Table 2.

Subgroup analysis

Subgroup		No. of studies	Pooled sensitivity (95 % CI)	Pooled specificity (95 % CI)	Pooled DOR	Meta-regression RDOR	Meta-regression (p-value)
Total		6	0.983 (0.976–0.989)	0.552 (0.542–0.562)	51.020
Publication year	< 2016	2	0.976 (0.951–0.990)	0.883 (0.872–0.893)	75.907
	≥ 2016	4	0.985 (0.977–0.990)	0.308 (0.296–0.321)	31.260	0.71	0.2701
No. of nodules	< 1000	4	0.983 (0.958–0.995)	0.572 (0.535–0.608)	47.350
	≥ 1000	2	0.983 (0.976–0.989)	0.550 (0.539–0.561)	53.742	0.98	0.9301
Korea vs. other	Korea	3	0.985 (0.977–0.991)	0.261 (0.249–0.273)	22.237
	Other	3	0.978 (0.958–0.990)	0.878 (0.868–0.887)	156.13	2.14	0.0037
Reference standard	Cytology, histology	4	0.971 (0.961–0.980)	0.392 (0.379–0.405)	49.665
	Cytology, histology and US follow-up	2	0.979 (0.959–0.991)	0.874 (0.863–0.884)	118.31	0.36	0.4241
Cut–off	3/4a	2	0.979 (0.959–0.991)	0.874 (0.863–0.884)	118.31
	4/4b	4	0.971 (0.9610.980)	0.392 (0.379–0.405)	49.665	0.36	0.4241
Study design	Prospective	2	0.972 (0.944–0.989)	0.911 (0.902–0.920)	361.91
	Retrospective	4	0.985 (0.978–0.991)	0.263 (0.251–0.275)	23.023	78.61	<0.0001

CI confidence interval, DOR diagnostic odds ratio, RDOR relative diagnostic odds ratio