Newborn Screening for Duchenne Muscular Dystrophy Workgroup: Lay Report
Newborn screening is a public health program aimed at early identification of babies with conditions that will benefit from early diagnosis and treatment. Historically, these are conditions that cause disability or death if they are not treated within days of birth. Newborn screening has been performed in the United States since the early 1960s. Newborn screening tests are performed on blood from a small prick in the baby’s heel. A few drops of blood are collected on a special kind of paper, and then the “blood spot” is dried and sent to a laboratory for analysis. In the United States, several factors are taken into account when deciding if a particular screening test should be routinely performed on all newborn babies, and each state determines which disorders are included in its newborn screening program.
It is important to understand the difference between a screening test and a diagnostic test. Screening tests will identify people who are more likely to have a certain condition than are other people, but screening tests are not definitive. That is, not all people who have a positive result on a screening test will actually have the condition. People who screen positive are referred for a follow-up diagnostic test. A diagnostic test will tell with greater certainty whether these people have the condition. If a person is positive on the screening test, but is negative on the diagnostic test, the person does not have the condition and the screening result is said to be a “false positive”. Likewise, there could be some people with the condition who are not detected by the screening test. The screening test results on these people are “false negatives”.
So if screening tests aren’t perfect, why aren’t the diagnostic tests used on everyone? Generally, diagnostic tests are too expensive to offer to everyone. Screening tests are much less expensive, and public health officials consider how good the screening test is when deciding whether or not to offer the screening test. Ideally, a test will have no false negatives, and few or no false positives. False-negative results could cause a delay in diagnosis and treatment and can, therefore, lead to harm.
False positive results increase the number of diagnostic tests that are performed and, therefore, increase the cost of the screening program. In addition, false-positive results could cause undue anxiety in parents who might continue to worry that the diagnostic test was wrong and worry that their child really does have the condition. Some studies have found that the stress and anxiety from a false-positive screening result can last for years.
In addition to cost and the number of false-positive and false-negative screening results, there are several other factors that are considered before making a screening test available to the general population. Different countries and even different states within the United States use different criteria for deciding which screening tests to perform on newborn babies. Other important factors include the severity of the condition if the baby is not treated right away, the availability of diagnostic tests, and the availability of treatments.
In the United States, newborn screening for a particular condition is generally performed only if there is evidence that early diagnosis and early treatment will result in an improved medical outcome for the child. There are several arguments for this criterion. One argument is that newborn screening is potentially harmful (for example, it might cause increased stress and anxiety for parents if the screening test result is a false positive) and that a proven medical benefit for the children who are diagnosed with the condition is necessary to outweigh potential harms.
Another argument is that decisions regarding a baby’s medical testing and care are the right and responsibility of the parents, and that routine newborn screening takes this decision out of the hands of the parents. Therefore, universal newborn screening is justified only if harm to the child will occur if the condition is not diagnosed and treated in a timely manner. To address this issue, some states have two different sets of newborn screening tests that are offered to new parents: mandatory and optional. In most states, mandatory tests are routinely performed on all newborn babies unless the parents refuse the tests in writing. In a few states, parents are not allowed to “opt out” of the test (that is, decline to have the test done) and all babies are screened. Some states offer newborn screening as an option for an additional set of conditions. Generally, tests are offered on an optional basis if there is reason to believe that early diagnosis and treatment will result in a better medical outcome, but more studies are needed to confirm the medical benefits. Optional newborn screening tests generally require signed, informed consent by a parent. Informed consent means that the parents gave their permission, or consent, for their baby to be screened after they were informed of the risks, benefits, and limitations of the screening test.
Centers for Disease Control and Prevention content is free and public domain.
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