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We conducted a cross-sectional study at the Michael E. DeBakey Veterans Affairs Medical Center (MEDVAMC) in Houston, TX from February 15, 2008 to August 20, 2013 to examine risk factors for BE [25]. In brief, we invited (1) consecutive eligible patients who were scheduled for an elective esophagastroduodenoscopy (EGD) at MEDVAMC to participate in the study; and (2) randomly selected patients eligible for screening colonoscopy from seven selected primary care clinics at the same hospital, who underwent the study EGD at the same time as their screening colonoscopy. All study participants had to be 40–80 years of age (and 50–80 years for primary care patients) and undergo a study upper endoscopy. The lower age limit in the primary care group was 50 as this is the age when screening colonoscopy is recommended to commence. The purpose of enrolling patients seen in primary care was to obtain controls without BE from the source population for BE cases at the Houston VA. These controls represent patients, who, if they had BE, would be diagnosed with BE at the Houston VA. None of primary care patients were primarily referred for EGD. The patients from endoscopy clinics are symptomatic and are typically undergoing an EGD to rule out BE. The same eligibility criteria were used for both groups. Patients with a previous history of gastroesophageal surgery, previous diagnosis of cancer (esophageal, lung, liver, colon, breast or stomach), currently taking anticoagulants, with significant liver disease (as indicated by platelet count < 70,000/mL, ascites, or known gastroesophageal varices), or a history of major stroke or mental disorder were ineligible for the study. Among eligible patients in the elective EGD group, 70% completed the study (underwent the study EGD and completed the study questionnaire). In the primary care group, 43% of eligible patients completed the study; however among patients who actually underwent their colonoscopy, 85% completed the study EGD and questionnaire. This study was approved by the Institutional Review Board at Baylor College of Medicine (Board 4 for protocol H-21436) and the Office of Research and Development at MEDVAMC. Written informed consent was obtained from all participants prior to being interviewed for the study.
All study participants underwent the study EGD with systematic recording of suspected BE [26], hiatus hernia (absent, <3 cm, and ≥3 cm), and the Hill et al [27] classification of the gastroesophageal flap valve in the retroflexed endoscopic view (score range, 1–4). At least one targeted biopsy specimen was taken from suspected BE areas using jumbo biopsy forceps. BE length was determined by the Prague CM classification [26]. We performed gastric mapping by taking 7 mucosal biopsy samples from the antrum (from the greater and lesser curvatures), the corpus (from the distal greater, distal lesser, proximal greater, and proximal lesser curvatures), and the cardia [28].
For the current analysis, we performed additional review of the study histopathology reports and the electronic medical record for each study participant to define their BE cases status. For the overall analysis, we included 329 patients with BE. Where possible, we defined BE cases according to long- (≥3 cm) (n = 118) vs. short-segment (<3 cm) BE (n = 200), and newly diagnosed BE (first evidence of BE on study EGD) (n = 208) vs. prevalent BE (self-reported diagnosis of BE or history of BE diagnosis on review of the electronic medical record before the study EGD) (n = 109). A subject was considered to have definitive BE if SIM (confirmed by alcian-periodic acid-Schiff stain) under histopathologic examination was present in at least one biopsy sample obtained from tubular esophagus. Two expert pathologists reviewed all slides for suspected BE to determine the presence of SIM. Subjects with endoscopy-only BE (n = 85) were defined by the presence of suspected BE in the absence of SIM and were included in this analysis as a separate case group (“Endoscopy-only BE”).
We compared 329 BE cases separately with two control groups of patients without endoscopically suspected BE on their study EGD: (1) 503 patients recruited from primary care clinics (“Primary care controls”), representing the underlying source population from which cases arose; and (2) 1353 patients recruited from endoscopy clinics (“Endoscopy controls”), representing the population undergoing endoscopy from which cases are diagnosed.
Study participants completed a computer-assisted survey before the study EGD. The survey ascertained information about social background, lifetime history and current use of alcohol and cigarette smoking, physical activity, medical history, onset, frequency and severity of GERD symptoms, and use of medications such as H2-receptor antagonists (H2RAs), proton pump inhibitors (PPIs), and non-steroidal anti-inflammatory drugs (NSAIDs). Race and ethnicity (non-Hispanic white, black, Hispanic, Asian, or other) were self-reported on the questionnaire and verified by manual review of the VA Computerized Patient Record System (CPRS). Height and weight were measured prior to the study EGD and were used to calculate body mass index (BMI; kg/m2). We calculated waist-to-hip ratio (WHR) and categorized participants into tertiles based on the distribution of WHR in the primary care controls. H. pylori positivity was defined if organisms were seen on histopathology from any study gastric biopsy site, or if review of the medical record showed a previous positive biopsy, presence of serum antibodies, or treatment received. We examined and graded gastric biopsies for features of active and chronic gastritis and gastric atrophy according to the standardized operative link for gastritis assessment system [29], which uses the updated Sydney System [28]. A score of ≥1 on any biopsy from either the antrum or corpus was considered gastritis.
Symptoms of Gastroesophageal Reflux Disease: We ascertained a history of GERD symptoms using a slightly modified version of the validated Gastroesophageal Reflux Questionnaire [30]. We asked participants about experience of heartburn (“a burning pain or discomfort behind the breastbone in your chest”) or acid regurgitation (“a bitter or sour-tasting fluid coming up into your throat or mouth”); positive responses to these initial screening questions elicited further questions about age at onset of symptoms and frequency of symptoms at ages 10–19, 20–29, 30–49, and 50–79 years, as applicable, on a five-point ordinal scale [4]. We defined participants as never having had GERD symptoms if they reported no symptoms of heartburn or acid regurgitation at all age periods; for all other participants, frequency and severity of GERD symptoms were equal to their highest reported frequency (and severity) of either heartburn or acid regurgitation. We defined “frequent symptoms” as those occurring at least weekly. Cumulative GERD symptom duration (years) was defined as the total number of years from age 10 to age at study recruitment in which a participant had frequent GERD symptoms, and was calculated by summing all age intervals where at least weekly GERD symptoms were reported.
Chi-square tests were used to examine differences between groups for categorical variables and t-tests were used for continuous variables. We calculated odds ratios (ORs) and 95% confidence intervals (CIs) for associations between an exposure variable of interest and the risk of BE using unconditional multivariate logistic regression models. All models were adjusted for age (40–50, 50-<60, 60-<70, 70–80 years), sex and race/ethnicity (white, black, other). Statistical significance was determined at α = 0.05, and all tests for statistical significance were two-sided. All analyses were conducted using SAS version 9.4 (SAS Institute, Cary, NC).
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