With the rapid emergence of genomic tests, healthcare providers, patients and policy makers need to know how useful they are and whether the benefits of their use outweigh potential harms to patients, families, and the population.
CDC’s Office of Public Health Genomics now offers a list of health-related genomic tests and applications, stratified into three tiers according to the availability of scientific evidence and evidence-based recommendations. The list is intended to promote information exchange and dialogue among researchers, providers, policy makers, and the public. It will be updated on an ongoing basis and with references and links to key publications and online materials.
Tier 1 genomic applications have been recommended for use by groups such as the U.S. Preventive Services Task Force or EGAPP, based on a systematic review of the evidence for their validity and utility in specific clinical scenarios. We encourage the use of tier 1 applications in practice because they can lead to improved health outcomes. To date, very few genomic applications have risen to tier 1.
Tier 2 genomic applications have demonstrated analytic and clinical validity. Providers and patients may find them useful for informed decision making but the evidence for their utility has either not been reviewed or has been found insufficient. With a few exceptions, we have classified nearly all tests for single gene disorders—as well as the collection of family history in primary care—as tier 2. This classification reflects a lack of sufficient data (especially for rare conditions) or the lack of evidence-based recommendations. Further development and review of evidence will help close the gap.
Tier 3 genomic applications have not yet demonstrated adequate analytic validity, clinical validity, or clinical utility. This tier also includes applications that evidence-based panels have recommended against after evaluating the balance of related benefits and harms. Such applications are not ready for use in practice but may be considered for use in clinical and population research.
Our goal is to encourage conversation on the appropriate use of genomic applications in practice and to promote the translational research needed to fill evidence gaps. The tables also highlight some mature genomic applications in tier 1 that if implemented could save thousands of lives and reduce morbidity among affected people and their families. Evaluating the population-level balance of benefits and harms will require further research.
A true partnership between clinical medicine and public health is needed to implement evidence-based genomic applications using a combination of education, policy changes, population surveillance and programs.
We invite comments and suggestions from our readers about our classification scheme, specific genetic tests and applications, and sources of evidence.