Table 2.

Demographic features and nodule’s size of the included studies

			Institution	Patients						Nodule size (mm)
				Male			Female		Ranges		mean ± SD or median
				n	Age (year)	n		Age (year)
[16]	Agretti et al.	2014	Academic	41	48 ± 8.6	112		45.4 ± 11.7	N/A		N/A
[17]	Rossi et al.	2016	Academic	24/60 overall FNAC	27	36/60 overall FNAC		27	5–50		N/A
[18]	Grani et al.	2016	Academic	13/47	54 ± 12	34/47		54 ± 12	N/A		N/A
[19]	Tartaglia et al.	2016	Academic	79/434 with SIAPEC 2007 and 37/216 with SIAPEC 2014	55	355/434 with SIAPEC 2007 and 179/216 with SIAPEC 2014		55	N/A		N/A
[20]	Trimboli et al.	2016	Referral	13/74 TIR3 operated	48 ± 14.5	61/74 TIR3 operated		48 ± 14.5	4–48		15.4 ± 8.6*
[21]	Straccia et al.	2017	Academic	808/4043 overall FNAC	64	3235/4043 overall FNAC		64	10–140		N/A
[22]	Censi et al.	2017	Academic	44/199	50	155/199		50	N/A		N/A
[23]	Medas et al.	2017	Academic	5/19 TIR3A and 22/83 TIR3B	N/A	14/19 TIR3A and 61/83 TIR3B		N/A	N/A		26.7 ± 14.7 TIR3A 23.4 ± 12.7 TIR3B
[24]	Ulisse et al.	2017	Academic	18/70	58	52/70		58	13–73		58
[25]	Lauria et al.	2018	Academic	199/946	56 ± 13.3	747/946		56 ± 13.3	4–56		14 ± 10
[26]	Valabrega et al.	2018	Academic	25/71	52.3	46/71		52.3	N/A		52.3
[27]	Trimboli et al.	2018	Referral	14/51 TIR3 operated	53 ± 13	37/51 TIR3 operated		53 ± 13	N/A		25.6 ± 13.5 carcinomas
[28]	Rezig et al.	2018	Academic	24	48 ± 14	72		48 ± 14	5–65		21 ± 13
[29]	Sparano et al.	2018	Academic	82/349 TIR3A	N/A	267/349 TIR3A		N/A	N/A		20.6 ± 9.5 of 289 TIR3A not operated 27.0 ± 12.8 of 60 TIR3A operated
[30]	Rullo et al.	2018	Academic	80	52.5	210		52.5	3–65		17.4
[31]	Quaglino et al.	2019	Referral	N/A	52.6	N/A		52.6	17–20		18.5
[32]	Arena and Benvenga	2019	Referral	83 overall FNACs	N/A	325 overall FNACs		N/A	N/A		N/A
[33]	Fulciniti et al.	2019	Academic	37/141	47	104/141		47	≥ 10		N/A
[34]	Straccia et al.	2019	Academic	26/86 overall FNACs	48	60/86 overall FNACs		48	4–32		N/A
[35]	Giuliano et al.	2020	Academic	129/400	46	271/400		46	18.5–26.3		N/A
[36]	Pastoricchio et al.	2020	Academic	N/A	N/A	N/A		N/A	4–60 TIR3A 4–80 TIR3B		23.4 ± 14 TIR3A 29 ± 18 TIR3B
[37]	Sponziello et al.	2020	Academic	N/A	N/A	N/A		N/A	4–64		19.62
[38]	Piccardo et al.	2020	Referral	18/111 TIR3 operated	57.6	93/111 TIR3 operated		57.6	N/A		23
[39]	Ianni et al.	2020	Academic	55/201 TIR3 operated	54.5 ± 14	146/201 TIR3 operated		54.5 ± 14	6–80 TIR3A 4–79 TIR3B		30 TIR3A 20 TIR3B
[40]	Cappelli et al.	2020	Academic	107/378 TIR3 operated	54.7 ± 13.9	271/378 TIR3 operated		54.7 ± 13.9	N/A		19.3 ± 9.2 TIR3 operated
[41]	Capezzone et al.	2021	Academic	42/188 TIR3 recorded 8/73 TIR3 operated	54.5 ± 14.0 TIR3 recorded	146/188 TIR3 recorded 21/73 TIR3 operated		54.5 ± 14.0 TIR3 recorded	7–83 TIR3 recorded		23.9 ± 12.1 TIR3 recorded
[42]	Massa et al.	2021	Academic	90/302 TIR3 recorded	53.5	212/302 TIR3 recorded		53.5	8–80 TIR3A 10–70 TIR3B		24 TIR3A 25 TIR3B
[43]	Pagano et al.	2021	Academic	35/146 overall FNACs	50.5 ± 4.8	111/146 overall FNACs		50.5 ± 14.8	N/A		26.2 ± 16.4
[44]	Possieri et al.	2021	Academic	2/19 suspicious nodules operated	45.5 ± 13.4	17/19 suspicious nodules operated		51.1 ± 15.4	≥ 10		N/A
[45]	Javalgi and Priyanka	2021	Academic	N/A	N/A	N/A		N/A	N/A		N/A
[46]	Celletti et al.	2021	Academic	39/128 TIR3 recorded	54.3	89/128 TIR3 recorded		54.3	> 15		N/A
[47]	Leni et al.	2021	Referral	108/435 patients’ final cohort	59	327/435 patients’ final cohort		59	5–70		18
[48]	Poma et al.	2021	Academic	57/151 PTC elderly 57/206 controls 6/22 elderly FTC and HTC 7/21 controls	> 65 elderly  < 65 control	94/151 PTC elderly 149/206 controls 16/22 elderly FTC and HTC 14/21 controls		> 65 elderly  < 65 control	N/A		25 ± 16 of 151 PTC elderly 21 ± 12 of 206 controls 47 ± 21 of 22 elderly FTC and HTC 25 ± 9 of 21 controls

In the column reporting the setting of institution “academic” indicates a university while “referral” indicates a public hospital. Data of this table are generally referred to the overall series of cases (patient/nodules) of each study; however, when data are referred to a subgroup, a specification is added. Data with ± refer to mean with standard deviation (SD)

PTC papillary thyroid carcinoma, FTC follicular thyroid carcinoma, HTC Hürthle cell carcinoma, N/A not available