Table 7.

Diagnostic characteristics of the per cent predicted method, using the percentile method as a reference standard using Crapo et al (5–7) and Gutierrez et al (12) equations for all pulmonary function tests (n=3834)

Parameter	Crapo et al						Gutierrez et al
	Sen, %	Spe, %	PPV, %	NPV, %	LR+	LR–	Sen, %	Spe, %	PPV, %	NPV, %	LR+	LR−
FEV1	94	95	95	94	19	0.07	97	92	93	97	12	0.03
FVC	97	93	86	99	13	0.03	95	94	92	96	16	0.05
RV↓	100	88	42	100	9	0.00	100	86	32	100	7	0.00
RV↑	83	100	99	93	204	0.17	89	99	98	96	109	0.11
TLC↓	88	100	99	97	307	0.12	88	99	97	96	107	0.12
TLC↑	88	100	99	98	594	0.12	89	100	97	99	394	0.11
DLco	89	98	99	79	34	0.11	97	93	85	99	14	0.04

↓ Below normal;

↑ Above normal, for all other parameters, only below normal are presented; DLco Diffusing capacity of the lung for carbon monoxide; FEV1 Forced expiratory volume in 1 s; FVC Forced vital capacity; LR+ Positive likelihood ratio; LR– Negative likelihood ratio; NPV Negative predictive value; PPV Positive predictive value; RV Residual volume; Sen Sensitivity; Spe Specificity; TLC Total lung capacity