Table 1. Characteristics of the included studies.

Source	Country	Intervention		Histology	Study design	Study period	Follow-up period	Quality score*
		LEEP	CKC
Munro 2015 [10]	Austria	107	231	ACIS	retrospective study	2001 to 2012	<1 year to 11.8 years	9
Latif 2015 [2]	USA	30	48	ACIS	retrospective study	1997 to 2011	2–168 months	9
Baalbergen 2015 [17]	Netherlands	45	65	ACIS	retrospective study	1989 to 2012	1–217 months	8
Taylor 2014 [18]	USA	15	37	ACIS	retrospective study	1998 to 2011	mean 32 months	7
Costales 2013 [12]	USA	62	110	ACIS	retrospective study	1983 to 2011	0.3–286.5 months	7
Hanegem 2012 [14]	USA	54	58	ACIS	retrospective	1998 to 2010	3–145 months	9
Kietpeerakool 2012 [13]	Thailand	34	20	ACIS	retrospective study	1998 to 2010	10–144 months	7
Costa 2012 [19]	Italy	60	74	ACIS	retrospective study	2004 to 2011	mean 40.9 months	9
DeSimone 2011 [20]	USA	17	24	ACIS	retrospective study	1990 to 2005	40 months	7
Bull-Phelps 2007 [21]	USA	32	69	ACIS	retrospective study	1993 to 2001	4–148 months	8
Hwang 2004 [22]	Canada	23	20	ACIS	retrospective study	1980 to 2002	1–248 months	6
Kennedy 2002 [23]	USA	30	27	ACIS	retrospective study	1994 to 2001	1–165 months	8
Soutter 2001 [24]	UK	43	10	ACIS	retrospective study	1986–2000	0–543 weeks	6
Kuohung 2000 [25]	USA	9	39	ACIS	retrospective study	1990 to 1999	NA	6
Azodi 1999 [26]	USA	8	25	ACIS	retrospective study	1988 to 1996	mean 38 months	9
Denehy 1997 [27]	USA	13	24	ACIS	retrospective study	1980 to 1996	1–72 months	6
Wolf 1996 [28]	USA	7	47	ACIS	retrospective study	1984 to 1993	17–132 months	9
Widrich 1996 [29]	USA	18	24	ACIS	retrospectivestudy	1980 to 1994	3–177 months	7

* Quality assessment based on the Newcastle-Ottawa Scale.

NA, not available.