For the first time, the American Academy of Pediatrics (AAP) released clear-cut criteria for diagnosing children when they are not growing as quickly as their peers. 

For generations, kids who fell below the fifth percentile for height and weight were diagnosed with ‘failure to thrive.’ The updated guideline also gave the diagnosis a new name: faltering weight. 

“The term ‘failure to thrive’ is pejorative, it’s blaming the parents,” said Hans Kersten, MD, pediatrician at St Christopher’s Hospital for Children in Philadelphia, who co-authored the guideline and is chair of the AAP’s Guideline Panel on Faltering Weight. 

The shift to ‘faltering weight’ brings US guidance in line with international definitions for the condition. In Europe, clinicians use the term ‘faltering growth,’ after the National Institute for Health and Care Excellence –– an independent organization that provides medical guidance in the UK –– first used the term in official guidelines in 2017. 

Z-Scores Provide a More Nuanced Diagnosis

Previously, US clinicians used one of as many as eight definitions to diagnose the condition, Kresten said. For instance, the Gomez criteria is based on median weight by age, whereas conditional weight gain is calculated based on a child’s BMI and how slowly they gain weight.

“There was no consensus on which definitions we should use. Everyone was left to use whatever criteria they felt was right,” Kresten said.

The new AAP guideline state pediatricians should continue to use growth charts from the World Health Organization or CDC for initial screening. If a child falls below the fifth percentile on the chart, clinicians should use an equation that measures how many standard deviations a child is below the average size of their peers, also known as a z-score. The score is aimed at capturing more nuance about a child’s size and condition.

“When you have two different kids, one might be just below the fifth percentile, and another could be far below that fifth percentile, but they have the same diagnosis,” said Senthilkumar Sankararaman, MD, co-director of the Pediatric Advanced Nutrition Program at Cleveland Clinic Children’s in Cleveland, who was not involved with the AAP guidelines.

Z-scores should also be used to track progress. If a child’s z-score improves, the patient’s status is improving despite still carrying the faltering weight diagnosis.

“It allows for a lot more nuance between patients,” Sankararamen said.

Z-scores can also help diagnose malnutrition, Kersten said. A z-score less than -3 indicates severe malnutrition, while -2 and -1 are cutoffs for moderate and mild malnutrition, respectively.

Kersten said the AAP is developing tools to help pediatricians transition to using z-scores in their practice. Z-scores can be calculated using a mathematical equation, and some healthcare facilities may offer tools that automatically do the calculation based on age, sex, weight, and height.

“We recognize that this is a new ask for pediatricians and the AAP is developing tools and modules that would make it easier for physicians who aren’t familiar with z-scores or who don’t have access to z-scores,” Kersten said. 

For Subspecialists

For the first time, the AAP partnered with the North American Society for Pediatric Gastroenterology, Hepatology, and Nutrition to pen guidelines for next steps if a child does not make progress. If initial interventions from a pediatrician do not improve a child’s weight, referrals should be made to a gastroenterologist to investigate the root cause.

The committee reviewed six studies analyzing the benefit of endoscopy. Based on these findings, endoscopy should not be used during an initial workup for faltering weight, the guidelines state. The procedure should only be ordered if a child does not improve, or if a pediatrician suspects a condition that can only be diagnosed with an endoscopy, such as eosinophilic esophagitis.

The AAP also recommends against universally using diagnostic tests –– such as complete blood count, urinalysis, and iron studies –– as part of their initial workup. If a child continues to struggle to gain weight even on a higher calorie diet, then a pediatrician may consider running such diagnostic labs to test for underlying conditions, the guidelines state.

Various study authors reported having relevant financial disclosures related to Jannsen Bio Tech, Baxter Healthcare, Boehringer Ingelheim, among others.