Gut Check is a periodic look at health claims made by studies, newsmakers, or conventional wisdom. We ask: Should you believe this?

The Claim:

Screening young children for developmental delays, though they seem fine to their parents and pediatrician, does not reduce the chances that they will have learning difficulties and other problems later, according to a study last week in the Canadian Medical Association Journal.

The Background:

This is not about parents and pediatricians watching for signs of delays in speech, language, motor, and other skills by observing 1-to-4-year olds in ordinary interactions or at doctor visits. That, especially doctors’ expert judgment, is worthwhile, experts agree.

The question is, instead, about the value of standardized questionnaires that are filled out by parents and meant to uncover unnoticed developmental delays.

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The screening tests are big business, bolstered by scary messages about missing signs of problems. One company, for instance, warns that “developmental delays in children can be subtle and can occur in children who appear to be developing typically,” adding that “busy pediatricians” fail to flag such children. A four-page guide on using the checklist costs $24.95, and the questionnaire costs $225.

Logically, it seems such screening should be beneficial. Why not uncover overlooked cases? And how can intensive interventions not help put little kids flagged by such screening on course for normal development?

Surprisingly, scientific support for both propositions is shaky.

The flimsiness of research on the benefits of screening is a longstanding problem. Last year, the US Preventive Services Task Force, a panel of outside physicians and other experts who make health care recommendations to the government, reported that there is “no evidence to answer the overarching question of whether screening for speech and language delay or disorders improves speech and language outcomes.” It found insufficient evidence to recommend for or against screening.

First Take:

In the latest analysis of screening every child for developmental delays, the Canadian Task Force on Preventive Health Care recommended against screening preschoolers who seem normal to their parents and pediatricians.

The trouble begins, it explained in the journal, with the screening checklists that parents fill out (Is your toddler speaking in sentences? Can he pick up small objects?). These tools identify as developmentally delayed many children who, upon examination by a developmental expert or pediatrician, turn out not to be. As many as 55 percent of those labeled as delayed are not, a 2015 analysis found.

Those “false positives” cause unwarranted parental anxiety and burden specialists who should be helping truly delayed children, said pediatrician Dr. Patricia Parkin of Toronto’s Hospital for Sick Children, a member of the task force.

The screening tools also fail to catch many children who are developmentally delayed. And “there is no evidence that commonly used screening tools would consistently identify otherwise unrecognized cases,” the Canadian panel wrote.

The other problem is that whatever value the screening tools have depends on the follow-up. It doesn’t help a child to be identified as developmentally delayed unless he or she then receives interventions that avert or diminish learning difficulties and other common consequences of developmental delays.

Unfortunately, there have been only two rigorous scientific tests of whether screening seemingly normal kids improved how well they did in school and other important outcomes. One study, in the United States, found that screening did identify kids with otherwise-unrecognized developmental delays, made it more likely that they would be referred to a specialist, and also made it more likely that they would receive federally funded interventions. But it did not answer the key question: Did all this improve outcomes? “Just because a child is referred [to a learning specialist] earlier doesn’t mean there will be meaningful improvements” compared to children who are not referred, Parkin said.

The other study, in the Netherlands, showed that there was no significant difference in how well kids did in school between those who were formally screened and those who weren’t.

Nor is there evidence that offering interventions to children identified by screening, but not by pediatricians and parents, improves their outcomes. In all likelihood, Parkin said, such children make up their subtle delays on their own.

Second Take:

The American Academy of Pediatrics recommends that children undergo developmental screening — the checklists and questionnaires — at ages 18 months and 30 months, in addition to pediatricians observing them for delays at nearly every visit.

Dr. Joseph Hagan of the University of Vermont, a pediatrician who helped develop those recommendations, said absence of evidence for the benefits of screening is not evidence of absence. Instead, he said, the lack of evidence “usually means a lack of studies,” which are difficult to conduct, so “we’re not put off” by claims of insufficient evidence.

“We reached the conclusion that [screening] is of value,” he said. “There were no studies [demonstrating benefit], but we felt we should move forward. There is a great belief that early intervention makes a difference.”

The Takeaway:

There is no solid evidence that developmental screening of every child helps those who are identified as delayed.

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