In this article, we presented the rationale and calculation procedures of the propcnsity score matching (PSM), and its application in the designing stage of an cpidcrniological study. Based on existing observational data, PSM can be used to select one or more comparable controls for each subject in 'treatment' group according to the propensity scores estimated by 'treatment' variable and main covariates. The results of an example analysis showed that the bias for main confounders between the treated and control samples declined more than 55% after PMS. Conclusion: PSM can reduce most of the confounding bias of the observational study, and can obtain approximate study effect to the randomized controlled trials when used in the designing of thc cpidcmiological study.

OBJECTIVETo study the relationship between estrogen receptor beta gene (ER beta) polymorphism and unknown aetiology hypomenorrhea in Southwestern China .

METHODSOne hundred eumenorrhea women were chosen as control group and another 100 hypomenorrhea patients as case group from Southwestern China. Restriction fragment length polymorphism (RFLP) of the Rsa I and Alu I in ER beta gene was analysed. The ER beta gene polymorphism genotype distribution in case group and control group was compared.

RESULTSR allele frequency in case and control groups was 37.5% and 48.5% respectively, the OR was 0.64 (95%CI: 0.42-0.97), P= 0.026. A allele frequency in case and control groups was 18.0% and 11.5% respectively, the OR was 1.69 (95%CI: 0.93-3.09), P= 0.07. RFLP of Rsa I and Alu I in both groups were distributed with polymorphism.

CONCLUSIONERbeta gene polymorphism has a relation with unknown aetiological hypomenorrhea. R allele may be the guard factor, and A allele may be its risk factor.

Adult ; Binding Sites ; genetics ; Deoxyribonucleases, Type II Site-Specific ; metabolism ; Estrogen Receptor beta ; genetics ; Female ; Gene Frequency ; Genetic Predisposition to Disease ; genetics ; Genotype ; Humans ; Menstruation Disturbances ; etiology ; genetics ; Polymerase Chain Reaction ; Polymorphism, Genetic ; genetics ; Polymorphism, Restriction Fragment Length ; Young Adult

OBJECTIVETo compare plasma and red blood cell folate levels among women in their first trimester of pregnancy from rural areas with high or low prevalence of neural tube defects.

METHODSA cross-sectional study was performed, among women in their first trimester of pregnancy from rural areas with high or low prevalence of neural tube defects in 2003. Non-fasting blood sample were collected and analyzed for plasma and red blood cell folate concentrations for 688 women.

RESULTSThe median plasma (10.53 nmol/L) and red blood cell folate (389.2 nmol/L) among women from the high prevalence rural area were lower than those of women from the low prevalence rural area (plasma folate: 30.39 nmol/L, red blood cell level folate: 926.0 nmol/L). Among women from the high prevalence area, about 50% and 43% were respectively, deficient for plasma and red blood cell folate, compared with 6% and 4% respectively, for women from the low prevalence area. The median plasma folate levels among women who took periconceptional folic acid supplements in both high and low prevalence areas were about twice higher than those who did not take the folic acid. The median red blood cell folate level of the folic acid users was 40% higher than those of the non-users. Among those who took folic acid, women in the low prevalence area had 70%-90% higher plasma folate concentration and twice higher red cell folate concentration than women in the high prevalence area.

CONCLUSIONWomen from the rural area with a high prevalence of neural tube defects had low plasma and red blood cell folate levels. Periconceptional supplementation with folic acid could substantially improve folate status of reproductive-aged women. However, supplementation with 0.4 mg of folic acid per day might be inadequate for women in the high prevalence rural area.

Dietary Supplements ; Erythrocytes ; chemistry ; Female ; Folic Acid ; administration & dosage ; blood ; Humans ; Neural Tube Defects ; epidemiology ; prevention & control ; Preconception Care ; Pregnancy ; Pregnancy Trimester, First ; Prevalence ; Rural Health

OBJECTIVEDietary factors that could potentially be related to the risk of birth defects are still unknown in Shanxi province, a region with high prevalence of neural tube defects(NTDs) in China. The main aim of this study was to evaluate the association between NTDs and local dietary factors.

METHODSA population-based case-control study was conducted during 2003-2005 in four selected counties of Shanxi province with 363 NTDs cases ascertained and 523 control babies without any external birth defects.

RESULTSBy multivariate logistic regression analysis, we found the NTDs risk was significantly associated with low consumption of meat and legume, high consumption of pickled vegetables, noncentralized supply of drinking water and drinking tea after adjusting for maternal education level and birth defects history. A significant dose response trend was found between the NTDs risk and the lower frequencies of meat and legume consumption and higher frequency of pickled vegetable consumption, with population attributable risks (PAR) of 69.4%, 22.0% and 18.5%, respectively. Mothers who got their drinking water from river or pond during periconceptional period were more likely to have a NTD-affected pregnancy [OR = 3.42, 95% CI: 1.44-8.09, population attributable risk (PAR) = 4.7%] compared with those who utilized tap or well water. Those who drank tea everyday had an elevated risk of having a NTD-affected pregnancy compared with those who didn't (OR = 4.65, 95% CI: 1.41-15.36, PAR = 2.6%).

CONCLUSIONHigher intake of meat and legume protects a woman from having a NTD-affected pregnancy, and consumption of pickled vegetables, drinking water from river or pond and drinking tea everyday increase the risk of having such a pregnancy in the study population.

Case-Control Studies ; China ; epidemiology ; Diet ; Female ; Humans ; Meat ; Neural Tube Defects ; epidemiology ; Pregnancy ; Risk Factors ; Vegetables ; Water Supply

Objective To explore the relationship between maternal passive smoking during early pregnancy and the risk of neural tube defects (NTDs). Methods Data was derived from a populationbased case-control study on birth defects in Shanxi province. The study subjects included 515 NTDs defects cases (236 cases of anencephaly, 237 spina bifida and 42 encephalocele) ascertained during January 2003 and June 2007 in the study areas and 682 normal controls randomly selected in the same residence during the same period as cases. Results The risk of NTDs in their offspring was 1.84 (95 % CI : 1.39-2.44) for mothers with passive smoking history during peri-conceptional period. There was a marked dose-response relation between maternal passive smoking and the risk of NTDs in offspring. Compared to the women without passive smoking, the NTDs risk in offspring was 1.51 for women with occasional passive smoking and 2.44 for women with passive smoking for almost everyday during the peri-conceptional period.Conclusion Maternal passive smoking during peri-conceptional period increased the risk of NTDs in offspring.

Objective To study the mechanism and protection of ulinastatin on organ functions in patients with severe disease.Methods Sixty patients in the intensive care unit(ICU)from October 2005 to July 2007 were randomly divided into a control group and an ulinastatin treatment group(each 30 cases).The patients in the control group received the conventional therapy,and the cases in the other treatment group accepted ulinastatin and conventional therapy.According to the disease situations,ulinastatin was administered 200-400 kU once,2-4 times a day,sequentially for 5-7 days.On the day of admission and 3, 5,and 7 days after admission in ICU respectively,blood samples were obtained for measuring alanine aminotransferase(ALT),aspartate aminotransferase(AST),creatinine(Cr),blood urea nitrogen(BUN), activated partial thromboplastin time(APTT),fibrinogen(FIB)and oxygenation index(PaO_2/FiO_2); whether breathing machine or hematodialysis was used and the end results were recorded.Results The rate of usage of breathing machine(23.3%),the incidences of hepatosis(3.3%)and renal dysfunction(10.0%) and fatality(3.3%)in ulinastatin treatment group were obviously lower than those of the control group (63.3%,23.3%,46.7%,10.0%,P0.05).Only one patient received bematodialysis in control group.Conclusion Ulinastatin can protect liver,renal and lung functions markedly and lower the incidence of multiple organ dysfunction syndrome and mortality in patients with severe disease.

OBJECTIVETo evaluate the reliability of the birth defects surveillance system in four counties with high prevalence of birth defects (Pingding, Xiyang, Taigu and Zezhou counties) in Shanxi province, China.

METHODSOne township was selected from each county as study site. The health workers chosen from township or village level were trained to visit families on the outcomes of each pregnancy who gave birth during year 2003 in the study site. The number of births and cases collected in the study were compared with that from the surveillance system. The number of births reported by surveillance system in four counties was also compared with the data from the local government. The criteria of evaluation were: 1) number of the missing report of births should < or = 5%, 2) the number of missing report on major external birth defects cases should < or = 10%. Researchers from the Peking University were responsible for examining the quality of surveillance in some terminal units of surveillance system.

RESULTSThe numbers of births reported in the study and from the surveillance system for four-township were 1043 and 997, respectively. 46 births were missing and the rate of misreporting for births was 4.4%. The numbers of birth defects cases reported in the study and from the surveillance system were 30 and 29, respectively. 1 case of birth defect as missed, and rate of misreporting for birth defects cases was 3.3%. The total number of births reported from surveillance was similar to that in the study in four counties, with a difference of 1.2%. Birth registry data was rather readable and special health workers responsible for surveillance work were present in all the terminal units of the surveillance system.

CONCLUSIONThe misreporting of births and cases existed in the birth defects surveillance system of the four counties in Shanxi province, but were lower than the allowable criteria. The surveillance units had better registration, reporting and administration of births and birth defect cases. Hence, the quality of the data from the surveillance system in these four counties was reliable.

Birth Certificates ; China ; epidemiology ; Congenital Abnormalities ; epidemiology ; Female ; Humans ; Infant, Newborn ; Population Surveillance ; Pregnancy ; Pregnancy Outcome ; Registries ; Reproducibility of Results

BACKGROUNDMaternal exposure to nitrate, nitrite, and N-nitroso compounds from drinking water or diet has been associated with an increased risk of neural tube defects (NTDs) in some studies. Pickled vegetables contain relatively large amounts of nitrite and N-nitroso compounds. We examined the association between maternal periconceptional consumption of pickled vegetables and NTDs in Shanxi Province of northern China.

METHODSData were derived from a population based case-control study of major external birth defects in four counties of Shanxi Province. Participants included 519 NTDs cases identified between 2003 and 2007 and 694 healthy controls. Exposure information was collected within 1 week after delivery. Multivariable non-conditional Logistic regression model was used to estimate the adjusted odds ratio (OR) controlling for potential confounding variables.

RESULTSThe risk of NTDs was positively associated with the frequency of the consumption of pickled vegetables by the mother. Compared with pickled vegetables consumption at < 1 meal/week, the adjusted OR for consumption at 1 - 3, 4 - 6, and > 6 meals/week were 1.3 (95% confidence interval (CI): 1.0, 1.8), 1.9 (1.1, 3.2), and 3.6 (1.9, 6.9), respectively. A protective effect was found for maternal meat consumption at ≥ 1 meal/week (adjusted OR: 0.6, 95%CI: 0.4, 0.7) and egg or milk consumption at ≥ 1 meal/week (adjusted OR: 0.6, 95%CI: 0.4, 0.8).

CONCLUSIONMaternal periconceptional consumption of pickled vegetables may increase the risk for NTDs in Shanxi Province.

Adult ; Case-Control Studies ; Female ; Humans ; Infant, Newborn ; Logistic Models ; Maternal Exposure ; adverse effects ; Multivariate Analysis ; Neural Tube Defects ; etiology ; Nitrites ; adverse effects ; Nitroso Compounds ; adverse effects ; Pregnancy ; Risk Factors ; Vegetables ; adverse effects ; chemistry ; Young Adult

OBJECTIVETo study the distribution of serotype and the positive rate of toxins among vibrio cholerae non-O(1) isolated from environmental waters in Foshan city.

METHODSWater specimens were collected from river and cultured for vibrio cholerae non-O(1). The PCR method was used to detect cholerae enterotoxin (CT) gene; the ELISA method was used to detect heat-stable toxin (ST) and heat-labile toxin (LT).

RESULTS478 vibrio cholerae non-O(1) strains were isolated from 1 644 water specimens, with a positive rate of 29.07%. Serological assay showed that the main serotype of vibrio cholerae non-O(1) in Foshan city is VBO(7). Positive rate of CT, ST and LT were 1.91%, 13.14% and 12.17%, respectively.

CONCLUSIONSA few non-O(1) strains were found to have several virulent factors simultaneously, and the results suggest that vibrio cholerae non-O(1) in environmental waters is potentially pathogenic and may affect people's health. It is necessary to pay attention to the prevention of diarrhoea caused by vibrio cholerae.

China ; Enterotoxins ; genetics ; Environmental Monitoring ; methods ; Enzyme-Linked Immunosorbent Assay ; Polymerase Chain Reaction ; Seasons ; Serotyping ; Vibrio cholerae non-O1 ; classification ; genetics ; isolation & purification ; Water ; analysis ; Water Microbiology

Objective To examine the impact of pregnancy termination before 28 weeks of gestation on the overall prevalence of neural tube defects (NTDs).Methods Data collected during the period of 2004 and 2010 from a birth defects surveillance system in Pingding county and Talgu county of Shanxi province were used.Number of births ≥28 weeks of gestation and number of cases with major birth defects among the births were collected.Terminations of pregnancies before 28 weeks of gestation due to prenatal diagnosis were also collected.The total prevalence of neural tube defects,prevalence before 28 weeks of gestation,and prevalenee of ≥28 weeks gestation were calculated using the total number of pregnancies of ≥28 weeks of gestation as denominator.The prevalence data were compared to examine the impact of pregnancy termination on the total prevalence.The proportions of pregnancy terminations before 28 weeks of gestation due to prenatal diagnosis of an NTD against the total number of NTD cases were also calculated.Results During 2004-2010,52 366 births were recorded,and 485 NTD cases were ascertained.The overall prevalence of NTDs was 92.6 per 10 000 births,with prevalence of ＜28 weeks gestation due to pregnancy terminations as 60.9 per 10 000 births,while the prevalence of ≥28 weeks of gestation was 31.7 per 10 000 births.NTD prevalence of ≥28 weeks gestation was 66.0％ lower than the total NTD prevalence.In the last two years,the proportion of NTDs ascertained ≥28 weeks gestation accounted for about 40.0％ of the total NTD cases.Conclusion A birth-defect-surveillance program that covered only tregnancies ≥28 weeks of gestation resulted in a severe underestimation of the total birth prevalence of NTDs,especially for anencephaly.We would recommend that the current national birth defects surveillance system should include pregnancy terminations before 28 weeks of gestation and the calculation of total NTD prevalence should also include these cases into the numerator,so as to better estimate true population NTD prevalence,upon which the related public health policy is based.