy
- Overdiagnosis of cancer occurs in 6 to 20 women leading to needless surgery, radiation, and chemotherapy
False positive results can lead to great personal angst and fear, affecting your family, friends, and work life. Your life remains in limbo until further tests are done to rule out whether it is indeed a false result or does represent a finding of cancer. In the above example, changing the frequency to two years instead of annually would cut down on false positives and overdiagnosis.
Many women choose to participate in screening mammograms and no one can fault them. It is presented as a means of detecting early-stage breast cancer leading to greater chance of survival through earlier intervention. However, the details and statistics stated above do not usually enter into the decision-making conversation usually for reasons of time. Patients need to be fully informed of the benefits and harms be it screening or any other procedure or treatment regimen and thereafter will decide accordingly based on their individual risk tolerance. They can be given this information to take home and thunk about the issue before coming to a decision.
As my friend Dan Gardner discusses in his book Risk: The Science and Politics of Fear, we like certainty. We fear the unknown. We want to know what we can do to reduce our risk. We will cling to our perceptions of what can reduce our risk and ignore contrary evidence because it usurps our control and leaves us vulnerable. People cannot be faulted for this line of reasoning. It is how we evolved and how we assess and react to risk. In these situations, it is better to have something available to safeguard our health than nothing at all.
We think screening is of great value and for those for whom it works even more so. But it is important not to be sold on its virtues alone. We need to continuously evaluate the outcomes and adjust the criteria for testing towards specific groups based on verifiable scientific evidence. Rejecting the evidence because it overturns years of assumptions and general understanding does not improve health outcomes. Prostate cancer screening using the PSA test is one such area where we wirnessed the reaction of various organizations holding steadfast recommending PSA testing even when confronted with evidence stating that the test is fraught with false positives and leads to greater harm.
My purpose in posting this piece is not to advocate against breast cancer screening or screening in general. Indeed, I recommend my patients participate in the Ontario Breast Screening Program. This is especially true for women with the BRCA gene or family history of breast cancer. For the broader general female population without these risk factors or of average risk, the benefits and harms need to be explained and their decisions respected.
I used screening mammography in this discussion because it is one of the most studied and recommended screening tests in medicine. It exemplifies how we can easily ignore some of its limits as we do with other tests and procedures because we hope and believe it will help us. By presenting this information, I hope to generate a healthy discussion about screening tests in general amongst patients and their physicians. The book Testing Treatments goes into much more detail and is well worth the read.