Study: Most CF Infants Had Healthy Stools in First Year

Steve Bryson, PhD avatar

by Steve Bryson, PhD |

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Stool consistency and frequency were healthy for the majority of infants with cystic fibrosis (CF) in the first year of life, according to an analysis of data from the BONUS study.

Stool consistency and frequency were not associated with pain, while infants exclusively fed with formula or who received acid suppression medication had a decreased risk for constipation.

“[These] data can aid parents and providers in understanding the impact of feeding choices and prescribed medications on the stool pattern in infants with CF during the first year of life,” the researchers wrote.

The study, “Association between stool consistency and clinical variables among infants with cystic fibrosis: Findings from the BONUS study,” was published in the Journal of Cystic Fibrosis.

The buildup of abnormally thick and sticky mucus in the lungs, liver, pancreas, and intestines is a hallmark of CF. Gastrointestinal (GI) symptoms in infants with CF are common and frequently occur before the onset of lung symptoms.

Concerns related to stool consistency are common among parents with CF infants. Disease management guidelines for infants recommend visiting a medical provider when problems related to stool and/or abdominal pain arise. Despite these findings, stool patterns in CF infants have not been described in the literature.

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The Baby Observational and Nutrition Study (BONUS) (NCT01424696) was a multicenter study of 231 infants with CF diagnosed by newborn genetic screening, which examined weight gain and growth in the first year of life. The study also explored clinical characteristics, including nutrition, medications, and inflammation.

In this study, researchers at various children’s medical centers across the U.S. used BONUS data to describe the frequency and characteristics of stool in these children. The impact of feeding and common medications on stool consistency, as well as the relationship between stool consistency and abdominal pain, also was investigated.

Among the participants, 57.1% carried the F508del mutation in both CFTR gene copies (one from each parent), a common genetic defect that causes CF.

In the first year, acid suppression medication was prescribed to 153 (66.2%) infants, and 176 (76.2%) received antibiotics. Admission to the hospital for any cause was reported for 65 (28%) children, of which 21 (9%) were admitted for GI problems.

The proportion of infants described as being most comfortable, or having no reported abdominal pain, increased significantly from 37.1% at 3 months old to 50.5% at 6 months and 66.3% by 1 year.

The occurrence of constipation was stable throughout the first year of life, ranging from 10.8% to 12.9%, while watery stool significantly decreased from 21.3% at 3 months to 5.8% at one year. The mean number of stools at 6 months (2.4) and 1 year (2.5) were significantly lower than at 3 months (2.8), with no difference between months 6 and 12.

As expected, the feeding type changed throughout the first year. After adjusting for follow-up time, exclusively breastfed babies had a 2.64-times increased risk for constipation compared to those given a combination of breastmilk and formula. In contrast, infants who received formula had only a significantly decreased risk of constipation.

“The association between breast feeding and constipation may be driven by a reduced frequency of stools often observed among breast-fed infants, which may be perceived to be constipation and is defined as such in this analysis,” the team wrote.

“Given the known benefits of human milk feeding and the relatively low prevalence of constipation throughout infancy, this should not influence the decision to provide breast milk or not and the authors continue to advocate for breast milk in all infants with CF,” they added.

Acid suppression treatment also was associated with a decreased risk of constipation. In comparison, the use of stool softeners was associated with a 2.51-times increased risk of constipation, which was “of no surprise,” the researchers noted.

Constipation was not linked to pain, antibiotics, calprotectin levels (a biomarker for intestinal inflammation) and the dose of pancreatic enzyme replacement therapy (PERT) given for pancreas deficiency due to mucus buildup. None of the study variables were associated with watery stools.

These data “suggests that common medications such as PERT, acid suppression and antibiotics have less impact on stool consistency than previously perceived,” the researchers wrote.

“Stool consistency is healthy in the majority of infants with CF and is not associated with pain,” the authors concluded. “Infants who were exclusively formula-fed or received acid suppression medications had a decreased risk of constipation.”