Table 1.

Characteristics of included studies

Reference	Inclusion period	Country	Duration of follow‐up (years)*	No. of patients	AMES criteria (low versus high risk)	No. in HT group	No. in TT ± RAI group	Matched‐pair analysis
Cross et al. 18	1940–1998	USA	15·3	962	746 low risk 207 high risk	237 (179 for analysis)	716(567 for analysis)	n.a.
Hassanain and Wexler 19	1982–2002	Canada	10 (4–25)†	180	161 low risk 17 high risk	126	54	n.a.
Lee et al. 20	1986–2006	Korea	11·8 (5–26)†	2014	n.a.	999	1015	506 HT506 TT
Kim et al. 21	2004–2008	Korea	7·0	1150	n.a.	147	1003	147 HT298 TT
Kim et al. 22	1997–2015	South Korea	5·4 (0·5–19·2)†	8676	n.a.	3289	5387	n.a.
Kwon et al. 23	1998–2007	Korea	8·5	2031	n.a.	755	1276	688 HT688 TT
Choi et al. 24	1978–2011	Korea	4·8(4·8)	5266	47 low risk 5219 high risk	974 (27 for analysis)	4292 (20 for analysis)	n.a.
Jeon et al. 25	1999–2012	Korea	7·9 (2–17·4)†	255	255 low risk	127	128	n.a.
Ji et al. 26	2001–2014	Korea	5·5	255	n.a.	82	173	66 HT66 TT
Song et al. 27	1998–2007	Korea	9·8	2345	n.a.	383	1962	381 HT381 TT

All studies had a retrospective design.

^*Values are mean(s.d.) unless indicated otherwise;

^†values are median (range). AMES, Age, Metastases, Extent and Size (risk classification); HT, hemithyroidectomy; TT, total thyroidectomy; RAI, radioactive iodine; n.a., not available.