Do NHLBI lung function criteria apply to children? A cross‐sectional evaluation of childhood asthma at National Jewish Medical and Research Center, 1999–2002

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Abstract
Although National Heart Lung Institute (NHLBI) guidelines categorize asthma severity based on spirometry, few studies have evaluated the utility of these spirometric values in grading asthma severity in children. Asthma is thought to be progressive, but little is known about the loss of lung function in childhood. This study sought to determine the spirometric indices in children from 4–18 years of age. Retrospective cross-sectional analysis was performed on all spirometries done in children at the National Jewish Medical and Research Center from 1999–2002. In total, 2,728 children performed 24,388 measures. The mean ± SD values for forced vital capacity (FVC), forced expired volume in 1 sec (FEV1), FEV1/FVC ratio, and forced expiratory flow (FEF)25–75 were 92.7 ± 16.2, 92.2 ± 18.0, 85.3 ± 9.3, and 78.0 ± 36.5 percent predicted, respectively. Seventy-seven percent of FEV1 values were ≥ 80%, 18.6% were between 60–80%, and 3.1% were 1 was highest in 5-year-old children; it declined thereafter, reaching a nadir at 11 years, followed by a partial recovery from 12–18 years. Expressed in liters, FEV1 values were lower than expected at every age, with the greatest difference at 18 years. FEV1/FVC ratios declined through childhood, suggesting impaired airway but not lung growth in children with asthma. In conclusion, the majority of asthmatic children attending a tertiary care facility had FEV1 values within normal range. With increasing age, the increase in FEV1 lags behind that of nonasthmatics, so that by 18 years, maximum FEV1 is impaired. The NHLBI FEV1 cutoff values do not appear to accurately stratify pediatric asthma, and no useful FEV1 cutoff could be generated. Pediatr Pulmonol. 2005; 39:311–317.