Prevalence, stability, and clinical significance of an isolated low FEV1 spirometry pattern in children

Abstract

Objectives: In adults, an isolated low FEV₁ pattern (an FEV₁ below the lower limit of normal with a preserved FVC and FEV₁/FVC) has been associated with the risk of developing airway obstruction. Our objective was to examine the prevalence, stability, and clinical significance of an isolated low FEV₁ pattern in the pediatric population.

Methods: We conducted a retrospective study of spirometries from children ages 6-21 years and categorized tests into spirometry patterns according to published guidelines and recent literature. In a subgroup of tests with an isolated low FEV₁ pattern, we evaluated spirometry technique. We also examined the association of having a test with an isolated low FEV₁ pattern with clinical markers of disease severity in a subgroup of children with cystic fibrosis (CF).

Results: The isolated low FEV₁ pattern was uncommon across the 29,979 tests included (n = 645 [2%]). In the 263 children with an isolated low FEV₁ pattern who had a follow-up test performed, the most frequent spirometry pattern at last test was normal (n = 123 [47%]). A primary diagnosis of CF was associated with increased odds of having at least one test with an isolated low FEV₁ pattern (OR = 8.37, 95% CI = 4.70-15.96, p < .001). The spirometry quality in a subgroup of tests with an isolated low FEV₁ pattern (n = 50) was satisfactory. In the subgroup of children with CF (n = 102), those who had a test with an isolated low FEV₁ pattern had higher odds of using oral antibiotics in the last 12 months than those who had a normal pattern (OR = 3.50, 95% CI = 1.15-10.63, p = .03).

Conclusions: The isolated low FEV₁ pattern can occur repeatedly over time, usually transitions to a normal pattern, is not due to a poor spirometry technique, and could be clinically relevant in children with chronic lung diseases.

Keywords: FEV1; children; cystic fibrosis; pulmonary function test; spirometry.