Table 2. Summary of subgroup analysis by different clinical characteristics.

Subgroup	Study (n)	Sensitivity [95% CIs]	NPV [95% CIs]	AUC [95% CIs]
IHC
No	12	0.77 [0.68–0.85]	0.91[0.87–0.94]	0.97[0.95–0.99]
Yes	41	0.88 [0.86–0.90]	0.95[0.94–0.96]	0.98[0.97–0.99]
SS
No	21	0.88[0.84–0.91]	0.93[0.91–0.95]	0.96[0.93–0.99]
Yes	32	0.87[0.84–0.90]	0.94[0.93–0.95]	0.98[0.97–0.99]
Average SLNs
Low (N<2)	4	0.84 [0.60–0.97]	0.94[0.83–0.98]	0.90[0.75–1.00]
Medium(2≤N<3)	18	0.86 [0.81–0.90]	0.95[0.93–0.96]	0.98[0.97–1.00]
High(N≥3)	16	0.88 [0.86–0.92]	0.95[0.94–0.97]	0.98[0.97–0.99]
Publication Year
Early(2000–2008)	26	0.92 [0.87–0.95]	0.94[0.91–0.96]	0.98[0.97–0.99]
Late(2009–2016)	40	0.86 [0.83–0.88]	0.94[0.93–0.95]	0.98[0.96–0.99]
SLN Tracer
Single	43	0.87 [0.84–0.90]	0.94[0.93–0.95]	0.98[0.97–0.99]
Multiple	23	0.87 [0.84–0.90]	0.94[0.93–0.96]	0.96[0.93–0.99]
Study Design
Prospective	56	0.87 [0.85–0.90]	0.94[0.93–0.95]	0.98[0.97–0.99]
Retrospective	10	0.86 [0.81–0.91]	0.95[0.93–0.96]	0.97[0.92–1.00]
Reference Test
ND	32	0.90 [0.87–0.93]	0.95[0.94–0.96]	0.97[0.95–0.98]
FU	34	0.85 [0.82–0.88]	0.94[0.92–0.95]	0.98[0.97–0.99]

ND: neck dissection; FU: follow-up; IHC: immunohistochemistry; SS: Serial sectioning; NPV: negative predictive value.