Table 1. Baseline Clinicopathologic Features in Patients with Papillary Thyroid Microcarcinoma According to Active Surveillance and Immediate Surgery Group.

Variable	AS (n=419)	Surgery (n=313)	P value
Age at diagnosis, yr	48.4±12.2	46.4±10.6	0.023
Age >55 years	237 (56.5)	190 (60.7)	0.289
Female sex	311 (74.4)	247 (79.4)	0.133
Maximal tumor diameter at diagnosis, mm	6.2±1.9	6.6±2.0	0.008
Maximal tumor diameter ≥7 mm	149 (35.3)	144 (46.0)	0.002
Follow-up duration, mo	6.0 (5.0–8.0)	5.0 (4.0–10.0)	<0.001
TSH, µIU/mL	1.54 (1.01–2.23)	1.28 (0.77–2.06)	0.136
Free T4, ng/dL	1.23 (1.12–1.35)	1.27 (1.04–1.41)	0.344
Total T3, ng/dL	116 (94–130)	99 (76–116)	0.707
Thyroglobulin, ng/mL	6.5 (2.7–10.9)	3.5 (0.5–9.5)	0.949

Values are expressed as mean±SD, number (%), or median (interquartile range).

AS, active surveillance; TSH, thyroid-stimulating hormone; T4, thyroxine; T3, triiodothyronine.