Children’s Wheezing Should Not Be Mistaken for Asthma
Wheezing — noisy breathing with a whistling sound — occurs in nearly three of every four preschool-aged children with cystic fibrosis (CF), and its presence at age 6 is linked to worse lung function, a French study has found.
Researchers also observed that the majority of older children and adolescents with CF had a positive bronchodilator response (BDR), meaning that blockage of the airways could be reversed with the use of bronchodilators, which are medications that ease breathing by relaxing muscles in the lungs and widening the airways.
“Most children with CF behave like non-specific asthmatic patients,” researchers wrote, adding that this raises questions about the most adequate treatment for these patients.
The study, “Prevalence and determinants of wheezing and bronchodilatation in children with cystic fibrosis: a retrospective cohort study,” was published in the journal Frontiers in Pediatrics.
Many patients with CF wheeze as they breathe. For this reason, they are sometimes dubbed as having “CF asthma.” However, it can be difficult to determine who wheezes as a result of breathing problems and who actually has asthma.
“Understanding the determinants of such wheezing may avoid unnecessary treatments and open newer treatment avenues,” the researchers wrote.
Now, a team of scientists set out to determine how common wheezing and BDR are among children and adolescents followed at a CF clinic at the Bordeaux University Hospital in France.
In the first part of the study, the researchers focused on 125 children (69 girls and 56 boys) who were younger than 6 when they attended the clinic from February to June 2016.
Of the 125 children, 89 (71.2%) had experienced at least one episode of wheezing from birth up to the time when they were 6. Of the 95 children who reached 6 years of age, 73 (76.8%) had experienced at least one episode and 46 (48.4%) had experienced at least three episodes of wheezing.
Among this group of 73 children, there were 25 (26.3%) with transient early wheezing, meaning they experienced wheezing from birth to age 3, but not at age 6. There were 12 (12.6%) who experienced wheezing only at age 6 (late-onset wheezing) and 36 (37.9%) who experienced wheezing both at age 0–3 and later at age 6 (persistent wheezing).
A significantly greater proportion of children who had never wheezed (72.7%) had two copies of the CF-causing F508del mutation in the CFTR gene compared with children with persistent wheezing (41.7%) or transient early wheezing (32%).
Children who wheezed at age 6 had worse lung function than those who did not wheeze, as indicated by a lower mean percent predicted FEV1, a measure of the amount of air that can be forced from the lungs in one second (91.5% vs. 100.9%).
All children who wheezed at age 6 were receiving treatment with short-acting bronchodilators versus 82.4% of those who did not wheeze. They also received inhaled steroids more frequently, yet the difference was not significant.
“While wheezing is very common in children with CF, no major determinants in children below 6 years of age could be clearly identified,” the researchers wrote.
In the second part of the study, the team drew on data from children and adolescents (35 girls and 34 boys) who were 6–17 when they attended the clinic from 2002–2011.
A positive BDR was found in 36 of 49 (73.5%) of children ages 6–8 and in 16 of 33 (48.5%) of those ages 10–12. In adolescents ages 15–17, positive BDR was found in nine of 17 participants (52.9%).
Some factors were linked to the presence of a positive BDR, but this varied with age.
In children ages 6–8, a reaction to common allergens (mites and cat and dog dander) was significantly greater in those with a positive BDR than in those without (a wheal of 4 millimeters vs. 1 mm in diameter in a skin prick test). Those with a positive BDR also had significantly lower forced vital capacity, another measure of lung function (85% vs. 101%).
In older children, ages 10–12, those with a positive BDR had a significantly higher body mass index (a measure of body fat) and lower counts of eosinophils, a type of immune cell, in the blood.
What causes wheezing in patients with CF remains unclear, the researchers noted. However, “labeling wheezing in CF as ‘CF asthma’ is misleading since the determinants are different, and may lead to inappropriate prescriptions of inhaled steroids,” they concluded.