Table 2. The value of ΔRV%pred, ΔTLC%pred, and ΔRV/TLC in discriminating between mild/moderate and severe/very severe COPD patients.

Variable	Cutoff Points	Sensitivity	Specificity	LR+	LR−
ΔRV%pred	63.4	0.875	0.724	3.17	0.17
ΔTLC%pred	34.2	0.931	0.796	4.56	0.09
ΔRV/TLC	10.3	0.861	0.663	2.55	0.21

LR, Likelihood Ratio; the severity of COPD was defined by GOLD classification of airflow limitation.