Barrett’s oesophagus: Evidence from the current meta-analyses

Table 1 Search terms

{“barrett’s oesophagus” (All Fields)	AND	[“meta-analysis” (Publication type)
OR “barrett esophagus” (MeSH Terms)		OR “meta-analysis as topic” (MeSH Terms)
OR [“barrett” (All Fields) AND “esophagus” (All Fields)]		OR “meta-analysis” (All Fields)]
OR “barrett esophagus”(All Fields)
OR [“barrett’s” (All Fields) AND “esophagus” (All Fields)]
OR “barrett’s esophagus” (All Fields)}
OR {“barrett’s oesophagus” (All Fields)
OR “barrett esophagus” (MeSH Terms)
OR [“barrett”(All Fields) AND “esophagus” (All Fields)]
OR “barrett esophagus”(All Fields)
OR [“barrett’s” (All Fields) AND “esophagus” (All Fields)]
OR “barrett’s esophagus”(All Fields)}

Search strategy: “Barrett’s esophagus” or “Barrett’s oesophagus”.

Table 2 Meta-analyses comparing patients with Barrett’s oesophagus to control groups

Subject	Ref.	Comparison	Group	Studies	Results	Outcome
Gender	Cook et al[6], 2005	Gender	Barrett’s	32	M:F Ratio 1.96:1 (95%CI: 1.77, 2.77)	Higher M:F ratio in Barrett’s oesophagus and reflux oesophagitis than in non-erosive reflux disease
			Erosive reflux disease	28	1.57 (95%CI: 1.40, 1.76)
			Non-erosive reflux disease	14	0.72 (95%CI: 0.62, 0.84)
Smoking	Andrici et al[7], 2013	Ever smoking	Barrett’s vs GORD	20	OR, 1.18 (95%CI: 0.75, 1.86)	Cigarette smoking associated with increased risk of Barrett’s oesophagus
			Barrett’s vs non-GORD	27	OR, 1.44 (95%CI: 1.20, 1.74)
Obesity	Cook et al[8], 2008	BMI	Barrett’s vs GORD	9	OR, 0.99/kg per m2 (95%CI: 0.97, 1.01)	Barrett’s oesophagus associated with higher BMI than control but not GORD
			Barrett’s vs general population	3	OR, 1.02/kg per m2 (95%CI: 1.01, 1.04)
	Kamat et al[9], 2009	Obesity (BMI ≥ 30 vs BMI < 30)	Barrett’s vs control (BMI ≥ 30 vs BMI < 30)	9	OR, 1.35 (95%CI: 1.15, 1.59)	Barrett’s oesophagus associated with being overweight and obese
		Overweight (BMI ≥ 25 vs BMI < 25)	Barrett’s vs control	8	OR, 1.49 (95%CI: 1.24, 1.80)
	Kubo et al[10], 2013	Waist circumference	Highest vs lowest quartiles	4	Males OR, 2.24 (95%CI: 1.08, 4.65)	Barrett’s oesophagus associated with higher waist circumference but not BMI
					Females OR, 3.75 (95%CI: 1.47, 9.56)
		BMI		4	No significant association
Symptoms of gastro-oesophageal reflux	Taylor et al[11], 2010	Symptoms of GORD	All Barrett’s vs controls	26	OR, 2.90 (95%CI: 1.86, 4.54)	Symptoms of GORD associated with all Barrett’s oesophagus, more strongly with long segment Barrett’s oesophagus than with short segment Barrett’s oesophagus
			Short segment Barrett’s vs controls	12	OR, 1.59 (95%CI: 1.07, 2.38)
			Long segment Barrett’s vs controls	11	OR, 4.16 (95%CI: 2.43, 7.12)
Helicobacter pylori	Wang et al[12]	Helicobacter pylori infection rate	Barrett’s oesophagus vs all controls	12	OR, 0.74 (95%CI: 0.40, 1.37)	Similar helicobacter pylori infection rate in Barrett’s oesophagus to all controls but lower than in endoscopically normal controls
			Barrett’s oesophagus vs endoscopically normal	9	OR, 0.50 (95%CI: 0.27, 0.93)
	Fischbach et al[13], 2012	Helicobacter pylori infection rate	Barrett’s oesophagus vs all controls	49	RR, 0.46 (9%CI: 0.35, 0.60)	Lower helicobacter infection rate in patients with Barrett’s oesophagus compared to controls
		Cag A Helicobacter pylori infection rate	Barrett’s oesophagus vs all controls	7	RR, 0.38 (95%CI: 0.19, 0.78)
Hiatus hernia	Andrici et al[14], 2012	Hiatus hernia presence	Barrett’s oesophagus vs all controls	31	OR, 3.94 (95%CI: 3.02, 5.13)	Hiatus hernia associated with Barrett’s oesophagus and more strongly associated with long-segment Barrett’s oesophagus

OR: Odds ratio; BMI: Body mass index; CI: Confidence interval.

Table 3 Meta-analyses comparing cancer risk in different groups of patients with Barrett’s oesophagus

Subject	Ref.	Comparison	Group	Studies	Results	Outcome
Medical vs surgical treatment of reflux	Corey et al[16]	Antireflux surgery vs medical treatment	Antireflux surgery	34	18 cancers/4678 patient-years (0.38% per annum)	No significant difference in cancer risk between medical and surgical antireflux therapy
			Medical therapy		26 cancers/4906 patient-years (0.53% per annum)
Endoscopic ablative therapy vs surveillance	Wani et al[25]	Non-dysplastic Barrett’s oesophagus	Surveillance	45	5.98/1000 patient-years	Endoscopic ablative therapy is effective in reducing adenocarcinoma risk in patients with non-dysplastic Barrett’s oesophagus, low-grade dysplasia and high-grade dysplasia compared to surveillance alone
			Endoscopic ablative therapy	49	1.63/1000 patient-years
		Low-grade dysplasia	Surveillance	16	16.98/1000 patient-years
			Endoscopic ablative therapy	21	1.58/1000 patient-years
		High-grade dysplasia	Surveillance	4	65.8/1000 patient-years
			Endoscopic ablative therapy	28	16.76/1000 patient-years
Demographic factors	Thomas et al[26]	Location	United Kingdom	13	7/1000 patient-years	Cancer incidence similar in all geographic areas
			United States	16	7/1000 patient years
			Europe	10	8/1000 patient-years
			Australia and New-Zealand	2	5/1000 patient-years
	Yousef et al[27]	Gender	Males	6	10.2/1000 patient-years	Cancer incidence in males is double the rate in females
			Females	5	4.5/1000 patient-years
Segment length	Thomas et al[26]	Segment length	Short segment	6	2.8/1000 patient-years	Trend for lower risk in short segment Barrett’s oesophagus (P = 0.25)
			Long segment	6	7.8/1000 patient-years
	Yousef et al[27]	Segment length	Short segment	6	6.1/1000 patient-years	Similar risk in short and long segment disease
			Long segment	26	6.7/1000 patient-years
Dysplasia	Thomas et al[26]	Low-grade dysplasia as a confounding factor	Presence of low-grade dysplasia at index endoscopy	15	P = 0.23	No significant confounding effect on cancer incidence in meta-regression analysis
Helicobacter pylori	Rokkas et al[30]	All Helicobacter pylori	Cases	10	253/757 (34.3%)	Helicobacter pylori associated with lower rate of oesophageal cancer OR, 0.52; (95%CI: 0.37, 0.73)
			Controls	10	1398/2788 (50.1%)
		Cag A Helicobacter pylori	Cases	6	120/462 (26%)	Cag A Helicobacter pylori associated with lower rate of oesophageal cancer OR, 0.51; (95%CI: 0.31, 0.82)
			Controls	6	774/1936 (40%)
Non-steroidal Anti-inflammatory drugs Statins	Wang et al[31]	Aspirin and NSAIDs vs controls		3	RR 0.64 (95%CI: 0.42, 0.96)	Lower risk of adenocarcinoma in patients taking aspirin or NSAIDs
	Alexandre et al[33]	Statins vs controls		2	RR, 0.53 (95%CI: 0.36, 0.78)	Protective effect of statins vs controls
	Singh et al[36]			5	RR, 0.57; (95%CI: 0.44, 0.75)
Statins and NSAIDs	Singh et al[36]	Combined statins and NSAIDs vs neither		2	0.28; (95%CI: 0.14, 0.56)	Protective effect of NSAIDs and statins higher than either individually

NSAIDs: Nonsteroidal antiinflammatory drugs; OR: Odds ratio; CI: Confidence interval.