***TASK*** the task is to summarize an input biomedical literature in six sentences 
    ***INPUT*** the input is a biomedical literature 
    ***OUTPUT*** the output is the summary of an input biomedical literature in six sentences 
    ***DOCUMENTATION*** 
    ***EXAMPLES*** 
    Input: OBJECTIVES : Gastroesophageal reflux disease can be divided into three categories : nonerosive GERD ( NERD ) , erosive GERD ( ERD ) , and Barrett´s esophagus . A shift among these categories rarely occurs . The aim of the present study was to eluci date potential patient-associated risk factors associated with ERD . METHODS : A total of 6,215 patients with troublesome heartburn were recruited to a large , prospect i ve , multicenter open cohort study comprising an initial treatment phase and a 5-yr follow-up phase . Each center planned to recruit an equal number of patients with NERD and ERD . All patients underwent an interview based on st and ardized question naires , a physical examination , and endoscopy with biopsies . Data were analyzed by multiple logistic regression analysis . RESULTS : Risk factor analysis was performed on 5,289 patients ( NERD : n = 2,834 ; ERD : n = 2,455 ) , which was the intent-to-treat population excluding patients with suspected/proven complicated reflux disease . Stepwise regression analysis identified the following independent predictors of ERD : male gender , overweight , regular use of alcohol , a history of GERD > 1 yr , and smoker or ex-smoker . A higher level of education and a positive Helicobacter pylori ( H. pylori ) status were associated with a lower risk of ERD . CONCLUSIONS : Some patient-associated factors increase the risk of erosive esophagitis as opposed to nonerosive reflux disease . However , no single factor or combination of factors is capable of predicting mucosal damage with clinical ly sufficient certainty . Thus , endoscopy is still required in all GERD patients if valid information on the state of the esophageal mucosa is needed BACKGROUND Limited research has been done to explore differences between ethnic groups , including Hispanic Americans ( HAs ) , in the association between percentage body fat ( PBF ) and body mass index ( BMI ; in kg/m(2 ) ) ; the numbers of HAs are increasing in the US population . OBJECTIVE We investigated whether the relation between PBF and BMI in adult HAs differed from that of African Americans ( AAs ) and European Americans ( EAs ) . DESIGN We used a multiple regression model in which PBF measured with dual energy X-ray absorptiometry was predicted by the reciprocal of BMI ( 1/ BMI ; in m(2)/kg ) in a sample of 487 men ( n(EA ) = 192 , n(AA ) = 148 , and n(HA ) = 147 ) and 933 women ( n(EA ) = 448 , n(AA ) = 304 , and n(HA ) = 181 ) . RESULTS For men , our results showed no significant differences between HAs and EAs , AAs and EAs , or HAs and AAs in the slope of the line relating 1/ BMI to PBF . In women , there were significant differences in PBF as predicted by BMI between HAs and EAs ( P < 0.002 ) and AAs and HAs ( P = 0.020 ) , but not between AAs and EAs . When PBF was estimated on the basis of predicting equations , the trend of the predicted PBF value in women differed according to ethnic group and BMI category . At a BMI < 30 , HAs tended to have more body fat than did EAs and AAs , and at a BMI > 35 , EAs tended to have more body fat than did the other groups . CONCLUSIONS Our results show that the relation between PBF and BMI in HA women differs from that of EA and AA women AIM Gastroesophageal reflux disease ( GERD ) is a common disorder in the Western population , but detailed population -based data in China are limited . The aim of this study was to underst and the epidemiology of symptomatic gastroesophageal reflux ( SGER ) in adults of Xi'an , a northwestern city of China , and to explore the potential risk factors of GERD . METHODS Symptoms suggestive of GERD , functional dyspepsia ( FD ) , irritable bowel syndrome ( IBS ) , upper respiratory diseases and some potential risk factors were investigated in a face-to-face manner in a region-stratified r and om sample s of 2789 residents aged 18 - 70 years in Xi'an by using a st and ardized  question naire . METHODS With a response rate of 91.8 % , the prevalence of SGER was 16.98 % ( 95 % CI , 14.2 - 18.92 ) in Xi'an adults , and no gender-related difference was observed ( P<0.05 ) . SGER was more common among subjects aged 30 - 70 years than in those aged 18 - 29 years ( P<0.01 ) . The prevalence of SGER in rural , urban and suburban subjects was 21.07 % , 17.44 % and 12.12 % , respectively , and there was a significant difference between rural , urban and suburban regions ( P<0.05 ) . Compared with subjects without SGER , the prevalence of symptoms suggestive of FD and IBS , pneumonia , asthma , bronchitis , laryngitis , pharyngitis , chronic cough , wheeze , globus sensation , oral ulcer and snore was significantly increased in subjects with SGER ( P<0.01 ) . Heavy smoking ( OR=5.76 ; CI , 3.70 - 6.67 ) , heavy alcohol use ( OR=2.85 ; CI , 1.67 - 4.49 ) , peptic ulcer ( OR=5.76 ; CI , 3.99 - 8.32 ) , cerebral palsy ( OR=3.97 ; CI , 1.97 - 8.00 ) , abdominal operation ( OR=2.69 ; CI , 1.75 - 4.13 ) , obesity ( OR=2.16 ; CI , 1.47 - 3.16 ) , excessive food intake ( OR=1.43 ; CI , 1.17 - 1.15 ) , sweet food ( OR=1.23 ; CI , 0.89 - 1.54 ) , and consumption of coffee ( OR=1.23 ; CI , 0.17 - 2.00 ) were independently associated with SGER . The episodes of GERD were commonly precipitated by dietary factors ( 66.05 % ) , followed by body posture ( 26.54 % ) , ill temper ( 23.72 % ) , fatigue ( 22.32 % ) and stress ( 10.93 % ) . CONCLUSION GERD is common in Xi'an 's adult population with a mild or moderate degree . The etiology and pathogenesis of GERD are probably associated with FD , IBS , and some respiratory , laryngopharyngeal and odontostological diseases or symptoms . Some lifestyles , diseases and dietary factors are the risk factors of GERD BACKGROUND This paper reports the 3-month prevalence rates of gastrointestinal ( GI ) symptoms from the Domestic/International Gastroenterology Surveillance Study ( DIGEST ) , and their relationship with demographic factors ; namely age , gender and body mass index ( BMI ) . METHODS Subjects were recruited from 10 international sites by a total of 5581 face-to-face interviews conducted with r and omly selected members of the general population aged 18 years and over ( 50.6 % female ; mean age 44 years ) . The sample was divided according to whether subjects reported 1 or more of 14 GI symptoms , or no GI symptoms . Those with any of 11 upper GI symptoms were then subdivided according to their most bothersome symptom : gastro-oesophageal reflux (GORD)-like symptoms , ulcer-like symptoms or dysmotility-like symptoms . Symptoms were classified as relevant if they were of at least moderate severity and /or occurred at least once a week . RESULTS A mean of 46.4 % of subjects reported experiencing one or more of the 14 GI symptoms , with 28.1 % experiencing upper GI symptoms classified as relevant . Significant differences between the prevalences of relevant symptoms were evident between sampling sites . The estimated prevalence of GORD-like symptoms for the pooled sample was 7.7 % . For ulcer-like symptoms , prevalence was 4.1 % , and for dysmotility-like symptoms 15.5 % . Significant differences were observed in the prevalence rates of symptom groups between countries . Women were significantly more likely than men to experience relevant symptoms , with gender differences also observed in the rates of GORD-like and dysmotility-like symptoms . The proportion of those with relevant symptoms experiencing GORD-like symptoms increased significantly with age ; ulcer-like symptoms showed no significant relationship with age ; and dysmotility-like symptoms decreased significantly with age . The prevalence of relevant symptoms increased with increasing BMI . CONCLUSIONS In conclusion , the DIGEST has provided valuable data on the cross-country prevalence of upper GI symptoms , and their association with biological factors Abstract A r and omized chemoprevention trial on precancerous lesions of the stomach is being conducted in Tachira State , Venezuela . The aims of the study are to evaluate the efficacy of vitamin supplementation in preventing the progression rate of precancerous lesions . Here we report on the pilot phase of the study in which two antioxidant preparations were evaluated on their ability to raise antioxidant levels in plasma and in gastric juice . The study aim ed also to determine the antibiotic sensitivity profiles of Helicobacter pylori isolates prevalent in the area . Forty-three subjects with precancerous lesions ( chronic gastritis , chronic atrophic gastritis , intestinal metaplasia and dysplasia ) of the stomach were r and omized to one of two antioxidant treatments . Treatment 1 ( 250 mg of st and ard vitamin C , 200 mg of vitamin E and 6 mg of beta-carotene three times a day ) or treatment 2 ( 150 mg of st and ard vitamin C , 500 mg of slow release vitamin C , 75 mg of vitamin E and 15 mg of beta-carotene once a day ) for 7 days . Blood levels of total vitamin C , beta-carotene and alpha-tocopherol and gastric juice levels of ascorbic acid and total vitamin C were measured before and after treatment on day 8 . Both treatments increased the plasma levels of total vitamin C , beta-carotene and alpha-tocopherol/cholesterol but not those of ascorbic acid or total vitamin C in gastric juice . Treatment 1 was the best choice and result ed in a greater increase in the plasma levels of beta-carotene and alpha-tocopherol . H. pylori was cultured from 90 % of the gastric biopsies ; 35 isolates were identified which were highly resistant to metronidazole , a front-line antibiotic recommended against H. pylori in other setting A question naire study was conducted to assess the prevalence and severity of symptoms suggestive of esophageal disorders in a general population . The study included 407 r and omly selected subjects , evenly distributed in terms of sex and age , within the age span of 20 - 79 years . A total of 337 subjects replied ( 85 % ) . Symptoms suggestive of gastroesophageal reflux were found among 25 % of the participants . Cough on swallowing was common ( 27 % ) , as was globus ( 16 % ) and chest pain ( 13 % ) . In addition , dysphagia was reported by 10 % and vomiting by 9 % . The symptoms were usually mild , and moderate to severe symptoms were reported only occasionally ( 1 - 4 % ) . No statistical correlation was found between esophageal symptoms and age , sex , or the reported consumption of tobacco , alcohol , or non-steroidal anti-inflammatory drugs . The frequency of heartburn and /or acid regurgitation was twice as common among those with symptoms of respiratory disease as among those with no respiratory complaints . A stepwise logistic regression analysis showed that a chronic cough and /or breathing difficulties were significantly related to the presence of symptoms suggestive of gastroesophageal reflux We have studied the response of  erosive or ulcerative esophagitis  to treatment with omeprazole and its subsequent relapse on cessation of therapy in 196 patients . In the first phase of the study omeprazole ( 20 or 40 mg daily ) was compared with placebo in 64 patients . After 4 wk there was endoscopic healing in 81 % ( 25 of 31 ) of omeprazole-treated patients and in only 6 % ( 2 of 32 ) of placebo-treated patients . Endoscopic healing of esophagitis was accompanied by symptom relief and histologic healing of ulceration . In the second ( dose finding ) phase a further 132 patients were r and omized to omeprazole ( 20 or 40 mg daily ) and endoscopic healing was assessed . In patients with the mildest grade of ulcerative esophagitis ( grade 2 ) , healing occurred at 4 wk in 87 % receiving 20 mg and in 97 % receiving 40 mg . In patients with grade 3 esophagitis , 67 % ( 20 mg ) and 88 % ( 40 mg ) were healed . Less than half the patients with grade 4 esophagitis ( Barrett 's ulcers or 
    Output:
    
: This analysis demonstrates a positive association between increasing BMI and the presence of GERD within the United States ; this relationship became apparent only after stratification by country and level of BMI .