Study design in evidence-based surgery:What is the role of case-control studies?

Randomized controlled trials(RCTs) are the gold standard in terms of study design, however, in the surgical setting conducting RCTs can often be unethical or logistically impossible. Case-control studies should become the major study design used in surgical research when RCTs are unable to be conducted and definitely replacing case series which offer little insight into surgical outcomes and disease processes.

Multicenter case-control study of the risk factors for ulcerative colitis in China

AIM:To evaluate potential risk factors in the development of ulcerative colitis(UC) in China.METHODS:A total of 1308 patients with UC and 1308 age-matched and sex-matched controls were prospectively studied in China.The UC cases were collected from 17 hospitals in China from April 2007 to April 2010.Uniform questionnaires were designed to investigate risk factors including smoking,appendectomy,stress,socio-economic conditions,nonsteroidal antiinflammatory drugs(NSAIDs),oral contraceptives,diet,breastfeeding,infections and family sanitary conditions.Group comparisons by each factor were done using simple logistic regression analysis.Conditional logistic regression was used for multivariate analysis.RESULTS:By univariate analysis,the variables predictive of UC included feeling stress,light and heavy alcoholic drinking,spicy food,sugar consumption and infectious diarrhea,while heavy tea intake and tap water consumption were protective against UC.On multivariate analysis,the protective factor for UC was tap water consumption [odds ratios(OR) = 0.424,95%CI:0.302-0.594,P < 0.001];while the potential risk factors for UC were heavy sugar consumption(OR = 1.632,95%CI:1.156-2.305,P < 0.001),spicy food(light intake:OR = 3.329,95%CI:2.282-4.857,P < 0.001;heavy intake:OR = 3.979,95%CI:2.700-5.863,P < 0.001),and often feeling stress(OR = 1.981,95%CI:1.447-2.711,P < 0.001).Other factors,such as smoking habit,appendectomy,breastfeeding,a history of measles,rural or urban residence,education,oral contraceptives,and NSAID use have not been found to have a significant association with the development of UC in the present study.CONCLUSION:Our study showed tap water consumption was a protective factor for UC,while spicy food,heavy sugar consumption and often feeling stress were risk factors for UC in this Chinese population.

Risk factors for alcohol-related liver injury in the island population of China: A population-based case-control study

AIM:To investigate the association of alcohol dose, duration of drinking and obesity with abnormal alcohol-related liver injury indicators, the prevalence of alcohol-related liver injury in the island population of China.METHODS:Randomized multistage stratified cluster sampling from the island population of China was used in the population-based case-control study. Then interview, physical examination, laboratory assessments and ultrasonography were done. RESULTS:Daily alcohol intake ≥ 20 g, duration of drinking ≥ 5 years and obesity were closely related to alcohol-related liver injury (P < 0.05). The odds-ratio (OR) (95% CI) was 1.965 (1.122-3.442), 3.412 (1.789-6.507) and 1.887 (1.261-2.824), respectively. The prevalence rate of alcohol-related liver injury in ≥ 20 g daily alcohol intake group and < 20 g daily alcohol intake group was 37.14% and 12.06%, respectively. The prevalence rate of alcohol-related liver injury in ≥ 5 years drinking group and < 5 years drinking group was 34.44% and 8.53%, respectively. No significant dose-response relation was found between daily alcohol intake and abnormal alcohol-related liver injury indicators as well as between duration of drinking and abnormal alcohol-related liver injury indicators. There was no significant difference in the prevalence of alcohol-related liver injury between beer drinking group and yellow rice wine drinking group, hard liquor drinking group, multiple drinking group.CONCLUSION:The risk threshold of daily alcohol intake is 20 g and duration of drinking inducing alcohol-related liver injury 5 years in the island population of China. Liver injury induced by obesity should be concerned.

Risk factors of intrahepatic cholangiocarcinoma in patients with hepatolithiasis:a case-control study

BACKGROUND:Why 3.3% to 10% of all patients with hepatolithiasis develop intrahepatic cholangiocarcinoma (ICC) remains unknown.We carried out a hospital-based case-control study to identify risk factors for the development of ICC in patients with hepatolithiasis in China.METHODS:Eighty-seven patients with pathologically diagnosed hepatolithiasis associated with ICC and 228 with hepatolithiasis alone matched by sex,age (±2 years),hospital admittance and place of residence were interviewed during the period of 2000-2008.Odds ratios (OR) and 95% confidence intervals (CI) were calculated for each risk factor.RESULTS:Among the patients with hepatolithiasis associated with ICC,the mean age was 57.7 years and 61.0% were female Univariate analysis showed that the significant risk factors for ICC development in hepatolithiasis were smoking,family history of cancer,appendectomy during childhood (under age 20),and duration of symptoms >10 years.In multivariate stepwise logistic regression analysis,smoking (OR=1.931,95% CI:1.000-3.731),family history of cancer (OR=5.175,95% CI:1.216-22.022),and duration of symptoms >10 years (OR=2.348 95% CI:1.394-3.952) were independent factors.CONCLUSION:Smoking,family history of cancer and duration of symptoms >10 years may be risk factors for ICC in patients with hepatolithiasis.

Barriers to colorectal cancer screening:A case-control study

AIM:To investigate barriers to colorectal cancer(CRC) screening in a community population.METHODS:We conducted a community-based case-control study in an urban Chinese population by questionnaire.Cases were selected from those completing both a fecal occult blood test(FOBT) case and colonoscopy in a CRC screening program in 2004.Control groups were matched by gender, age group and community.Control 1 included those having a positive FOBT but refusing a colonoscopy.Control 2 included those who refused both an FOBT and colonoscopy.RESULTS:The impact of occupation on willingness to attend a colorectal screening program differed by gender.P for heterogeneity was 0.009 for case vs control group 1, 0.01 for case versus control group 2, and 0.80 for control group 1 vs 2.Poor awareness of CRC and its screening program, characteristics of screening tests, and lack of time affected the screening rate.Financial support, fear of pain and bowel preparation were barriers to a colonoscopy as a screening test.Eighty-two percent of control group 1 and 87.1% of control group 2 were willing attend if the colonoscopy was free, but only 56.3% and 53.1%, respectively, if it was self-paid.Multivariate odds ratios for case vs control group 1 were 0.10 among those unwilling to attend a free colonoscopy and 0.50 among those unwilling to attend a self-paid colonoscopy.CONCLUSION:Raising the public awareness of CRC and its screening, integrating CRC screening into the health care system, and using a painless colonoscopy would increase its screening rate.

A nested case-control study of maternal-neonatal transmission of hepatitis B virus in a Chinese population

AIM:To examine the determinants of maternal-neonatal transmission of hepatitis B virus(HBV) METHODS:A nested case-control study was conducted in Changsha,Hunan,People's Republic of China from January 1,2005 to September 31,2006 To avoid potential maternal blood contamination,we collected vein blood of newborns immediately after birth and before initial hepatitis B vaccination to determine the HBV infection status of the newborn For each HBsAg-positive infant,one HBsAg-negative infant born to an HBsAg-positive mother was matched by hospital at birth(same),gender(same),and date of birth(within 1 mo) A faceto-face interview was conducted to collect clinical and epidemiological data Conditional logistic regression analysis was used to estimate the independent effects of various determinants on maternal-neonatal transmission of HBV RESULTS:A total of 141 HBsAg-positive infants and 141 individually matched HBsAg-negative infants were included in the final analysis Maternal first-degree family history of HBV infection,intrahepatic cholestasis,and premature rupture of membranes were risk factors for perinatal transmission of HBV,whereas systematic treatment and HBV immunoglobulin injections for mothers with HBV infection were protective factors for maternal-neonatal transmission of HBV,after adjustment for potential confounding factors CONCLUSION:For HBsAg-positive mothers,systematic treatment,HBV immunoglobulin administration,and controlling intrahepatic cholestasis and pregnancy complications may reduce the incidence of perinatal transmission of HBV.

TNF-α and IL-1RA Polymorphisms and Silicosis Susceptibility in Chinese Workers Exposed to Silica Particles:A Case-Control Study

Abstract Objective To assess the association of TNF-α and IL-1RA SNPs with the risk of silicosis in Chinese workers exposed to silica particles. Methods Case-control study design was used to enroll 68 silicotic patients induced by silica particles and 68 healthy workers matched for length of silica particle exposure as controls. Both cases and controls were from the same company in southwest China, and each of them was requested to complete a questionnaire. Blood samples were drawn for genomic DNA extraction from each participant. The genotyping of TNF-α （-238 and -308） and IL-1RA （＋2018） was performed using polymerase chain reaction-based restriction fragment length polymorphism （PCR-RFLP） and SYBR green-based quantitative polymerase chain reaction {qPCR）, respectively. Unconditional logistic regression model was used to estimate odds ratios （ORs） and their 95% confidential intervals （Cl） for SNPs. Results No significant differences were found between cases and controls in particles exposure length, body mass index （BMI）, and status of smoking and alcohol consumption except for age （P=O.O01） and blood type （P=0.042）. The frequencies of TNF-c（（-238） and IL-1RA （＋2018） genotypes in cases were significantly different from those in controls, （P=O.O01 and P=0.O02, respectively）, while a borderline significant difference was found in the frequencies of TNF-α（-308） between cases and controls （P=0.063）. The variants of three SNPs increased the risk of silicosis in the Chinese workers exposed to silica particles. The adjusted ORs of TNFα（-308）, TNF-α（-238） and IL-1RA （＋2018） were 2.8 （95% Ch 2.1-7.5）, 20.9 （95% Ch 2.8-236.4） and 4.0 （95% CI： 2.6-10.2）, respectively. Conclusion It is suggested that cytokine polymorphisms of TNF-ct （-238, -308） and IL-1RA （＋2018） are associated with the risk of silicosis in the Chinese workers exposed to silica particles. Further independent studies on the interaction between SNPs and exposure to silica particles with a larger sample size are therefore warranted.

Risk Factors of Low Back Pain among the Chinese Occupational Population:A Case-control Study

Objective To explore the risk factors of low back pain among the Chinese occupational population in several major industries. Methods A total of 7200 subjects （3600 cases and 3600 controls） were randomly sampled from a cross-sectional study, and they were investigated for individual and occupational factors of low back pain. The potential risk factors were first selected by using chi-square tests. Secondly, collinearity diagnosis proceeded by using the Kendall＇s rank correlation. Finally, binary logistic regression model was used for multi-factor analysis. Results Collinearity diagnosis showed that there was a severe collinearity problem among the potential risk factors of low back pain. Logistic regression model included 20 variables with statistical significance. Bending neck forward or holding neck in a forward posturefor long periods （0R=1.408） was the most important risk factor inducing low back pain in this study, followed by bending heavily with the trunk （0R=1.402）, carrying out identical work almost for the whole day （0R=1.340）. Additionally, suHicient normal break was a protective factor of low back pain. Conclusion Low back pain among the Chinese occupational population was associated with body height, occupation, work organization, physical work, working posture, and others. All these risk factors could be regarded as the indicators of low back pain, and some relevant preventive measures should be taken to reduce low back pain risk.

Risk of Active Pulmonary Tuberculosis among Patients with Coal Workers'Pneumoconiosis:A Case-control Study in China

The aim of this study was to estimate the association between occupational, environmental, behavioral risk factors, and active pulmonary tuberculosis（PTB） among coal workers＇ pneumoconiosis（CWP） patients. A matched case-control study was conducted in 86 CWP patients with active PTB and 86 CWP controls without TB. A standardized questionnaire was used for risk factors assessment. Conditioned logistic regression analysis was used to identify associations between the risk factors and active PTB among CWP patients. The results showed that the stage of CWP, poor workplace ventilation, family history of TB, and exposure to TB were independent risk factors for active PTB in patients with CWP with which recommendations for improving work environments, and for case finding activities in patients with CWP could be made.

Risk of colorectal polyps in patients with sporadic gastric polyps:A case-control study

AIM:To assess the risk of colonic polyps,adenomas and advanced neoplastic lesions(ANL) in patients with sporadic gastric polyps,especially those with fundic gland polyps(FGP).METHODS:Clinical records of patients who had performed an upper and a lower digestive endoscopy between September 2007 and August 2008 were retrospectively analyzed.A case-control study was carried out,calling patients with gastric polyps as 'cases' and patients without gastric polyps as 'controls'.The risk of colonic polyps,adenomas and ANL(villous component ≥ 25%,size ≥ 10 mm,or high grade dysplasia) was assessed [odds ratio(OR) and its corresponding 95%CI].RESULTS:Two hundred and forty seven patients were analyzed:78 with gastric polyps(cases) and 169 without gastric polyps(controls).Among the cases,the majority of gastric polyps were FGP(80%,CI:69-88) and hyperplastic(20%,CI:12-31);25% had colonic polyps(25% hyperplastic and 68% adenomas,from which 45% were ANL).Among the controls,20% had colonic polyps(31% hyperplastic and 63% adenomas,from which 41% were ANL).The patients with sporadic FGP had an OR of 1.56(CI:0.80-3.04) for colonic polyps,an OR of 1.78(CI:0.82-3.84) for colonic adenomas,and an OR of 0.80(CI:0.21-2.98) for ANL.Similar results were found in patients with gastric polyps in general.CONCLUSION:The results of this study did not show more risk of colorectal adenomas or ANL neither in patients with sporadic gastric polyps nor in those with FGP.

Nested case-control study on risk factors for opportunistic infections in patients with inflammatory bowel disease

BACKGROUND When opportunistic infections occur, patients with inflammatory bowel disease(IBD) commonly display a significantly increased rate of morbidity and mortality.With increasing use of immunosuppressive agents and biological agents,opportunistic infections are becoming a hot topic in the perspective of drug safety in IBD patients. Despite the well-established role of opportunistic infections in the prognosis of IBD patients, there are few epidemiological data investigating the incidence of opportunis-tic infections in IBD patients in China. Besides, the risk factors for opportunistic infection in Chinese IBD patients remain unclear.AIM To predict the incidence of opportunistic infections related to IBD in China, and explore the risk factors for opportunistic infections.METHODS A single-center, prospective study of IBD patients was conducted. The patients were followed for up to 12 mo to calculate the incidence of infections. For each infected IBD patient, two non-infected IBD patients were selected as controls. A conditional logistic regression analysis was used to assess associations between putative risk factors and opportunistic infections, which are represented as odds ratios(OR) and 95% confidence intervals(CIs).RESULTS Seventy(28.11%) out of 249 IBD patients developed opportunistic infections.Clostridium difficile infections and respiratory syncytial virus infections were found in 24 and 16 patients, respectively. In a univariate analysis, factors such as the severity of IBD, use of an immunosuppressant or immunosuppressants, high levels of fecal calprotectin, and C-reactive protein or erythrocyte sedimentation rate were individually related to a significantly increased risk of opportunistic infection. Multivariate analysis indicated that the use of any immunosuppressant yielded an OR of 3.247(95%CI: 1.128-9.341), whereas the use of any two immunosuppressants yielded an OR of 6.457(95%CI: 1.726-24.152) for opportunistic infection. Interestingly, when immunosuppressants were used in combination with infliximab(IFX) or 5-aminosalicylic acid, a significantly increased risk of opportunistic infection was also observed. The relative risk of opportunistic infection was greatest in IBD patients with severe disease activity(OR = 9.090; 95%CI: 1.532-53.941, relative to the remission stage). However, the use of IFX alone did not increase the risk of opportunistic infection.CONCLUSION Factors such as severe IBD, elevated levels of fecal calprotectin, and the use of immunosuppressive medications, especially when used in combination, are major risk factors for opportunistic infections in IBD patients. The use of IFX alone does not increase the risk of opportunistic infection.

Association between PPARG genetic polymorphisms and ischemic stroke risk in a northern Chinese Han population: a case-control study

Two common polymorphisms of the peroxisome proliferator-activated receptor gamma(PPARG) gene, rs1801282 and rs3856806, may be important candidate gene loci affecting the susceptibility to ischemic stroke. This case-control study sought to identify the relationship between these two single-nucleotide polymorphisms and ischemic stroke risk in a northern Chinese Han population. A total of 910 ischemic stroke participants were recruited from the First Hospital of China Medical University, Shenyang, China as a case group, of whom 895 completed the study. The 883 healthy controls were recruited from the Health Check Center of the First Hospital of China Medical University, Shenyang, China. All participants or family members provided informed consent. The study protocol was approved by the Ethics Committee of the First Hospital of China Medical University, China on February 20, 2012(approval No. 2012-38-1). The protocol was registered with the Chinese Clinical Trial Registry(registration number: ChiCTR-COC-17013559). Plasma genomic DNA was extracted from all participants and analyzed for rs1801282 and rs3856806 single nucleotide polymorphisms using a SNaPshot Multiplex sequencing assay. Odds ratios(ORs) and 95% confidence intervals(CIs) were calculated using unconditional logistic regression to estimate the association between ischemic stroke and a particular genotype. Results demonstrated that the G allele frequency of the PPARG gene rs1801282 locus was significantly higher in the case group than in the control group(P < 0.001). Individuals carrying the G allele had a 1.844 fold increased risk of ischemic stroke(OR = 1.844, 95% CI: 1.286–2.645, P < 0.001). Individuals carrying the rs3856806 T allele had a 1.366 fold increased risk of ischemic stroke(OR = 1.366, 95% CI: 1.077–1.733, P = 0.010). The distribution frequencies of the PPARG gene haplotypes rs1801282-rs3856806 in the control and case groups were determined. The frequency of distribution in the G-T haplotype case group was significantly higher than that in the control group. The risk of ischemic stroke increased to 2.953 times in individuals carrying the G-T haplotype(OR = 2.953, 95% CI: 2.082–4.190, P < 0.001). The rs1801282 G allele and rs3856806 T allele had a multiplicative interaction(OR = 3.404, 95% CI: 1.631–7.102, P < 0.001) and additive interaction(RERI = 41.705, 95% CI: 14.586–68.824, AP = 0.860;95% CI: 0.779–0.940;S = 8.170, 95% CI: 3.772–17.697) on ischemic stroke risk, showing a synergistic effect. Of all ischemic stroke cases, 86% were attributed to the interaction of the G allele of rs1801282 and the T allele of rs3856806. The effect of the PPARG rs1801282 G allele on ischemic stroke risk was enhanced in the presence of the rs3856806 T allele(OR = 8.001 vs. 1.844). The effect of the rs3856806 T allele on ischemic stroke risk was also enhanced in the presence of the rs1801282 G allele(OR = 2.546 vs. 1.366). Our results confirmed that the G allele of the PPARG gene rs1801282 locus and the T allele of the rs3856806 locus may be independent risk factors for ischemic stroke in the Han population of northern China, with a synergistic effect between the two alleles.

Environmental and Psycho-social Factors Related to Prostate Cancer Risk in the Chinese Population:a Case-control Study

Objective To study the risk environmental and psycho-social factors associated to prostate cancer （PCa） in Chinese population. Methods 250 PCa patients and 500 controls were enrolled in this case-control study. Information was collected and logistic regression analysis was used to estimate the odds ratios （OR） and 95% confidence intervals （95% CI） for relationship between lifestyle, eating habits and psycho-social factors with PCa risk. Results Green vegetables and green tea were associated with a decreased risk of PCa （0R=0.39, 95% CI： 0.28-0.53; 0R=0.59, 95% Cl： 0.40-0.87, respectively）. Family history of PCa （0R=7.16, 95% CI： 2.01-25.49）, history of prostate diseases （0R=2.28, 95% Cl： 1.53-3.41）, alcohol consumption （0R=1.97, 95% CI： 1.33-2.90）, red meat consumption （0R=1.74, 95% CI： 1.20-2.52）, barbecued （0R=2.29, 95% CI： 1.11-4.73） or fried （0R=2.35, 95% CI： 1.24-4.43） foods were related with increased PCa risk. Negative psycho-social factors including occupational setbacks （0R=1.61, 95% CI： 2.00-2.59）, marital separation （0R=1.94, 95% CI： 1.29-2.91）, self-contained suffering {0R=2.37, 95% CI： 1.58-3.55）, and high sensitivity to the personal comments （0R=1.73, 95% CI： 1.18-2.54） were related to PCa. Conclusion Regular consumption of green vegetables and green tea may suggest protective effects on PCa. Alcohol consumption, red meat consumption and barbecued or fried foods were associated with PCa. Negative psycho-social factors may also play a role in the incidence of PCa in Chinese population.

Statin use and the risk of colorectal cancer: A population-based case-control study

AIM: To investigate whether the use of statins is associated with colorectal cancer risk. METHODS: We conducted a population-based case-control study in Taiwan. Data were retrospectively collected from the Taiwan National Health Insurance Research Database. Cases consisted of all patients who were aged 50 years and older and had a first-time diagnosis of colorectal cancer between the period 2005 and 2008. The controls were matched to cases by age, sex, and index date. Adjusted odds ratios (ORs) and 95% confidence intervals (CIs) were estimated using multiple logistic regression. RESULTS: We examined 1156 colorectal cancer cases and 4624 controls. The unadjusted ORs for any statin prescription was 1.10 (95% CI = 0.94-1.30) and the adjusted OR was 1.09 (95% CI = 0.91-1.30). When statin use was categorized by cumulative dose, the adjusted ORs were 0.99 (95% CI = 0.78-1.27) for the group with cumulative statin use below 105 defined daily doses (DDDs); 1.07 (95% CI = 0.78-1.49) for the group with cumulative statin use between 106 and 298.66 DDDs; and 1.30 (95% CI = 0.96-1.75) for the group with cumulative statin use of 298.66 DDDs or more compared with nonusers. CONCLUSION: This study does not provide support for a protective effect of statins against colorectal cancer.

Diagnostic value of interleukin-8 in colorectal cancer:A case-control study and meta-analysis

AIM: To assess the diagnostic value of serum interleukin-8 (IL-8) in the detection of colorectal cancer (CRC).

Insulin-like growth factor-1, IGF binding protein-3, and the risk of esophageal cancer in a nested case-control study

To assess the relationship between serum levels of insulin-like growth factor-1 (IGF1)/IGF-binding protein-3 (IGFBP3) and the risk of esophageal carcinoma.METHODSWe assessed the relationship between the serum levels of these molecules and the risk of esophageal cancer in a prospective, nested case-control study of participants from the Japan Collaborative Cohort Study. A baseline survey was conducted from 1988 to 1990. Of the 110585 enrolled participants, 35% donated blood samples. Those who had been diagnosed with esophageal cancer were considered cases for nested case-control studies. A conditional logistic model was used to estimate odds ratios for the incidence of esophageal cancer associated with serum IGF1 and IGFBP3 levels.RESULTSThirty-one cases and 86 controls were eligible for the present assessment. The molar ratio of IGF1/IGFBP3, which represents the free and active form of IGF1, was not correlated with the risk of esophageal carcinoma. A higher molar difference between IGFBP3 and IGF1, which estimates the free form of IGFBP3, was associated with a decreased risk of esophageal carcinoma (P = 0.0146), and people in the highest tertile had the lowest risk (OR = 0.107, 95%CI: 0.017-0.669). After adjustment for body mass index, tobacco use, and alcohol intake, the molar difference of IGFBP3-IGF1 was inversely correlated with the risk of esophageal carcinoma (P = 0.0150).CONCLUSIONThe free form of IGFBP3, which is estimated by this molar difference, may be inversely associated with esophageal cancer incidence.

Mass screening-based case-control study of diet and prostate cancer in Changchun, China

Aim： To investigate possible correlation factors for prostate cancer by a population-based case-control study in China. Methods： We carded out a mass screening of prostate cancer in Changchun, China, using a prostate-specific antigen assisted by Japan International Cooperation Agency. From June 1998 to December 2000, 3 940 men over 50 years old were screened. Of these, 29 men were diagnosed with prostate cancer. We selected 28 cases and matched them with controls of low prostate-specific antigen value （〈 4.1 ng/mL） by 1：10 according to age and place of employment. A case-control study of diet and prostate cancer was then carded out. Results： After adjustment for education, body mass index （BMI）, smoking, alcohol consumption, marriage and diet, intake of soybean product was discovered to be inversely related to prostate cancer. Men who consumed soybean product more than twice per week on different days had a multivariate odds ratio （OR） of 0.38 （95% confidence interval [CI], 0.13-1.12）. In addition, men who consumed soybean products more than once per day had a multivariate OR of 0.29 （95% CI, 0.11-0.79） compared with men who consumed soybean products less than once per week. The P for trend was 0.02, which showed significant difference. There was no significant difference in P trend for any dairy food. Even when we matched the cases and controls by other criteria, we found that soybean food was the only preventive factor associated with prostate cancer. Conclusion： Our study suggests that consumption of soybeans, one of the most popular foods in Asia, would decrease the risk of prostate cancer.

Glutathione S-transferases M1,T1 genotypes and the risk of gastric cancer:A case-control study

AIM: Glutathione S-transferases (GSTs) are involved in the detoxification of many potential carcinogens and appear to play a critical role in the protection from the effects of carcinogens. The contribution of glutathione S-transferases M1 and T1 genotypes to susceptibility to the risk of gastric cancer and their interaction with cigarette smoking are still unclear. The aim of this study was to determine whether there was any relationship between genetic polymorphisms of GSTT1 and GSTT1 and gastric cancer. METHODS: A population based case-control study was carried out in a high-risk area, Changle County, Fujian Province, China. The epidemiological data were collected by a standard questionnaire and blood samples were obtained from 95 incidence gastric cancer cases and 94 healthy controls. A polymerase chain reaction method was used to detect the presence or absence of the GSTT1 and GSTT1 genes in genomic DNA. Logistic regression model was employed in the data analysis. RESULTS: An increase in risk for gastric cancer was found among carriers of GSTT1 null genotype. The adjusted odds ratio (OR) was 2.63 95% Confidence Interval (95% CI) 1.17-5.88, after controlling for age, gender, cigarette smoking, alcohol drinking, and fish sauce intake. The frequency of GSTT1 null genotype in cancer cases (43.16%) was not significantly different from that in controls (50.00%). However, the risk for gastric cancer in those with GSTT1 null and GSTT1 non-null genotype was significantly higher than in those with both GSTT1 and GSTT1 non-null genotype (OR = 2.77, 95% CI 1.15-6.77). Compared with those subjects who never smoked and had normal GSTT1 genotype, ORs were 1.60 (95% CI:0.62-4.19) for never smokers with GSTT1 null type, 2.33 (95% CI 0.88-6.28) for smokers with normal GSTT1, and 8.06 (95% CI 2.83-23.67) for smokers with GSTT1 null type. CONCLUSIONS: GSTT1 gene polymorphisms may be associated with genetic susceptibility of stomach cancer and may modulate tobacco-related carcinogenesis of gastric cancer.

Risk factors for the occurrence of insulinoma: a case-control study

BACKGROUND: The etiology of insulinoma is poorly understood. Few studies investigated the possible roles of environmental factors and lifestyle in the pathogenesis of insulinoma. The aim of this study is to identify risk factors associated with occurrence of insulinoma in the Chinese population. METHODS: This study consisted of 196 patients with insulinoma and 233 controls. Demographic information of the patients and controls and risk factors of the disease were analyzed. Univariate and unconditional multivariable logistic regression analyses were made to estimate odds ratios (ORs) and possible risk factors. RESULTS: Approximately 68.88% (135/196) of the patients were from rural areas in contrast to 10.30% (24/233) of the controls (P【0.0001). This difference was confirmed by the multivariate analysis (OR=4.950; 95% CI: 2.928-8.370). Family history of pancreatic endocrine tumor (OR=16.754; 95% CI: 2.125-132.057) and other cancers (OR=2.360; 95% CI: 1.052-5.291) was also related to a high-risk population of insulinoma. CONCLUSION: Rural residents or people who have a family history of pancreatic endocrine tumor and other cancers are a high-risk population of insulinoma.

Associations between coagulation factorⅫ,coagulation factorⅪ,and stability of venous thromboembolism:A case-control study

BACKGROUND Pulmonary embolism(PE)is a fatal clinical syndrome that is generally caused by an embolus from unstable deep venous thrombosis(DVT).However,clinical and biochemical factors that are related to the stability of DVT are not fully understood.AIM To evaluate the relationships between plasma antigen levels of factor XII(FXII:Ag)and factor XI(FXI:Ag)with the stability of DVT.METHODS Patients with DVT and no PE,DVT and PE,and controls with no DVT or PE that matched for age,gender,and comorbidities were included in this study.FXII:Ag and FXI:Ag in peripheral venous blood were measured using enzyme-linked immunosorbent assays.RESULTS Using the 95th percentile of FXI:Ag in patients with DVT and PE as the cut-off,a higher FXI:Ag was associated with a higher risk of unstable DVT(odds ratio:3.15,95%confidence interval:1.18-8.43,P=0.019).Stratified analyses showed consistent results in patients≤60 years(P=0.020),but not in those>60 years(P=0.346).CONCLUSION Higher plasma FXI:Ag might be a marker for unstable DVT,which might be associated with PE in these patients.