Overdiagnosis and overtesting
Are we dooming ourselves with too much COVID19 testing?
I am pleased to feature a Guest Post by Dr. Sebastián González-Dambrauskas. He is a pediatric ICU pediatrician based in Montevideo, Uruguay. He is a scholar and deep thinker. You can follow him @sgdambrauskas
Dr. Sebastián González
Overdiagnosis needlessly turns healthy people into patients through the identification of problems that are not going to cause harm or by medicalizing ordinary life experiences through expanded definitions of diseases. Its two major causes are overdetection and overdefinition of disease and the final consequence of both is the same: a diagnosis which leads to more harm than benefit (Brodersen J et al 2018[Ss1] ). When you detect an anomaly or condition which was not destined to cause harm, you enter into the overdiagnosis zone. Transforming healthy people into patients leads to overmedicalization, overtreatment, diagnosis creep and disease mongering, producing net harm, both at the individual and population level ([Ss2] ).
We are currently facing a global surge of covid19 cases. Skyrocketing graphics and scary exponential numbers fill the media coverage. At the same time, Mortality related to COVID19 is at its lowest since the pandemic began, while population immunity is in its highest. How can we explain the explosion in numbers and the disconnect between numbers and burden of severe disease? How did we get to this scenario? One of the answers may be: overtesting.
A Pubmed search (overdiagnosis AND covid19) found only 25 results among 203.000 covid19 indexed papers as of 30th December 2021. None of those 25 specifically addressed overdiagnosis as a public health issue during the current pandemic ([Ss3] ). While in the early phase of the pandemic (without immunity) testing might be of net benefit ([Ss4] ), once immunity is gained (through vaccination and/or prior exposure) the equation between benefits/harms changes, and diagnosing the present of viral particles in the noses of millions become problematic.
Testing vaccinated and asymptomatic individuals when the clinical significance of a positive test (both in terms of transmission and disease development) is uncertain is a good example. We know, and the CDC acknowledges, that PCR tests can remain positive after 12 weeks (ref[Ss5] ). Testing asymptomatic people is tricky and major harms become obscured. For example, the economic and social costs related to isolating millions of healthy people (most of whom would never get severely sick) in this phase of the pandemic are huge.
Consider the UK, which is now planning for the absence of up to 25% of workers from their workplaces due to covid19 cases (Ss6] ). Overtesting could per se, overwhelm the health care system (particularly during covid19 surges) if healthcare workers (HCW) are isolated without need, reducing the HCW force, leading to worsening outcomes and increasing mortality due to hospitals and ICUs constraints ([Ss7] ). People will die when the people who should be taking care of them are needlessly isolated at home and the quality of care lowers.
Overtesting has ballooned to an extent in which testing capacity becomes overwhelmed ([Ss8] ). Paradoxically, the healthcare system can be jeopardized by the increasing demand of testing by those seeking covid19 tests ([Ss9] ). Given the unprecedented scale of testing during the current pandemic, this should be of no surprise. The frenetic and myopic focus on sars-cov-2 has led us to forget that asymptomatic carriers of respiratory viruses are very common across age groups ([Ss10] ). Our noses are used to carrying such viruses, and so much so, we often do not even notice their presence. The same likely occurs with sars-cov-2. The difference is that we now have made widely available the technology (which used to be restricted to the hospital environment) to the general public, making the perfect laboratory for global viral screening and overdiagnosis. Unfortunately, the general response to overtesting has been increasing testing capacity in a never-ending circle, instead of focusing on the roots of the problem.
Testing needs a rethink at this stage of the pandemic since it has become one of the major obstacles to the return to our normal lives and leads to multiple socio-economic harms (ref[Ss11] ). Testing will cost billions to our societies (both in direct and indirect costs) and we should be making the greatest efforts to recalibrating their precise indications. Eliminating the virus and find it in every nose of the world is an unrealistic goal full of surprises and collateral damages. Testing has steadily turned into a glooming market, departing from a real public health tool and is now a major threat.
Too much medicine has been recognized as one of the major healthcare threats during the last 20 years (Moynihan R et al, 2002 [Ss12] ). Overtesting, a face of overdiagnosis, is still preventable. We need focused and fewer tests, not more testing, to overcome the pandemic of overdiagnosis we have created. The virus will become soon become endemic. Its’ harms matter, not its’ nucleotide sequence.