Dietary intake and serum levels of copper and zinc and risk of hepatocellular carcinoma:A matched case-control study

Background:Copper and zinc are involved in the development of multiple malignancies;yet,epidemiological evidence on hepatocellular carcinoma(HCC)is limited.This study aimed to investigate the association between dietary intake and serum levels of copper and zinc with the risk of HCC.Methods:A total of 434 case-control pairs matched for sex and age(±1 year)were included in this study.Cases with newly diagnosed HCC were from the Guangdong Liver Cancer Cohort(GLCC)study,and healthy controls were from the Guangzhou Nutrition and Health Study(GNHS).A semi-quantitative 79-item food frequency questionnaire(FFQ)was used to assess habitual dietary intakes of copper and zinc.Serum levels of copper and zinc were measured by using inductively coupled plasma mass spectrometry.The copper(Cu)/zinc(Zn)ratio was computed by dividing copper levels by zinc levels.Conditional logistic regression models were performed to calculate the odds ratio(OR)and 95%confidence intervals(CI)for per 1 standard deviation increase(per-SD increase)in copper and zinc levels.Results:Higher dietary intake(OR_(per-SD increase)=0.65,95%CI:0.44,0.96,P_(trend)=0.029)and serum levels of zinc(OR_(per-SD increase)=0.11,95%CI:0.04,0.30,P_(trend)<0.001)were both associated with a lower risk of HCC.Subgroup analyses showed that the inverse association was only pronounced in men but not in women(P_(interaction)=0.041 for dietary zinc intake and 0.010 for serum zinc levels).Serum copper levels(OR_(per-SD increase)=2.05,95%CI:1.39,3.03,P_(trend)=0.020)and serum Cu/Zn ratio(OR_(per-SD increase)=6.53,95%CI:2.52,16.92,P_(trend)<0.001)were positively associated with HCC risk,while dietary copper intake and dietary Cu/Zn ratio were not associated with HCC risk.Conclusion:Zinc may be a protective factor for HCC,especially among men,but the effects of copper on HCC risk are not clear.

Serum Microcystin-LR Levels Linked with Risk of Inflammatory Bowel Disease:A Matched Case-Control Study in China

Microcystin-LR(MC-LR),the most prevalent and diverse cyanotoxin produced by harmful cyanobacterial blooms,has been linked to gastrointestinal toxicity.Therefore,we conducted a case-control study across four regions in China to investigate this relationship.Inflammatory bowel disease(IBD)cases(219)were matched with healthy controls(438)based on age and gender and conditional logistic regression models and Restricted cubic splines were used to evaluate the association between MC-LR exposure and IBD risk.We used quantitative real-time polymerase chain reaction to measure the expression levels of inflammatory factors.The levels of protein expression in the colorectum were determined using Western blotting(WB).Compared to the lowest quartile of serum MC-LR levels,the adjusted odds ratios and 95%confidence intervals(CI)for the highest quartiles of serum MC-LR levels were 5.51(2.70,11.21).The RCS was shown the association between serum MC-LR levels and IBD risk was nonlinear(Pnonlinear<0.001).In the animal experiments,MC-LR resulted in colorectal injury via the PI3K/AKT signaling pathway.Our study provides the evidence that serum MC-LR exposure is significantly associated with the risk of IBD in China.Animal study results indicate that MC-LR probably causes IBD via the PI3K/AKT signaling pathway.

Evaluation of live attenuated S79 mumps vaccine effectiveness in mumps outbreaks： a matched case-control study

Background Mumps virus infection is a potentially serious viral infection of childhood and early adulthood. In China, live attenuated S79 mumps vaccine has been licensed for pediatric use since 1990. The objective of this study was to determine the effectiveness of live attenuated S79 mumps vaccine against clinical mumps in outbreaks. Methods Cases were selected from mumps outbreaks in schools in Guangzhou between 2004 and 2005. Each case was matched by gender, age and classroom. Vaccination information was obtained from Children＇s EPI Administrative Computerized System. Vaccine effectiveness （VE） was calculated for 1 or 2 doses of S79 vaccine with 95% confidence intervals （CI）. Results One hundred and ninety-four cases and 194 controls were enrolled into the study. VE of the S79 mumps vaccine for 1 dose versus 0 confer protection 80.4% （95% Cl, 60.0%-90.4%） and VEs against mumps in outbreaks for 1 dose of mumps vaccine are similar among those children aged 4-9 years and aged over 10 years old. Conclusion The live attenuated S79 mumps vaccine can be effective in preventing clinical mumps outbreaks.

Having a Partner and Having Children:Comparisons of Adults with Congenital Heart Disease and the General Population:A 15-Year Case-Control Study

Objectives:To examine whether patients with congenital heart disease(CHD)are less likely to have a partner or children than individuals from the general population.Methods:Longitudinal study with two assessments of the same patients(n=244)from a hospital population and controls(n=238)from the German Socio-Economic Panel(GSOEP)using parental education,patients age,and sex as matching criteria.The first patient study was conducted between 5/2003 and 6/2004,the second one between 5/2017 and 4/2019.Controls were drawn from GSOEP-surveys 2004 and 2018.CHD-severity was classified according to type of surgery:curative,reparative,or palliative.Living single was used as outcome measure,for offspring the outcome was having children or not.Results:Among women with CHD the rate of those living single was higher than among controls with the differences depending on disease complexity(curative:OR=5.5;reparative:OR=1.9;palliative:OR=2.7).No statistically significant differences between patients and controls emerged in the male study population.With respect to children a marked difference emerged between women with CHD and controls.Among patients the odds of having children were lower than among controls(curative:OR=0.3;reparative:OR=0.3;palliative:OR=0.2).The rate of patients with children with CHD(women:5.6%;men:4.9%)was higher than expected(1%)if compared with the general population.Conclusions:Using partnership and children as outcome criteria,patients with CHD are disadvantaged if compared to subjects from the general population.In female patients the social consequences of the disease turned out as more pervasive than in women.

A Nested Case-Control Study to Explore the Association between Immunoglobulin G N-glycans and Ischemic Stroke

Objective This study prospectively investigates the association between immunoglobulin G(IgG)N-glycan traits and ischemic stroke(IS) risk.Methods A nested case-control study was conducted in the China suboptimal health cohort study,which recruited 4,313 individuals in 2013–2014. Cases were identified as patients diagnosed with IS, and controls were 1:1 matched by age and sex with cases. Ig G N-glycans in baseline plasma samples were analyzed.Results A total of 99 IS cases and 99 controls were included, and 24 directly measured glycan peaks(GPs) were separated from Ig G N-glycans. In directly measured GPs, GP4, GP9, GP21, GP22, GP23, and GP24 were associated with the risk of IS in men after adjusting for age, waist and hip circumference,obesity, diabetes, hypertension, and dyslipidemia. Derived glycan traits representing decreased galactosylation and sialylation were associated with IS in men(FBG2S2/(FBG2 + FBG2S1 + FBG2S2): odds ratio(OR) = 0.92, 95% confidence interval(CI): 0.87–0.97;G1n: OR = 0.74, 95% CI: 0.63–0.87;G0n: OR =1.12, 95% CI: 1.03–1.22). However, these associations were not found among women.Conclusion This study validated that altered Ig G N-glycan traits were associated with incident IS in men, suggesting that sex discrepancies might exist in these associations.

Reduced risk of dementia in patients with type 2 diabetes mellitus using Chinese herbal medicine:A nested case-control study

BACKGROUND Dementia is a prevalent condition in type 2 diabetes mellitus(T2DM)patients.While Chinese herbal medicine(CHM)is often employed as complementary therapy for glycemic control,its effect in controlling likelihood of dementia has not yet been fully elucidated.AIM To compare the risk of dementia between T2DM patients with and without CHM treatment.METHODS We undertook a nested case-control study and obtained data on patients 20-70 years of age who received medical care for T2DM between 2001 and 2010 from the National Health Insurance Research database in Taiwan.Cases,defined as those with dementia that occurred at least one year after the diagnosis of T2DM,were randomly matched to controls without dementia from the study cohort at a 1:1 ratio.We applied conditional logistic regression to explore the associations between CHM treatment and dementia.RESULTS A total of 11699 dementia cases were matched to 11699 non-dementia controls.We found that adding CHM to conventional care was related to a lower risk of dementia[adjusted odds ratio(OR)=0.51],and high-intensity CHM treatment was associated with an adjusted OR of 0.22.CONCLUSION This study shows that the cumulative CHM exposure was inversely associated with dementia risk in an exposureresponse manner,implying that CHM treatment may be embraced as a disease management approach for diabetic patients to prevent dementia.

Rural implementation of the perioperative surgical home:A case-control study

BACKGROUND Perioperative surgical home(PSH)is a novel patient-centric surgical system developed by American Society of Anesthesiologist to improve outcomes and patient satisfaction.PSH has proven success in large urban health centers by reducing surgery cancellation,operating room time,length of stay(LOS),and readmission rates.Yet,only limited studies have assessed the impact of PSH on surgical outcomes in rural areas.AIM To evaluate the newly implemented PSH system at a community hospital by comparing the surgical outcomes using a longitudinal case-control study.METHODS The research study was conducted at an 83-bed,licensed level-III trauma rural community hospital.A total of 3096 TJR procedures were collected retrospectively between January 2016 and December 2021 and were categorized as PSH and non-PSH cohorts(n=2305).To evaluate the importance of PSH in the rural surgical system,a case-control study was performed to compare TJR surgical outcomes(LOS,discharge disposition,and 90-d readmission)of the PSH cohort against two control cohorts[Control-1 PSH(C1-PSH)(n=1413)and Control-2 PSH(C2-PSH)(n=892)].Statistical tests including Chi-square test or Fischer’s exact test were performed for categorical variables and Mann-Whitney test or Student’s t-test were performed for continuous variables.The general linear models(Poisson regression and binomial logistic regression)were performed to fit adjusted models.RESULTS The LOS was significantly shorter in PSH cohort compared to two control cohorts(median PSH=34 h,C1-PSH=53 h,C2-PSH=35 h)(P value<0.05).Similarly,the PSH cohort had lower percentages of discharges to other facilities(PSH=3.5%,C1-PSH=15.5%,C2-PSH=6.7%)(P value<0.05).There was no statistical difference observed in 90-d readmission between control and PSH cohorts.However,the PSH implementation reduced the 90-d readmission percentage(PSH=4.7%,C1-PSH=6.1%,C2-PSH=3.6%)lower than the national average 30-d readmission percentage which is 5.5%.The PSH system was effectively established at the rural community hospital with the help of team-based coordinated multi-disciplinary clinicians or physician comanagement.The elements of PSH including preoperative assessment,patient education and optimization,and longitudinal digital engagement were vital for improving the TJR surgical outcomes at the community hospital.CONCLUSION Implementation of the PSH system in a rural community hospital reduced LOS,increased directto-home discharge,and reduced 90-d readmission percentages.

Interaction and Its Solution in Individual Matching Case-control Study

Objective To indicate the deficiency of the classical method for analyzing data on individual matching case-control study in consideration of the interaction between the study factor (exposure) and the matching factor, and to find out a proper method for handling this deficiency. Method First, experimental data with 50 pairs of cases and controls were used for strata analysis according to the values of a matching factor to illustrate the possible interaction between a risk factor (exposure) and the matching factor. Second, a detailed procedure was proposed for analyzing such data. Results Interaction between the study factor and matching factor was demonstrated by using strata analysis and unconditional logistic regression analysis. Therefore the results from the classical analysis for such data might be incorrect. Conclusion Data from individual matching case-control study design should be dealt with strata analysis or multivariate analysis to explore and evaluate the possible interaction between the s

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.

Cumulative logit model in the analysis of endometrial cancer under a matched pair case-control design

Background: Binary as well as polytomous logistic models are widely used for estimating odds ratios when the exposure of prime interest assumes unordered multiple levels under matched pairs case-control design. In our previous studies, we have shown that the use of a polytomous logistic model for estimating cumulative odds ratios when the outcome (response) variable is ordinal (in addition to being polytomous) under matched pairs case-control design. The cumulative odds ratios were estimated based on separate fitting of the model at each of the cutpoint level as compared to less than equal to that level. In this paper we propose an alternative method of estimating the cumulative odds ratios and reanalyze the Los Angeles Endometrial Cancer data in the context of dose levels of conjugated oestrogen exposure and development of endometrial cancer under the matched pair case-control design. Methods: In the present study, the cumulative logit model is fitted using a single multinomial logit model for the data. For this, the full maximum likelihood estimation procedure is adopted. A test for equality of the cumulative odds ratios across the exposure levels is proposed. Results: The analysis revealed that there is a strong evidence of risk for developing endometrial cancer due to oestrogen exposure above each of the three dose level as compared to less than equal to that level. The estimated values at the three cutpoint levels were found to be 6.17, 3.60 and 5.16 respectively. Conclusions: The odds of developing endometrial cancer are very high for the users of any amount of oestrogen, even if it is the least dose, as compared to the non-users.

Case-matched comparison of laparoscopy-assisted and open distal gastrectomy for gastric cancer

AIM: To compare shortand long-term outcomes of laparoscopy-assisted and open distal gastrectomy for gastric cancer. METHODS: A retrospective study was performed by comparing the outcomes of 54 patients who underwent laparoscopy-assisted distal gastrectomy (LADG) with those of 54 patients who underwent open distal gastrectomy (ODG) between October 2004 and October 2007. The patients' demographic data (age and gender), date of surgery, extent of lymphadenectomy, and differentiation and tumor-node-metastasis stage of the tumor were examined. The operative time, intraoperative blood loss, postoperative recovery, complications, pathological findings, and follow-up data were compared between the two groups.RESULTS: The mean operative time was significantly longer in the LADG group than in the ODG group (259.3 ± 46.2 min vs 199.8 ± 40.85 min; P < 0.05), whereas intraoperative blood loss and postoperative complications were significantly lower (160.2 ± 85.9 mL vs 257.8 ± 151.0 mL; 13.0% vs 24.1%, respectively, P < 0.05). In addition, the time to first flatus, time to initiate oral intake, and postoperative hospital stay were significantly shorter in the LADG group than in the ODG group (3.9 ± 1.4 d vs 4.4 ± 1.5 d; 4.6 ± 1.2 d vs 5.6 ± 2.1 d; and 9.5 ± 2.7 d vs 11.1 ± 4.1 d, respectively; P < 0.05). There was no significant difference between the LADG group and ODG group with regard to the number of harvested lymph nodes. The median followup was 60 mo (range, 5-97 mo). The 1-, 3-, and 5-year disease-free survival rates were 94.3%, 90.2%, and 76.7%, respectively, in the LADG group and 89.5%, 84.7%, and 82.3%, respectively, in the ODG group. The 1-, 3-, and 5-year overall survival rates were 98.0%, 91.9%, and 81.1%, respectively, in the LADG group and 91.5%, 86.9%, and 82.1%, respectively, in the ODG group. There was no significant difference between the two groups with regard to the survival rate. CONCLUSION: LADG is suitable and minimally invasive for treating distal gastric cancer and can achieve similar long-term results to ODG.

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.

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.

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.

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.