Growth patterns in early life affect lung health of older children, adults

Lung function better in CF children above 50th percentile for size by age 5

Lindsey Shapiro, PhD avatar

by Lindsey Shapiro, PhD |

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A better growth trajectory over the first years of life was associated with more favorable lung function at age 6 for children with cystic fibrosis (CF) in the U.S., a study reported.

Children who were consistently above the 50th percentile in size through age 5 — as recommended by the Cystic Fibrosis Foundation (CFF) — had the best lung function, whereas those consistently below it had the worst.

An early CF diagnosis also associated with better growth, while female sex linked with a poorer trajectory.

“Optimizing nutritional status in childhood remains a crucial aspect of early CF management,” the researchers wrote, adding that understanding how growth relates to lung function can help care teams and families in making decisions that “ultimately improve long-term health outcomes.”

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Study in 6,809 young children taking part in CFF Patient Registry

The study, “Early life growth trajectories in cystic fibrosis are associated with lung function at age six,” was published in the Journal of Cystic Fibrosis.

Poor growth is an early manifestation of CF, arising from a combination of limited nutrient intake, poor absorption of fats and proteins in food, and increased metabolic demands.

Stunted growth and nutritional deficiencies can continue into adolescence and adulthood, and studies link low weight in early childhood with worse lung function. The CFF recommends that young patients achieve a weight-for-body length at or above the 50th percentile by age 2, and then, through age 20, maintain a body mass index (BMI, a measure of body fat) at or above the 50th percentile.

While earlier diagnoses and better treatments, like CFTR modulators, have helped, “early growth challenges remain common and stressful for caregivers,” according to the research team, led by those at Johns Hopkins. The scientists noted that less than 2% of the children in their study, which ended in 2017, were on modulator therapy.

A better understanding of early life growth trajectories could help in clarifying why some children fail to thrive, and which children may benefit from specialized interventions.

Researchers used early growth and later lung function data covering 6,809 children with CF born between January 2000 and December 2011 and part of the CFF Patient Registry. All were diagnosed before age 2, most were white (90.6%), with 10.5% identifying as Hispanic, and females comprised 50.4% of this group.

For children under age 2, growth was measured as the weight-to-body length ratio, whereas children 2 and older were assessed using BMI.

Six distinct growth trajectories, from birth through age 5, were identified for the children. Three covered the roughly half of young patients (51.6%) who started with a size above the 50th percentile for their age, and either remained high (19.1%), gradually declined (18.9%), or rapidly declined (13.7%) over time.

The other three were in children starting off below the 50th percentile, and categorized as always low growth (14.8%), rapidly rising growth (15.7%), or gradually rising growth (17.9%).

By age 5, two groups had an average BMI below the 50th percentile — rapid decliners and always low growth — while BMI for children in the other four groups put them above the 50th percentile.

Highest percent predicted FEV1 in children in most favorable growth group

Lung function was assessed at age 6 using the forced expiratory volume in one second (FEV1) measure. Children in the always high growth trajectory — the most favorable growth category — showed the highest percent predicted FEV1 (ppFEV1) for their age, with a mean of 98.9.

This group was followed by those in the rapid risers (mean ppFEV1 of 96.6), gradual decliners (mean of 96.1), gradual risers (mean of 94.1), and rapid decliners (mean of 93) categories. The “always low” group — the least favorable growth category — showed the poorest lung function at age 6, with a ppFEV1 of 88.9.

Girls were less likely to be in the higher growth trajectory groups at age 6, as were children with pancreatic insufficiency, the study noted.

“These findings are consistent with sex differences seen in older children and adolescents, including differences in BMI, rates of pulmonary exacerbations and survival, indicating a need for increased attention to early growth among young females,” the researchers wrote.

Other contributing factors were diagnoses made through newborn screening and at younger ages, each of which linked to better growth, as did being Hispanic.

Fewer children in the always high group (6.9%) required a feeding tube compared with those in the always low group (32%).

While few study children were on CFTR modulator therapy, its use was most frequent among children with continuously high growth. The researchers favored future studies into modulator use and growth, “particularly given changes in [therapy] eligibility based on age and genotype [disease-causing mutations].”

Overall, their findings provide “support for the nutritional benchmarks set forth in the CFF guidelines and highlight the importance of optimizing early life nutritional status in children with CF to help improve health outcomes,” the researchers wrote.

While they also “suggest who might be at risk,” the factors identified alone cannot predict growth trajectories.

Other psychosocial factors, like caregiver beliefs about nutrition and a child’s temperament, could play important roles and also should be the topic of future study, the team added.

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