Table 2 Sensitivity and specificity (expressed as percentage with 95% confidence intervals in parentheses) for LCI, FEV₁ and FEF₇₅ with respect to HRCT-defined structural lung abnormalities

	Bronchiectasis	HRCT score	Air trapping
LCI
Sensitivity	85 (71 to 98)	93 (83 to 100)	94 (82 to 100)
Specificity	50 (27 to 73)	65 (42 to 87)	43 (25 to 61)

FEV₁
Sensitivity	19 (4 to 34)	26 (9 to 42)	25 (4 to 46)
Specificity	89 (74 to 100)	100 (100 to 100)	89 (78 to 100)

FEF₇₅
Sensitivity	62 (43 to 80)	63 (45 to 81)	75 (54 to 96)
Specificity	83 (66 to 100)	88 (73 to 100)	75 (59 to 91)

LCI, lung clearance index; FEV₁, forced expiratory volume in 1 s; FEF₇₅, maximal expiratory flow when 75% of forced vital capacity was expired; HRCT, high-resolution CT.