Table 1.

Characteristics of studies included in the meta-analysis.

Study	Year	Region	Sample size	Study type	Mean age at diagnosis of IBD (year)	No. of patients with dysplasia and CRC	No. of IBD patients; UC, CD	Family history of CRC	Family history of IBD	Relevant degree	Proportions∗
Kisiel et al. [23]	2012	USA	77	Cohort: followed 77 IBD patients	47.6 (14.2–83.2)	31	77 UC patients under polypectomy	12	—	First	$p_1=\frac{12}{77}$
Bergeron et al. [24]	2010	France	855	Cohort: followed 855 IBD patients	33 (19-47)	14 with AL-LGDa	28	2	1	—	$p_1=\frac{2}{28};p_2=\frac{1}{14}$
						28 with CR-LGDb	56	1	4	—	$p_1=\frac{1}{56};p_2=\frac{4}{28}$
						33 with advanced neoplasia	66	0	3	—	$p_1=\frac{0}{66};p_2=\frac{3}{33}$
Baars et al. [25]	2011	Netherlands	565	Case- (CRC with IBD) control (IBD)	33 for cases, 31 for control	173 (UC:113; CD: 58; unclassified: 2)	392 (UC: 175; CD: 207; unclassified: 10)	132	—	12 first, 11 second, 109 unknown	$p_1=\frac{132}{392}$
Rubin et al. [26].	2006	USA	125	Case- (UC with developed dysplasia or CRC) control (UC without neoplasia)	29.5 for cases, 30.5 for control	26	96	9	6	First	$p_1=\frac{9}{96};p_2=\frac{6}{26}$
Lashner et al. [27]	1999	USA	95	Cohort: followed 95 UC patients	26.5 for p53-positive, 29.5 for p53-negative	36	95	1	3	—	$p_1=\frac{1}{95}$
Askling et al. [8]	2001	Sweden	8810	Cohort: followed 8810 CD patients	—	143	8810	256	—	First, second, or more	$p_1=\frac{256}{8810}$
Rutter et al. [29]	2004	England	204	Case- (CRC neoplasia) control (UC)	33 for cases, 33 for controls	68	136	18	—	First	$p_1=\frac{18}{136}$
Wu et al. [28]	2014	USA	44	Cohort: followed 44 UC patients	29.3	22 with LGD	44	—	2	First or second	$p_2=\frac{2}{22}$
					28.2	43 with adenocarcinoma and pouch dysplasia		—	4		$p_2=\frac{4}{44}$
Freire et al. [30]	2014	Portugal	76	Cross-sectional in UC	33.3	—	76	7	—	—	$p_1=\frac{7}{76}$
Connelly et al. [31]	2014	USA	82	Case- (UC with dysplasia/CRC) control (UC without dysplasia/CRC)	34.49	41	41	3	11	—	$p_1=\frac{3}{41};p_2=\frac{11}{41}$
Lutgens et al. [32]	2015	Netherlands	530	Case- (IBD-CRC) control (IBD)	27.5 for cases, 25.5 for control	188	342	18	—	First	$p_1=\frac{18}{342}$
Rubin et al. [33]	2013	USA	200	Case- (CRC and UC) control (UC	47.1	59	141	8	—	First or second	$p_1=\frac{8}{141}$
Shinozaki et al. [34]	1999	Japan	77	Case- (UC with neoplasia) control (UC)	34.3 for cases, 28.4 for control	16	61	1	—	First or second	$p_1=\frac{1}{61}$
Mooiweer et al. [35]	2013	Netherlands	1018	Cohort: followed 1018 IBD patients	47.7	11	1018	32	—	First	$p_1=\frac{32}{1018}$
Velayos et al. [36]	2006	USA	376	Case- (UC with CRC) control (UC)	25 for cases, 27 for control	188	188	6	—	First	$p_1=\frac{6}{188}$
Askling et al. [20]	2001	Sweden	31093	Cohort: followed 31093 IBD patients	37.65	560	13186	234	—	First, second or more	$p_1=\frac{234}{13186}$
Eaden et al. [37]	2000	Sweden	204	Case- (UC, CRC) control (UC)	57.4 at diagnosis of CRC	102	102	2	5	First	$p_1=\frac{2}{102};p_2=\frac{5}{102}$
Bopanna et al. [38]	2016	India	28	Cross-sectional in UC	28.89	—	28	0	—	—	$p_1=\frac{0}{28}$
Parian et al. [39]	2016	USA	187	Cross-sectional in UC	36.7 for UC with dysplasia, 29.7 for UC without dysplasia	39	148	12	7	First	$p_1=\frac{12}{148};p_2=\frac{7}{39}$
Rini et al. [40]	2008	USA	223	Cross-sectional in IBD	43.94	—	223: 136 UC, 55 CD, 32 unknown	15 in first degree; 34 in second or more	—	First, second, or more	$p_1=\frac{49}{223}$
Tang et al. [21]	2010	USA	48	Case- (IBD with CRC) control (IBD)	36.6 for cases, 34.7 for control	18	30	3	3	First, second, or more	$p_1=\frac{3}{30};p_2=\frac{3}{18}$
Lakatos et al. [41]	2006	Hungary	723	Cohort: followed 723 UC	49	13	723	—	0	—	$p_2=\frac{0}{13}$
Lashner [42]	1993	USA	67	Case- (UC with dysplasia and CRC) control (UC)	—	6	61	7	2	—	$p_1=\frac{7}{61};p_2=\frac{2}{6}$
Derikx et al. [43]	2014	Netherlands	124	Case- (IBD with carcinoma and dysplasia) control (IBD)	25.7 for cases, 25.7 for control	25	99	0	—	—	$p_1=\frac{0}{99}$
Lashner et al. [22]	1997	USA	98	Case- (UC with CRC or dysplasia) control (UC without CRC or dysplasia)	25.8 for CRC or dysplasia, 29.5 for no dysplasia	29	69	1	1	—	$p_1=\frac{1}{69};p_2=\frac{1}{29}$
Brackmann et al. [19]	2009	Norway	67	Cohort: followed 67 IBD with CRC	25	67	67	6	5	First, second or more	$p_1=\frac{6}{67};p_2=\frac{5}{67}$
Adams et al. [44]	2013	USA	7202	Cohort: followed 7202 CRC cases	—	7202	250	35	—	First	$p_1=\frac{35}{250}$

^∗ p ₁ = patient with family history of CRC/patient with IBD; p₂ = patient with family history of IBD/patient with dysplasia or CRC; ^aadenoma-like low-grade dysplasia; ^bcolitis-related low-grade dysplasia.