Screening for presymptomatic disease provides the potential for early intervention and improved outcomes. However, although this practice has potential benefits, it also has potential harms that must be considered. The U.S. Preventive Services Task Force (USPSTF) is a nonfederal panel of experts convened by the Agency for Health Research and Policy to systematically review the evidence for preventive services, including disease screening, and to create evidence-based recommendations for primary care practice in the United States. As rheumatologists contemplate the potential of screening for preclinical disease, understanding the process used by the USPSTF can help guide research efforts supporting such screening.
Key points
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Screening for preclinical rheumatic disease may improve health by enabling treatment to start before clinical symptoms occur.
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Potential health harms associated with screening programs, such as the harms associated with false-positive tests and overdiagnosis, must be weighed against health benefits.
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The U.S. Preventive Services Task Force (USPSTF) uses an explicit process to create evidence-based screening recommendations that assess net benefit, or benefits minus harms.
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Screening tests recommended by the USPSTF are provided with first dollar coverage under the Affordable Care Act.
Introduction
In the clinical prevention world, screening for the early detection of disease is categorized as secondary prevention, involving interventions that are implemented after the asymptomatic onset of biologic disease, but before the progression to symptomatic disease that would be diagnosed through the usual health care approach. Conceptually, intervening early leads to better health outcomes than does waiting until the disease manifests clinically. Good examples of effective screening modalities exist in the chronic disease arena: screening for cervical cancer with cytology can almost eliminate deaths from this cancer, and screening for and treating hypertension significantly reduces the occurrence of atherosclerotic disease in the coronary and cerebral arteries in nearly all adult age groups. A broader definition of screening, brought to the forefront of medicine by the current interest in genetic testing, involves screening for the risk of disease and intervening even before the biologic onset of a condition. This new technology will continue to bring new challenges for decision making in screening programs.
Screening for asymptomatic or preclinical rheumatic conditions has the potential for providing improved disease outcomes, with the early treatment of disease using safe and effective therapeutics started before symptomatic tissue damage. However, even though screening is conceptually appealing, as it is in other conditions, it has downsides in terms of the potential for harm, which is associated with almost all medical interventions. Screening benefits must be weighed against harms when deciding to offer screening.
The benefits of screening are straightforward: early intervention leads to earlier treatment and better health outcomes. On the other hand, 4 or 5 categories of potential harms exist. A test can be falsely negative, creating false reassurance and the potential to delay the diagnosis of a treatable condition when patients ignore symptoms. The test may be falsely positive, arguably the most important negative outcome, leading to unnecessary and potentially harmful diagnostic tests, treatment, and labeling. The test could overdiagnose disease that does not require treatment. In this scenario, the test result is a true-positive, but detects disease that would not progress, meaning that any treatment is unnecessary. Overdiagnosis is a critical harm associated with screening for prostate cancer, in which most cancers are indolent and would never impact the patient’s health, and screening for breast cancer, in which most ductal carcinoma in situ does not benefit from treatment. Finally, the test can be correct, but early detection may have no real benefit, and therefore screening consumes resources, increasing the cost of medical care without health benefit. In addition, harms may be associated with the test itself, such as additional radiation exposure with x-ray screening, which could, over a lifetime of screening, increase the risk of disease, or, in the case of a somewhat invasive test such as colonoscopy, the test may carry the risk of adverse outcomes, including hemorrhage and perforation.
The evidence bar tends to be set high for screening, more so than for other medical interventions, because the population targeted is asymptomatic. If clinicians are going to medically intervene with people who are otherwise well and clinically manifesting no illness, they should only do so based on strong evidence showing that the benefits well outweigh the harms.
Introduction
In the clinical prevention world, screening for the early detection of disease is categorized as secondary prevention, involving interventions that are implemented after the asymptomatic onset of biologic disease, but before the progression to symptomatic disease that would be diagnosed through the usual health care approach. Conceptually, intervening early leads to better health outcomes than does waiting until the disease manifests clinically. Good examples of effective screening modalities exist in the chronic disease arena: screening for cervical cancer with cytology can almost eliminate deaths from this cancer, and screening for and treating hypertension significantly reduces the occurrence of atherosclerotic disease in the coronary and cerebral arteries in nearly all adult age groups. A broader definition of screening, brought to the forefront of medicine by the current interest in genetic testing, involves screening for the risk of disease and intervening even before the biologic onset of a condition. This new technology will continue to bring new challenges for decision making in screening programs.
Screening for asymptomatic or preclinical rheumatic conditions has the potential for providing improved disease outcomes, with the early treatment of disease using safe and effective therapeutics started before symptomatic tissue damage. However, even though screening is conceptually appealing, as it is in other conditions, it has downsides in terms of the potential for harm, which is associated with almost all medical interventions. Screening benefits must be weighed against harms when deciding to offer screening.
The benefits of screening are straightforward: early intervention leads to earlier treatment and better health outcomes. On the other hand, 4 or 5 categories of potential harms exist. A test can be falsely negative, creating false reassurance and the potential to delay the diagnosis of a treatable condition when patients ignore symptoms. The test may be falsely positive, arguably the most important negative outcome, leading to unnecessary and potentially harmful diagnostic tests, treatment, and labeling. The test could overdiagnose disease that does not require treatment. In this scenario, the test result is a true-positive, but detects disease that would not progress, meaning that any treatment is unnecessary. Overdiagnosis is a critical harm associated with screening for prostate cancer, in which most cancers are indolent and would never impact the patient’s health, and screening for breast cancer, in which most ductal carcinoma in situ does not benefit from treatment. Finally, the test can be correct, but early detection may have no real benefit, and therefore screening consumes resources, increasing the cost of medical care without health benefit. In addition, harms may be associated with the test itself, such as additional radiation exposure with x-ray screening, which could, over a lifetime of screening, increase the risk of disease, or, in the case of a somewhat invasive test such as colonoscopy, the test may carry the risk of adverse outcomes, including hemorrhage and perforation.
The evidence bar tends to be set high for screening, more so than for other medical interventions, because the population targeted is asymptomatic. If clinicians are going to medically intervene with people who are otherwise well and clinically manifesting no illness, they should only do so based on strong evidence showing that the benefits well outweigh the harms.
Framework for disease screening
In creating a framework for deciding whether to implement a disease screening program, Wilson and Jungner created a list of critical criteria to assess. Paraphrasing this sentinel article, these criteria include the following queries:
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Is the disease an important health problem (in terms of severity and incidence)?
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Does the disease have a recognizable presymptomatic stage that lasts long enough to allow for screening, diagnosis, and treatment?
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Are acceptable and reliable screening tests available for the presymptomatic stage?
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Does treatment of the disease during the presymptomatic stage result in improved outcomes?
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Do sufficient resources exist for diagnosing and treating the population with positive screening results?
A group of evidence-based medicine researchers reframed these criteria for today’s evidence-based approach in 2011, stating that the fundamental question to answer when determining whether to screen should be whether the program, if implemented under present conditions, would result in sufficient net benefit (benefits minus harms) to justify starting (or continuing) the program given the level of resources required. This determination should include an evidence-based consideration of several factors, including the probability of an adverse health outcome without screening, the degree to which screening identifies all those who would experience the adverse health outcome, and the magnitude of incremental health benefit conferred by earlier treatment initiated as a result of screening. Also important in the assessment of a screening test are the frequency of false-positive tests; the experiences of people with false-positive results, including the frequency and severity of workup and treatment; and the frequency and severity of outcomes associated with overdiagnosis.
Process of the united states preventive services task
These considerations guide the process of the U.S. Preventive Services Task Force (USPSTF), an independent panel of nationally recognized, nonfederal experts experienced in primary care, disease prevention, evidence-based medicine, and research methods. The USPSTF, which is hosted by the Agency for Health Research and Quality, was created in 1985 and charged by Congress to review the scientific evidence for clinical preventive services and develop evidence-based recommendations for the health care community. Under section 2713(a)(1) of the Affordable Care Act, the recommendations from the USPSTF have taken on greater importance; recommendations that are graded A or B (described in detail later) will involve services covered by all insurers, with no additional out-of-pocket costs to the patient (ie, first dollar coverage).
The USPSTF uses an explicit process that can be categorized into specific steps:
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Define the question about the provision of a preventive service within an analytical framework and using a set of key questions.
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Define, retrieve, and review the relevant evidence; judge the quality of individual studies; and summarize the evidence for each key question.
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Synthesize and judge the strength or adequacy of the body of evidence for each, and across all, key questions.
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Determine the magnitude of net benefit (the balance of benefits and harms).
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Judge the certainty of net benefit.
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Link magnitude and certainty of net benefit to a recommendation statement/letter grade.
The steps are implemented in 2 integrated activities, one being a systematic evidence review (SER) that addresses the literature search, study quality rating, and summary of the evidence on the magnitude of benefits and harms. The other process, the recommendation process, takes the SER results, assesses the strength of evidence, and determines the magnitude and certainly of net benefit and the corresponding letter grade/recommendation statement.
Step 1: Define the Analytical Framework and Key Questions
The analytical framework defines the clinical scenario for the topic—who are you screening, how, for what condition, in what setting, and for what purpose—and creates a set of key questions that guide the SER and decision making. A generic analytical framework for evaluating a screening test is presented in Fig. 1 , in which the numbers refer to the list of key questions:
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Does direct evidence show that providing the service improves health outcomes if implemented in a general primary care population? Outside of treatment scenarios, sufficient direct evidence is rarely available. If insufficient evidence is available to answer this question, the remaining framework allows the creation of a chain of evidence to support a recommendation.
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Can a population at risk and/or at increased risk be identified? Higher-risk populations have a higher rate of disease, and this translates to better screening test performance (specifically, fewer false-positives).
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Does screening reliably lead to preclinical/earlier detection? This question deals with the screening test utilities of sensitivity, specificity, and predictive values of positive and negative tests.
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Does treatment of screening-detected disease lead to improvement in important health outcomes, including mortality or morbidity? This critical question was often not satisfactorily addressed before the widespread adoption of some screening tests, as evident with prostate-specific antigen testing for prostate cancer.
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Are harms associated with specific parts of the screening process, including risk identification, screening itself, confirmatory diagnosis for people with positive tests, and treatment?
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