Table 2—

Comparison of definitions by level of obstruction#

LLN cut-offTotal
Moderate-to-very severeMild+None§
Fixed cut-off
 Moderate-to-very severeƒ22771247403141
  • LLN: lower limit of normal (i.e. sd score of <-1.645). #: based on post-bronchodilator forced expiratory volume in one second (FEV1)/forced vital capacity (FVC) and FEV1 in all study subjects (n = 14,056); : FEV1/FVC<LLN and FEV1<LLN; +: FEV1/FVC<LLN and FEV1≥LLN; §: FEV1/FVC≥LLN; ƒ: FEV1/FVC <0.70 and FEV1 <80% of predicted value; ##: FEV1/FVC <0.70 and FEV1 ≥80% pred; ¶¶: FEV1/FVC ≥0.70.