Irreversible lung function deficits in young adults with a history of childhood asthma

Background

Asthma, traditionally characterized as reversible airway obstruction, might lead to structural changes and permanent impairment.

Objective

We sought to study the frequency, severity, and reversibility of pulmonary deficits in adults with a history of moderate-to-severe childhood allergic asthma.

Methods

Subjects (n = 121) previously enrolled in a randomized trial of immunotherapy for childhood asthma were recalled. Eighty-four young adults (age, 17-30 years; 78% male) were reevaluated by means of spirometry. Subjects with a postbronchodilator FEV₁, forced vital capacity, or FEV₁/forced vital capacity ratio less than or equal to the 5th percentile or 2 or more indices less than or equal to the 10th percentile (National Health and Nutrition Examination Survey III normative data) were invited to undergo complete pulmonary function testing, physical examination, and chest radiography after 1 week of 1 mg/kg daily prednisone.

Results

Of 84 subjects reevaluated, 40 (48%) had one or more spirometric indices less than or equal to the 5th and 10th percentiles (P < .0001). Twenty-eight of the 40 subjects were reassessed after prednisone treatment, of whom 21 (75%) did not improve. Adult and childhood (age 5-12 years) spirometric results were positively correlated (r = 0.49-0.72, P < .001). Abnormal adult spirometric results were associated with a longer duration of asthma at enrollment in the original trial (4.6 vs 6 years, P = .02), increased childhood methacholine sensitivity (PC₂₀, 0.11 vs 0.18 mg/mL; P = .01), and birth prematurity (adjusted odds ratio, 10.7; 95% CI, 1.4-84.5). Immunotherapy status was unrelated to adult lung function.

Conclusions

Many adults with a history of moderate-to-severe allergic asthma in childhood have irreversible lung function deficits. Childhood spirometry, duration of asthma, methacholine sensitivity, and birth prematurity might identify such individuals at a young age.

Key words: Childhood asthma, pulmonary function test, spirometry, methacholine sensitivity

Abbreviations used: CAMP, Childhood Asthma Management Program, CAS, Childhood Asthma Study, FVC, Forced vital capacity, OR, Odds ratio