Evaluation of trefoil factor 3 as a non-invasive biomarker of gastric intestinal metaplasia and gastric cancer in a high-risk population.

BACKGROUND: Adenocarcinoma is preceded by chronic atrophic gastritis, gastric intestinal metaplasia and dysplasia. Trefoil factor 3 (TFF3) is a peptide secreted by goblet cells, which is abundantly present in intestinal metaplasia. AIM: To evaluate the utility of serum TFF3 as a non-invasive biomarker for the diagnosis of intestinal metaplasia and gastric cancer. METHODS: Single-center, cross-sectional study of 274 patients who consecutively underwent upper gastrointestinal endoscopy with gastric biopsies (updated Sydney system). TFF3 levels were measured in serum by a commercial ELISA kit. Patients with normal histology or chronic atrophic gastritis without intestinal metaplasia comprised the control group. In addition, 14 patients with invasive gastric cancer were included as a reference group. The association between TFF3 levels and intestinal metaplasia was assessed by logistic regression. RESULTS: Patients with intestinal metaplasia (n=110) had a higher median TFF3 level as compared to controls (n=164), 13.1 vs. 11.9ng/mL, respectively (p=0.024). Multivariable logistic regression showed a no significant association between TFF3 levels and intestinal metaplasia (OR=1.20; 95%CI: 0.87-1.65; p-trend=0.273). The gastric cancer group had a median TFF3 level of 20.5ng/mL, and a significant association was found (OR=3.26; 95%CI: 1.29-8.27; p-trend=0.013). CONCLUSION: Serum levels of TFF3 do not discriminate intestinal metaplasia in this high-risk Latin American population. Nevertheless, we confirmed an association between TFF3 levels and invasive gastric cancer.

Proposal of minimum elements for screening and diagnosis of gastric cancer by an international Delphi consensus.

The World Endoscopy Organization Stomach and Duodenal Diseases Committee extracted minimum elements for screening and diagnosis of gastric cancer (GC) in aim to support countries that do not have national guidelines on screening and diagnosis of GC. Current national or international guidelines were collected worldwide and recommendations were classified according to the quality of evidence and were finalized through a modified Delphi method. The minimum elements consist of seven categories: [1] Extraction of high-risk patients of GC before esophagogastroduodenoscopy (EGD), [2] Patients who need surveillance of GC, [3] Method to ensure quality of EGD for detection of GC, [4] Individual GC risk assessment by EGD, [5] Extraction of high-risk patients of GC after EGD [6] Qualitative or differential diagnosis of GC by EGD, and [7] Endoscopic assessment to choose the therapeutic strategy for GC. These minimum elements will be a guide to promote the elimination of GC among countries with a high incidence of GC who lack national guidelines or screening programs.

La derivación protocolizada a endoscopía asociada a la detección de Helicobacter pylori mediante antígeno en deposiciones disminuye lista de espera para endoscopía y optimiza la detección de lesiones pre-malignas y cáncer gástrico incipiente / Protocolized referral to endoscopy and Helicobacter pylori detected in stools aimed to decrease endoscopy waiting lists

Background Chile has one of the highest mortality rates by gastric cancer (GC) worldwide. Primary prevention of GC and detection of pre-neoplastic and early neoplastic lesions should be a national priority. Aim To assess the impact of the protocolization of endoscopy referral and the use of H. pylori stool antigen test (HPSA) in the management of dyspepsia to decrease the waiting list for endoscopy and increase the detection of gastric pre-neoplastic and early neoplastic lesions. Material and Methods We included all patients referred to the Endoscopy Unit of a regional hospital, from January 2015 to December 2017. We also included patients with known pre-neoplastic lesions and all those with first degree relatives with GC. We implemented protocols for referral of patients with dyspepsia considering the use of HPSA test, prioritizing to endoscopy those with a higher risk of GC. Results A total of 4,641 endoscopies and 2,631 HPSA tests were carried out. After the adoption of these protocols, we observed a 52% decrease in the waiting time for endoscopy. The GC detection rate in this period was 1.8 to 3.1 cases per 100 endoscopies. After the adoption of the protocols, we observed a significant increase in early GC detection rate (from none in 2015 to 13% in 2017, p = 0.03). Conclusions The protocolization of the referral for endoscopy associated with widespread use of HPSA test in the management of patients with dyspepsia, are successful strategies to decrease waiting lists for endoscopy and optimize the detection rate of pre-neoplastic lesions and early GC.

Experiencia de educación continua en línea en gastroenterología para médicos no especialistas / Experience of continuing online education in gastroenterology for non specialist medical doctors

Background: Continuing education is essential for health professions and online courses can be a good way for professional development. Aim: To describe the experience with online courses for continuing education in hepatology and gastroenterology and to analyze their educational impact. Material and Methods: A three years' experience in courses on liver diseases and digestive tract is described. Their curricular design, methodology, and the educational impact was analyzed using the four levels of the Kirkpatrick's model. Results: On average, there were 321 students per course (2015-2017). 94% were Chilean and 6% from abroad (20 countries). In the educational impact analysis, in level 1 "reaction": 93% said that the course fulfilled their expectations and 92% would recommend it. In level 2 "learning": 42% approved the courses. Level 3 "behavior" was not evaluated and level 4 "organizational change" highlighted that the traditional face-to-face continuing education model of Chilean Gastroenterology Society (SChG) changed to full distance model in these three courses, with 1284 students from South America, Asia and Europe, in a 3-years-period. Additionally, these programs were included in the Medical Society of Santiago (SMS) continuing education agenda. Conclusions: The alliance between the SMS and the SChG generated on line courses that meet the educational needs of physicians and medical students, with excellent results and student perception.

[Protocolized referral to endoscopy and Helicobacter pylori detected in stools aimed to decrease endoscopy waiting lists]. / La derivación protocolizada a endoscopía asociada a la detección de Helicobacter pylori mediante antígeno en deposiciones disminuye lista de espera para endoscopía y optimiza la detección de lesiones pre-malignas y cáncer gástrico incipiente.

Background Chile has one of the highest mortality rates by gastric cancer (GC) worldwide. Primary prevention of GC and detection of pre-neoplastic and early neoplastic lesions should be a national priority. Aim To assess the impact of the protocolization of endoscopy referral and the use of H. pylori stool antigen test (HPSA) in the management of dyspepsia to decrease the waiting list for endoscopy and increase the detection of gastric pre-neoplastic and early neoplastic lesions. Material and Methods We included all patients referred to the Endoscopy Unit of a regional hospital, from January 2015 to December 2017. We also included patients with known pre-neoplastic lesions and all those with first degree relatives with GC. We implemented protocols for referral of patients with dyspepsia considering the use of HPSA test, prioritizing to endoscopy those with a higher risk of GC. Results A total of 4,641 endoscopies and 2,631 HPSA tests were carried out. After the adoption of these protocols, we observed a 52% decrease in the waiting time for endoscopy. The GC detection rate in this period was 1.8 to 3.1 cases per 100 endoscopies. After the adoption of the protocols, we observed a significant increase in early GC detection rate (from none in 2015 to 13% in 2017, p = 0.03). Conclusions The protocolization of the referral for endoscopy associated with widespread use of HPSA test in the management of patients with dyspepsia, are successful strategies to decrease waiting lists for endoscopy and optimize the detection rate of pre-neoplastic lesions and early GC.

[Recommendations of the Chilean Association for Digestive Endoscopy for the management of gastric pre-malignant lesions]. / Diagnóstico precoz de cáncer gástrico: Propuesta de detección y seguimiento de lesiones premalignas gástricas: protocolo ACHED.

An expert panel analyzed the available evidence and reached a consensus to release 24 recommendations for primary and secondary prevention of gastric cancer (CG) in symptomatic patients, with indication for upper GI endoscopy. The main recommendations include (1) Search for and eradicate H. pylori infection in all cases. (2) Systematic gastric biopsies (Sydney protocol) in all patients over 40 years of age or first grade relatives of patient with CG, to detect gastric atrophy, intestinal metaplasia or dysplasia. (3) Incorporate the OLGA system (Operative Link on Gastritis Assessment) to the pathological report, to categorize the individual risk of CG. (4) Schedule endoscopic follow-up according to the estimated risk of CG, namely annual for OLGA III- IV, every 3 years for OLGA I- II or persistent H. pylori infection, every 5 years for CG relatives without other risk factors and no follow-up for OLGA 0, H. pylori (-). (4) Establish basic human and material resources for endoscopic follow-up programs, including some essential administrative processes, and (5) Suggest the early CG/total CG diagnosis ratio of each institution and the proportion of systematic recording of endoscopic images, as quality indicators. These measures are applicable using currently available resources, they can complement any future screening programs for asymptomatic population and may contribute to improve the prognosis of CG in high-risk populations.

Management of Helicobacter pylori infection in Latin America: a Delphi technique-based consensus.

AIM: To optimize diagnosis and treatment guidelines for this geographic region, a panel of gastroenterologists, epidemiologists, and basic scientists carried out a structured evaluation of available literature. METHODS: Relevant questions were distributed among the experts, who generated draft statements for consideration by the entire panel. A modified three-round Delphi technique method was used to reach consensus. Critical input was also obtained from representatives of the concerned medical community. The quality of the evidence and level of recommendation supporting each statement was graded according to United States Preventive Services Task Force criteria. RESULTS: A group of ten experts was established. The survey included 15 open-ended questions that were distributed among the experts, who assessed the articles associated with each question. The levels of agreement achieved by the panel were 50% in the first round, 73.3% in the second round and 100% in the third round. Main consensus recommendations included: (1) when available, urea breath and stool antigen test (HpSA) should be used for non-invasive diagnosis; (2) detect and eradicate Helicobacter pylori (H. pylori) in all gastroscopy patients to decrease risk of peptic ulcer disease, prevent o retard progression in patients with preneoplastic lesions, and to prevent recurrence in patients treated for gastric cancer; (3) further investigate implementation issues and health outcomes of H. pylori eradication for primary prevention of gastric cancer in high-risk populations; (4) prescribe standard 14-d triple therapy or sequential therapy for first-line treatment; (5) routinely assess eradication success post-treatment in clinical settings; and (6) select second- and third-line therapies according to antibiotic susceptibility testing. CONCLUSION: These achievable steps toward better region-specific management can be expected to improve clinical health outcomes.

Diagnóstico de intolerancia a la lactosa en adultos: rendimiento comparativo de la clínica, test de hidrógeno espirado y test genético / Comparative performance of symptoms questionnaire, hydrogen test and genetic test for lactose intolerance

Background: Genetically programmed adult-type hypolactasia affects 56% of Chilean population. Ideally, diagnosis should be confirmed. Aim: To compare diagnostic yield of genetic test, hydrogen (H2) expiratory test and a validated symptomatic structured survey (SS). Material and Methods: Patients submitted to H2 test answered a historic (anamnestic) and current SS (after the ingestion of 25 g of lactose). A blood sample was obtained for determination of genetic polymorphisms C/T_13910, C/G_13907 and G/A_22018 by polymerase chain reaction. The gold standard for diagnosis of lactose intolerance (LI) was the agreement of at least two of three tests. Results: Sixty-one participants aged 39 ± 12 years (21 males), were studied. Anamnestic SS was diagnostic of LI in all cases (score > 7), while current SS detected LI in 27/61 (46%). H2 test (an increase > 15 ppm after ingestion of 25 g of lactose) showed LI in 31/61 (51%). The locus C/G_13907 showed no polymorphism and locus G/A_22018 was in complete linkage disequilibrium with C/T_13910. Genotype C/C_13910, associated to hypolactasia, was present in 30/58 (52%). According to the gold-standard, 32/61 (52.5%) patients were diagnosed as LI. Sensitivity and specificity were, respectively, 79% and 69% for current SS, 93% and 93% for H2 test and 97% and 93% for the genetic test. The last two showed a positive likelihood ratio (LR) > 10 and a negative LR < 0.1, figures within the range considered clinically useful. Conclusions: Genotype C/C_13910 is responsible for hypolactasia in this population. Anamnestic report of symptoms after milk ingestion and symptoms after lactose ingestion, are not accurate enough. H2 and genetic tests are simple and similarly accurate to diagnose lactose intolerance in adults.

Inverse correlation between allergy markers and Helicobacter pylori infection in children is associated with elevated levels of TGF-ß.

OBJECTIVES: We evaluated allergy/hypersensitivity clinical markers and their correlation with Helicobactor pylori infection in children and adults to analyze how early acquisition of H. pylori could modulate allergic disorder expression. PATIENTS AND METHODS: H. pylori presence was assessed by the rapid urease test and histology of antrum biopsies in 165 patients. Skin tests, serum IgE, and two clinical allergy questionnaires were performed. Allergy severity was operationally defined using a combined score. Findings were correlated with H. pylori status and cytotoxin-associated gene A presence in pediatric and adult patients. Transforming growth factor ß (TGF-ß) levels were measured by an enzyme-linked immunosorbent assay in serum and gastric biopsies of H. pylori (+) patients. RESULTS: H. pylori (-) children had more positive skin tests to a higher number of antigens than H. pylori (+) children (P<0.05). Operationally defined allergy inversely correlates with H. pylori infection in children, but not in adults. The percentage of H. pylori infection was lower in children with severe allergy (32.3%) compared with children with mild allergy (43.4%) or no allergy (64.3%) (P<0.05). Colonization with virulent strains (cytotoxin-associated gene A+) showed a nonsignificant inverse correlation with severity of allergies in pediatric patients. H. pylori-infected children, but not adults, without allergy markers showed increased levels of TGF-ß compared with allergic children both in serum and gastric mucosa (P<0.05). CONCLUSION: There was a strong inverse correlation between allergy markers and H. pylori infection in pediatric patients associated with elevated levels of TGF-ß locally and systemically. H. pylori-associated chronic gastritis might downregulate clinical allergy expression.

[Helicobacter pylori infection in symptomatic patients with benign gastroduodenal diseases: analysis of 5.664 cases]. / Infección por Helicobacter pylori en pacientes sintomáticos con patología gastroduodenal benigna: análisis de 5.664 pacientes.

UNLABELLED: Infection with Helicobacter pylori (H. pylori) is highly prevalent in Chile, but there are no systematic studies in patients with upper gastrointestinal symptoms. AIM: To determine the prevalence of H. pylori infection, according to age, gender and endoscopic pathology in a large sample of patients. METHODS: We studied 7,893 symptomatic patients submitted to upper gastrointestinal endoscopy between July 1996 and December 2003 in the context of a screening program of gastric cancer in a high risk population. H. pylori infection was determined by rapid urease test (RUT) in antral mucosa. We excluded 158 patients with gastric cancer (2%) and 2,071 patients without RUT. RESULTS: We included 5,664 patients, mean age 50.7 +/- 13.9 years, women 72.1%. Endoscopic diagnoses were normal in 59.3%, erosive esophagitis in 20%, gastric ulcer (GU) in 8.1%, duodenal ulcer (DU) in 6.4%, and erosive gastropathy in 6.2%. RUT was positive in 78% of patients. After adjusting for age and sex and with respect to patients with normal endoscopy, frequency of H. pylori infection was 86.6% in DU (OR 2.1, 95% CI 1.5-2.8, p < 0.001); 81.4% in GU (OR 1.8, 95% CI 1.4-2.4; p < 0.001 ); 79.9% in erosive gastropathy (OR 1.4, 95% CI 1.03-1.8; p = 0.03) and 77.4% in erosive esophagitis (OR 1.1, 95% CI: 0.9-1.3; p = NS). The probability of H. pylori infection decreased significantly with age, more markedly in men with normal endoscopy. CONCLUSIONS: Prevalence of H. pylori infection is very high in symptomatic Chilean patients and even higher in those with gastroduodenal ulcer or erosions, while in patients with erosive esophagitis is similar to those with normal endoscopy. The frequency of infection decreases with age, probably as a consequence of rising frequency of gastric mucosal atrophy.

Infección por Helicobacter pylori en pacientes sintomáticos con patología gastroduodenal benigna: análisis de 5.664 pacientes / Helicobacter pylori infection in symptomatic patients with benign gastroduodenal diseases: analysis of 5.664 cases

Infection with Helicobacter pylori (H. pylori) is highly prevalent in Chile, but there are no systematic studies in patients with upper gastrointestinal symptoms. Aim: To determine the prevalence of H. pylori infection, according to age, gender and endoscopic pathology in a large sample of patients. Methods: We studied 7,893 symptomatic patients submitted to upper gastrointestinal endoscopy between July 1996 and December 2003 in the context of a screening program of gastric cancer in a high risk population. H. pylori infection was determined by rapid urease test (RUT) in antral mucosa. We excluded 158 patients with gastric cancer (2 percent) and 2,071 patients without RUT. Results: We included 5,664 patients, mean age 50.7 ± 13.9 years, women 72.1 percent. Endoscopic diagnoses were normal in 59.3 percent, erosive esophagitis in 20 percent, gastric ulcer (GU) in 8.1 percent, duodenal ulcer (DU) in 6.4 percent, and erosive gastropathy in 6.2 percent. RUT was positive in 78 percent of patients. After adjusting for age and sex and with respect to patients with normal endoscopy, frequency of H. pylori infection was 86.6 percent in DU (OR 2.1, 95 percent CI 1.5-2.8, p < 0.001); 81.4 percent in GU (OR 1.8, 95 percent CI 1.4-2.4; p < 0.001 ); 79.9 percent in erosive gastropathy (OR 1.4, 95 percent CI 1.03-1.8; p = 0.03) and 77.4 percent in erosive esophagitis (OR 1.1, 95 percent CI: 0.9-1.3; p = NS). The probability of H. pylori infection decreased significantly with age, more markedly in men with normal endoscopy. Conclusions: Prevalence of H. pylori infection is very high in symptomatic Chilean patients and even higher in those with gastroduodenal ulcer or erosions, while in patients with erosive esophagitis is similar to those with normal endoscopy. The frequency of infection decreases with age, probably as a consequence of rising frequency of gastric mucosal atrophy.

[Diagnosis and management of colon perforation after colonoscopy]. / Diagnóstico y tratamiento de la perforación de colon durante la colonoscopia.

BACKGROUND: Colon perforation is an uncommon but feared complication of colonoscopy. The treatment is usually surgical but occasionally it does not require an operation. AIM: To report our experience in the diagnosis and management of colon perforation after colonoscopy. MATERIAL AND METHODS: Retrospective review of the database of 11,720 colonoscopies. The medical records of those patients that had a perforation were reviewed. RESULTS: Twelve perforations in patients aged 26 to 92 years (six women), were identified with a global perforation rate of 0.1%. Five occurred during diagnostic and seven during therapeutic procedures. All perforations were confirmed by a plain X ray or CT scan of the abdomen. Four patients, without signs of initial diffuse peritoneal irritation, were medically treated. One of these, finally required surgery. Among operated patients, a primary suture was done in five, a primary excision without colostomy in three and a Hartmann procedure due to a severe peritoneal contamination in one. No patient died. CONCLUSIONS: There is a higher risk of colon perforation during therapeutic colonoscopies. Selected cases may be safely treated without surgery.

Diagnóstico y tratamiento de la perforación de colon durante la colonoscopia / Diagnosis and management of colon perforation after colonoscopy

Background: Colon perforation is an uncommon but feared complication of colonoscopy. The treatment is usually surgical but occasionally it does not require an operation. Aim: To report our experience in the diagnosis and management of colon perforation after colonoscopy. Material and methods: Retrospective review of the database of 11,720 colonoscopies. The medical records of those patients that had a perforation were reviewed. Results: Twelve perforations in patients aged 26 to 92 years (six women), were identified with a global perforation rate of 0.1 percent. Five occurred during diagnostic and seven during therapeutic procedures. All perforations were confirmed by a plain X ray or CT scan of the abdomen. Four patients, without signs of initial diffuse peritoneal irritation, were medically treated. One of these, finally required surgery. Among operated patients, a primary suture was done in five, a primary excision without colostomy in three and a Hartmann procedure due to a severe peritoneal contamination in one. No patient died. Conclusions: There is a higher risk of colon perforation during therapeutic colonoscopies. Selected cases may be safely treated without surgery.

Gastric cancer is related to early Helicobacter pylori infection in a high-prevalence country.

BACKGROUND AND AIMS: Chile ranks fifth in the world among countries with the highest incidence of gastric cancer. The aim was to quantify the association between Helicobacter pylori infection and gastric cancer mortality at the county of residence. METHODS: A cross-sectional household survey, a probability sample of the Chilean adult population, provided 2,615 participants in whom serum H. pylori IgG antibodies were measured (ELISA). The spatial pattern of 48,367 deaths due to gastric cancer which occurred from 1985 to 2002 was analyzed using a hierarchical Poisson regression model; 333 counties were categorized as low, medium, and high gastric cancer mortality with median gastric cancer death rates of 11.4, 19.1, and 26.0 per 100,000 inhabitants, respectively. The association between H. pylori positivity and gastric cancer mortality in the county of residence was assessed by multivariate Poisson regression for complex samples. RESULTS: H. pylori prevalence was 73.0% [95% confidence intervals (CI), 70.0-76.0], higher in men [prevalence rate ratio (PRR), 1.1 (95% CI, 1.01-1.20)], peaked at ages 45 to 64, and dropped after age 65. It was higher among residents in counties with high gastric cancer mortality (79.7%; 95% CI, 76.4-82.6) compared to counties with low gastric cancer mortality (62.3%; 95% CI, 53.8-70.2; corresponding PRR, 1.3; 95% CI, 1.1-1.5); under age 24, H. pylori infection was 79.7% (95% CI, 72.2-85.6) versus 39.8% (95% CI, 19.6-64.2) among residents in counties with high and low gastric cancer mortalities, respectively (PRR, 2.0; 95% CI, 1.1-3.7). CONCLUSIONS: The high prevalence of H. pylori at younger ages was associated with high gastric cancer mortality in the base population.

Relationship between Helicobacter pylori virulence factors and regulatory cytokines as predictors of clinical outcome.

Helicobacter pylori infection is highly prevalent in Chile (73%). Usually a minority of infected patients develops complications such as ulcers and gastric cancer that have been associated with the presence of virulence factors (cagA, vacA) and host T helper response (Th1/Th2). Our aim was to evaluate the relationship between strain virulence and host immune response, using a multiple regression approach for the development of a model based on data collected from H. pylori infected patients in Chile. We analyzed levels of selected cytokines determined by ELISA (interleukin (IL)-12, IL-10, interferon (IFN)-gamma and IL-4) and the presence of cagA and vacA alleles polymorphisms determined by PCR in antral biopsies of 41 patients referred to endoscopy. By multiple regression analysis we established a correlation between bacterial and host factors using clinical outcome (gastritis and duodenal ulcer) as dependent variables. The selected model was described by: clinical outcome=0.867491 (cagA)+0.0131847 (IL-12/IL-10)+0.0103503 (IFN-gamma/IL-4) and it was able to explain over 90% of clinical outcomes observations (R(2)=96.4). This model considers that clinical outcomes are better explained by the interaction of host immune factors and strain virulence as a complex and interdependent mechanism.

Non-invasive diagnosis of gastric mucosal atrophy in an asymptomatic population with high prevalence of gastric cancer.

AIM: To validate a non-invasive method to detect gastric mucosal atrophy in a Chilean population with high prevalence of gastric cancer and a poor survival rate. METHODS: We first determined the optimal cut-off level of serum pepsinogen (PG)-1, PG-1/PG-2 ratio and 17-gastrin in 31 voluntary symptomatic patients (mean age: 66.1 years), of them 61% had histologically confirmed gastric atrophy. Then, in a population-based sample of 536 healthy individuals (209 residents in counties with higher relative risk and 327 residents in counties with lower relative risk for gastric cancer), we measured serum anti-H pylori antibodies, PG and 17-gastrin and estimated their risk of gastric cancer. RESULTS: We found that serum PG-1 < 61.5 microg/L, PG-1/PG-2 ratio < 2.2 and 17-gastrin > 13.3 pmol/L had a high specificity (91%-100%) and a fair sensitivity (56%-78%) to detect corpus-predominant atrophy. Based on low serum PG-1 and PG-1/PG-2 ratio together as diagnostic criteria, 12.5% of the asymptomatic subjects had corpus-predominant atrophy (0% of those under 25 years and 20.2% over 65 years old). The frequency of gastric atrophy was similar (12% vs 13%) but H pylori infection rate was slightly higher (77% vs 71%) in the high-risk compared to the low-risk counties. Based on their estimated gastric cancer risk, individuals were classified as: low-risk group (no H pylori infection and no atrophy; n = 115; 21.4%); moderate-risk group (H pylori infection but no atrophy; n = 354, 66.0%); and high-risk group (gastric atrophy, with or without H pylori infection; n = 67, 12.5%). The high-risk group was significantly older (mean age: 61.9+/-13.3 years), more frequently men and less educated as compared with the low-risk group. CONCLUSION: We propose to concentrate on an upper gastrointestinal endoscopy for detection of early gastric cancer in the high-risk group. This intervention model could improve the poor prognosis of gastric cancer in Chile.

CagA antibodies as a marker of virulence in chilean patients with Helicobacter pylori infection.

BACKGROUND: The bacterial and host factors that influence the clinical outcomes of the Helicobacter pylori infection have not been fully identified. Cytotoxin-associated gene product (CagA), one of the virulence factors, has been associated with a more aggressive form of infection. The authors studied the relationship between CagA status and clinical outcome in Chilean children and adults with H. pylori infection. METHODS: One hundred eighty consecutive patients undergoing upper gastrointestinal endoscopic analysis were enrolled after informed consent was obtained. Rapid urease test and histologic analysis were used to detect H. pylori infection. IgA and IgG antibodies to H. pylori whole cell antigen preparation and IgG antibodies to CagA were measured by enzyme-linked immunosorbent assay (ELISA). RESULTS: H. pylori infection was detected in 42% of the patients by biopsy or urease test and in 38% and 20% of patients by IgG and IgA antibodies, respectively. The prevalence of H. pylori either by the invasive or the serologic tests was directly related to patient age. Among patients with H. pylori, there was no significant association between age and prevalence of CagA. Nearly 70% of the patients with H. pylori and peptic ulcer disease had CagA-positive strains. In contrast, only 49% of the patients with chronic gastritis alone had CagA-positive strains (P < 0.05). CONCLUSIONS: In Chile, patients infected with H. pylori have a proportion of CagA-positive strains similar to that reported in developed countries. CagA prevalence was not significantly different in adults and children infected with H. pylori, suggesting that variations in clinical outcome may be related to host immune or environmental factors.