Table 3. Subgroups analysis.

Variables	Number of cohorts	AUC (95% CI)	Variability (95% CI)	Proportion of variability likely due to threshold effect	Sensitivity (95% CI)	Specificity (95% CI)
Assays
EIA (Fujirebio)	6	0.84 (0.81–0.87)	0.97 (0.96–0.99)	1.00	0.66 (0.53–0.77)	0.87 (0.78–0.93)
CMIA (Architect)	8	0.86 (0.83–0.89)	0.97 (0.96–0.99)	0.59	0.62 (0.43–0.78)	0.88 (0.79–0.93)
Participants
Asian	10	0.85 (0.82–0.88)	0.98 (0.96–0.99)	0.08	0.66 (0.56–0.74)	0.88 (0.82–0.93)
Europe	8	0.85 (0.82–0.88)	0.98 (0.97–0.99)	0.60	0.64 (0.41–0.81)	0.88 (0.74–0.95)
Controls
HC only	7	0.92 (0.90–0.94)	0.72 (0.39–1.00)	0.13	0.66 (0.53–0.77)	0.93 (0.89–0.96)
HC and BLDS	6	0.83 (0.79–0.86)	0.82 (0.62–1.00)	0.17	0.78 (0.69–0.84)	0.74 (0.65–0.82)
BLDs only	5	0.81 (0.77–0.84)	0.96 (0.93–0.99)	0.83	0.44 (0.23–0.68)	0.91 (0.77–0.97)

AUC, area under curve; CI, confidence interval; HC, healthy control; BLDs,, benign lung diseases; CMIA, chemiluminescent immunoassay; EIA, enzyme immunoassay.