Contemporary aminophylline use for status asthmaticus in pediatric ICUs.

An abnormally low FEV 1 /FVC ratio is universally accepted as indicative of obstructive lung disease. Clearly, the choice of cutoff to defi ne abnormality is important. The GOLD (Global Initiative for Chronic Obstructive Lung Disease) group set the lower limit of normal (LLN) at 0.7 irrespective of age, defi ning GOLD COPD stage I as FEV 1 /FVC below 0.7 and FEV 1 above 80% predicted. 1 In a recent issue of CHEST (January 2012), Mannino and Diaz-Guzman 2 argue that patients in GOLD stage I are at increased risk of premature death from respiratory causes. As shown in many publications, the 0.7 cutoff is too simplistic. After age 45, the LLN based on the fi fth centile of the FEV 1 /FVC ratio falls progressively below 0.7, meaning that the 0.7 cutoff identifi es many older patients above the LLN as false positives. Several studies have tried to validate GOLD stage I for identifying obstructive lung disease: