RISK FACTORS ASSOCIATED WITH BARRETT'S ESOPHAGUS IN HOSPITALIZED PATIENTS

Objective: The objective of this article is to carry out a systematic review of scientific articles that reveal the risk factors associated with Barrett's esophagus in hospitalized patients. Methods: The review was performed by electronic search for articles related to risk factors associated with Barrett's esophagus in hospitalized patients. The PEO question was: What are the risk factors associated with Barrett's esophagus in hospitalized patients? The search sources were in PUBMED. The search terms were: Risk Factors; Barrett's esophagus; hospitalized patients. For this review, articles published from 2010 that had research experiences and theoretical-conceptual aspects were selected. Results: Of the 389 results found with indexing sources, a total of 25 articles were selected where 22 articles contained research results and 3 were considered for theoretical-conceptual aspects that are related to the purpose of the study. The search resulted in risk factors associated with Barrett's esophagus according to demographic characteristics and patient traits, presentation, and clinical data and lifestyles. Conclusion: An association of various risk factors with Barrett's esophagus is evidenced in hospitalized patients. The most concordant risk factors associated with Barrett's esophagus in the review were male sex, increased age, metabolic syndrome, hiatal hernia, use of proton pump inhibitors, gastroesophageal reflux (GER), obstructive sleep apnea, and erosive esophagitis.


INTRODUCTION
At present, there are several risk factors for Barrett's esophagus which have not been fully reviewed in hospitalized patients. Barrett's esophagus is an acquired esophageal condition characterized by the presence of metaplastic columnar epithelium in the distal esophagus that replaces the normal stratified squamous mucosa. Factors associated with Barrett's esophagus are symptoms of gastroesophageal reflux disease (GERD), advanced age, and male gender. Studies have revealed an association with central obesity (waist / hip ratio or abdominal circumference, but less clearly with body mass index or overall body fat content), smoking, Caucasian race, and a positive family history. In contrast, alcohol consumption does not appear to be a significant risk factor. Research has also found possible risk factors, such as metabolic syndrome, type 2 diabetes mellitus, and sleep apnea (1) .
A potential mechanism of BE pathogenesis involves transdifferentiation, in which fully differentiated esophageal squamous cells change to fully differentiated columnar cells, either directly (without undergoing cell division) or indirectly (through cell division). Although once differentiated cells are considered immutable, studies have shown that differentiated cells can be reprogrammed to acquire characteristics of immature progenitor cells. Many types of mature cells have the ability to de-differentiate into cells with progenitor cell characteristics. Therefore, trans difference in the esophagus can occur through a 2-stage GERD process in an induced reprogramming in which mature squamous cells reverse their differentiation to acquire progenitor cell plasticity before changing to a columnar phenotype (2) .
The diagnosis of Barrett's esophagus should appear to be straightforward, that means, a visible change in the lining of the distal esophagus and histologic confirmation with columnar metaplasia. Diagnostic components of Barrett's esophagus include endoscopic recognition, appropriately targeted biopsies, and histologic confirmation (3) .
The objective of this article is to carry out a systematic review of scientific articles which reveal the risk factors associated with Barrett's esophagus in hospitalized patients.  Figure 1 shows the process of selecting the terms for the systematic search.

METHODS
The search resulted in risk factors associated with Barret's esophagus according to demographic characteristics and patient traits, presentation and clinical data, and lifestyles. Table 1 shows the risk factors for Barret's esophagus in hospitalized patients from observational cohort studies and selected cases and controls for the review article.

RESULTS
A total of 389 results were obtained in the systematic search found in PUBMED and a total of 25 articles were selected where 22 articles contained research results and 3 were considered for theoreticalconceptual aspects that are related to the purpose of the study. Figure 2 shows the article selection process in PUBMED.

DISCUSSION
According to the demographic characteristics, for several authors, being a male is a risk factor for Barret's esophagus (4,5,6,7,8,9) . Although Matheus Degiovani et al, say that being a female is a risk factor for Barret's esophagus (10) .
With regard to presentation and clinical data, according to Shou-wu Lee et al and Cadman L. Leggett et al, metabolic syndrome is a risk factor for Barret's esophagus (16,17) .
Other authors have found other components of the metabolic syndrome triad as risk factors, such as Chih-Cheng Chen et al, who mentioned that central obesity is a risk factor for Barrett's esophagus (18) .
According to several authors, hiatal hernia is a risk factor for Barret's esophagus (5,611,19,20) . Although Theresa H. Nguyen distinguishes the size of the hiatal hernia considering that one greater than or equal to 3 cm is more likely to have Barret's esophagus.8 According to Yousaf Bashir Hadi et al, Cadman L. Leggett et al and Jiro Watari et al, GER is a risk factor for Barret's esophagus (4,21,22) . Although Omar Bakr et al, mentions that both the age of presentation, symptoms, family history and the number of consultations made for GER could also be risk factors (23) . Furthermore, Theresa H. Nguyen et al and Hirohiko Shinkai et al , tells us that the use of proton pump inhibitors is a risk factor for Barret's esophagus (8,15) .
Conforming to Yousaf Bashir Hadi et al, Cadman L. Leggett et al, obstructive sleep apnea is a risk factor for Barrett's esophagus (4,21) .

According to Atsuhiro Masuda et al and Hirohiko
Shinkai et al, erosive esophagitis is a risk factor for Barret's esophagus (11,15) . Although for Gloria Vargas Cárdenas et al, only the fact of having esophagitis would already be a risk factor (14) , on the other hand for Emery C Lin et al, they mention that only grade B, C, D esophagitis are a risk factor for Barret's esophagus5. Lifestyles are not as well studied as a risk factor for which more studies should be carried out.

CONCLUSION
An association of multiple risk factors with Barret's esophagus is evidenced in hospitalized patients. The risk factors associated with Barret's esophagus in the review that were the most concordant are male sex, increased age, metabolic syndrome, hiatal hernia, use of proton pump inhibitors, gastroesophageal reflux (GER), obstructive sleep apnea and erosive esophagitis.