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Rethinking routine screening recommendations
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Through appliance of science, we’ve got that ring of confidence/And I have no compass and I have no map. — U2
When logic and proportion/Have fallen sloppy dead/And the White Knight is talking backwards/And the Red Queen’s off with her head/Remember what the dormouse said/“Feed your head, feed your head.” — Grace Slick
As I am attempting to digest the latest screening recommendations that come at us as general pediatricians at an astonishing rate, I am not sure if U2 or Grace Slick better channels my feelings. Routine newborn hearing, HIV, critical congenital heart disease, obesity, hypertension, lipid, GC and Chlamydia, depression, expanded newborn, autism, and infant developmental are all currently endorsed screening programs. Even universal whole-genome screening is being debated.
What is our current screening paradigm? Although the concept of screening can be traced to the 19th century, significant research, debate and implementation of screening programs date to the middle of last century. Despite this relative lengthy history, it is not clear to me whether our current view of screening is a means to an end or is substituting for the end. Are our screening recommendations the sum of our prevention strategies?
Purpose of screenings
Screening recommendations remain controversial, often spilling into the public forum without a significant contextual background and placing those of us in primary care, at the bedside of families with questions, in an awkward and difficult spot.
This month in my practice, I experienced a range of emotions generated by expanded newborn screening. Notified of a positive genetic (one gene mutation) and biochemical (elevated trypsinogen) screen for cystic fibrosis (CF), I was told by the health department to bring the family back to my office for a discussion of the results, while not specifically mentioning the screening results. As I had just seen the 1-week-old infant that morning, it seemed to me that such an approach would be difficult to pull off. As I only had the boyfriend’s number, Mom’s phone was disconnected, I needed to inform the father of the results and arrange a follow-up evaluation at the CF center.
Shortly after that conversation, the mother called to explain that they had known of this possibility, as she had been identified as a carrier in a prenatal screen and the father had been subsequently screened without finding a known mutation. The nuances of known mutations, nature of CF disease and carrier status, likelihood of the infant testing “positive” on the newborn screen, or even thought toward informing the pediatrician of the prior evaluations appeared elusive to other providers, the family and our EMR.
In an attempt to outline the current context of screening, Russell Harris, MD, MPH, of the University of North Carolina, provided an excellent overview in a 2011 edition of Epidemiologic Reviews. He said with few exceptions, the contribution of screening to improving public health is small, yet it is an increasingly popular form of prevention. Indeed, the benefits of screening programs may be less than hoped and the harm greater. Disease and health are not typically distinctly different states, and the ambiguity of cutoffs in screening results are often arbitrary, lacking outcome testing in large, unselected populations. Risk prediction, overdiagnosis, predisease state, and the level of evidence (both certainty and magnitude considerations) necessary for recommendations by differing organizations with differing mandates and constituencies all contribute to the muddy waters of screening discussions in the office setting.
The need to engage with the public is very clear. The public’s interest in pursuing screening testing is already high. With direct-to-consumer advertizing of genome analysis and the proliferation of store-front laboratory blood testing sites that do not require physician orders, there will be even more. It is also apparent that both the ambiguity and likelihood of errors in testing results are known and not seemingly a deterrent. Unfortunately, we in primary care will likely then be engaged in lengthy discussions and even further testing as the stream of overdiagnosis becomes the Big Muddy.
Rethinking screenings
We should reconsider how we form our recommendations for screening. Harris helpfully recommends changing our thinking from “disease” or “predisease” to a larger conceptualization of a “predictor of poor health (PPH),” a probability continuum from weak to strong of the screened for data to predict a future adverse health event. Overdiagnosis then becomes the situation where we treat an individual with a weak PPH in the same way we treat one with a strong PPH. Such treatment of a patient, including making a diagnosis, in a situation where that person has little chance of having a poor health outcome from the condition, leads down the all-too-familiar path to the many layers of “harm.”
By overestimating the benefits and underestimating the harm of many of our current screening strategies, we have diverted resources, not only from research on basic biology and treatment modalities, but also from the development of alternative prevention strategies. We would be better served, both as a community and as pediatricians, if we refocused screening on smaller subpopulations with the highest potential benefit and lowest potential harm balance. Focusing on the hypertensive obese patient, for example, rather than on the “merely” obese; sexually active young adults rather than all adolescents, or perhaps more importantly those engaging in high-risk sexual activity rather than all sexually active youth.
Even more importantly, we should consider interventions that mandate changes in the salt content of foods, school lunch programs, exercise opportunities, sex education, limits on snack food advertising, and the fast-food industry as better models to advance the public health.
References:
- Harris R. Epidemiol Rev. 2011;33:1-6.
William T. Gerson, MD, is Clinical Professor of Pediatrics at the University of Vermont College of Medicine and a member of the Infectious Diseases in Children Editorial Board. Disclosure: Dr. Gerson reports no relevant financial disclosures.