Differences in spirometry values between U.S. children 6-11 years and adolescents 12-19 years with current asthma, 2007-2010

Abstract

Background: National Asthma Education and Prevention Program (NAEPP) guidelines recommend that periodic spirometry be performed in youth with asthma. NAEPP uses different spirometry criteria to define uncontrolled asthma for children (6-11 years) and adolescents (12+ years).

Objective: To describe differences in spirometry between U.S. children and adolescents with current asthma.

Methods: We examined cross-sectional spirometry data from 453 U.S. youth with current asthma age 6-19 years from the 2007-2010 National Health and Nutrition Examination Surveys. The main outcomes were percentage predicted forced expiratory volume at 1 sec (FEV1%) ≤80 and the ratio of FEV1 to forced vital capacity (FEV1/FVC) ≤0.80. We also examined the prevalence of youth with spirometry values consistent with uncontrolled asthma, using NAEPP age-specific criteria, defined for children aged 6-11 years as FEV1% ≤80 or FEV1/FVC ≤0.80, and for adolescents aged 12-19 years as FEV1% ≤80.

Results: Children 6-11 years and adolescents 12-19 years did not differ in prevalence of FEV1% ≤80 (10.1% vs. 9.0%) or FEV1/FVC ≤0.80 (30.6% vs. 29.8%). However, based on the NAEPP age-specific criteria, 33.0% of children 6-11 years and 9.0% of adolescents 12-19 years had spirometry values consistent with uncontrolled asthma (P < 0.001).

Conclusion: Children 6-11 years and adolescents 12-19 years with current asthma did not differ in the percentage with FEV1% ≤80 or FEV1/FVC ≤0.80. However, the percent of children and adolescents with spirometry values consistent with uncontrolled asthma did differ. The difference appears to stem mainly from the different spirometry criteria for the two age groups.

Keywords: NHANES; adolescent; asthma; child; spirometry.

Fig. 1

Final sample of children and adolescents age 6–19 years with current asthma¹, NHANES 2007–2010. Abbreviations: ATS, American Thoracic Society; NHANES, National Health and Nutrition Examination Survey. ¹Current asthma defined as an affirmative response to both of the following questions: “Has a doctor or health professional ever told you that you have asthma?” and “Do you still have asthma?”Notes: ATS Criteria for effort attribute: A—All 6 quality attributes acceptable; B—Large time to, or non-repeatable, peak flow; C—Either <6 sec of exhalation or no plateau.

Fig. 2

Mutually exclusive categories of FEV1% ≤80 and FEV1/FVC ≤0.80, by age, among children and adolescents age 6–19 years with current asthma¹, US, NHANES 2007–2010. Abbreviations: FEV1, forced expiratory volume at 1 sec; FEV1%, % predicted FEV1; FVC, forced vital capacity; NHANES, National Health and Nutrition Examination Survey. ¹Current asthma defined as an affirmative response to both of the following questions: “Has a doctor or health professional ever told you that you have asthma?” and “Do you still have asthma?” Notes: Difference between children 6–11 years and adolescents 12–19 years in FEV1% ≤80 and FEV1/FVC ≤0.80 (P=0.568), FEV1/FVC ≤0.80 only (P=0.859), and FEV1% ≤80 only (P=0.709) were not statistically different. Prevalence estimates are weighted.

Fig. 3

Prevalence of spirometry values consistent with uncontrolled asthma¹, by age, among children and adolescents age 6–19 years with current asthma², US, NHANES 2007–2010. Abbreviations: FEV1, forced expiratory volume at 1 sec; FEV1%, % predicted FEV1; FVC, forced vital capacity; NH, Non-Hispanic; NHANES, National Health and Nutrition Examination Survey. ¹Uncontrolled asthma defined by spirometry based on the NAEPP age-specific criteria for uncontrolled asthma: FEV1% ≤80 or FEV1/FVC ≤0.80 for children aged 6–11 years and FEV1% ≤80 for adolescents aged 12–19 years. ²Current asthma defined as an affirmative response to both of the following questions: “Has a doctor or health professional ever told you that you have asthma?” and “Do you still have asthma?” Notes: For all (P<0.001), boys (P<0.001), non-Hispanic Whites (P <0.001), non-Hispanic Blacks (P=0.010), and Hispanics (P=0.004) the prevalence of spirometry values consistent with uncontrolled asthma between 6–11 and 12–19 year old were statistically different but it was not for girls (P=0.057). Participants with race/ Hispanic origin designated as “other” are included in totals and sex-specific analyses but not separately reported. Prevalence estimates are weighted.