From: Relationship between FEV1 change and patient-reported outcomes in randomised trials of inhaled bronchodilators for stable COPD: a systematic review
Improvement in FEV1(mL)
Number of study arms achieving SGRQ reduction, n/N (%)
4 units
3 units
≥40
17/35 (49)
21/35 (60)
≥60
14/25 (56)
18/25 (72)
≥80
12/17 (71)
14/17 (82)
≥100
12/15 (80)
14/15 (93)
≥120
8/10 (80)
9/10 (90)