Maternal smoking and adverse birth outcomes among singletons and twins

OBJECTIVES: This study assessed the effects of maternal smoking on birth outcomes among singletons and twins. METHODS: An algorithm was developed to link twins with their siblings in the 1995 Perinatal Mortality Data Set. A random-effects logistic regression model was then used to estimate the association between maternal smoking and several adverse outcomes for a random sample of singletons and for all twins with available maternal smoking information. RESULTS: The algorithm successfully linked sibling pairs for 91% of the twin sample. Maternal smoking was associated with a significantly increased risk of low birthweight, very low birthweight, and gestation of less than 33 weeks for both singletons and twins and with an increased risk of gestation of less than 38 weeks, infant mortality, and placental abruption for singletons. Among smokers, negative impacts on the risk of low birthweight, very low birthweight, and extreme premature delivery were significantly higher for women carrying twins. CONCLUSIONS: Some of the negative effects of smoking on low birthweight and preterm delivery are greater for twins than for singletons. Women carrying twins should be warned that smoking increases their already high risk of serious infant health problems.     

The association between cholesterol cholelithiasis and coronary heart disease in Framingham, Massachusetts

A relationship between cholesterol gallstone disease and atherosclerosis or its sequellae has long been postulated but has never been adequately proven. Data for this investigation of the relationship of diagnosed cholesterol cholelithiasis to subsequent incident coronary heart disease were obtained from a review of the pre-existing prospectively collected medical records of the 5,209 individuals followed since 1952 as members of the original cohort of the Framingham Heart Study. Preliminary univariate examination of these data, making no correction for time ordering of the conditions or for shared risk factors, indicated a significant modest positive association in men but no relationship in women. Logistic multiple regression analyses, allowing for the effects of time ordering and for eight standard coronary disease risk factors, confirmed these findings. The authors speculate that the presence of cholesterol gallstones in male patients may be indicative of an unfavorable lipoprotein profile. These results have clinical implications in that male gallstone patients are at increased risk for subsequent coronary disease and should be monitored accordingly. This investigation marks the first time that a relationship between these conditions has been established using a longitudinal cohort study approach.     

Birthweight and perinatal mortality among singletons and twins in north-eastern Tanzania

BACKGROUND: Low birthweights as well as high perinatal mortality rates are common in most African populations. Little is known, however, about how low birthweight corresponds with higher mortality rates within African populations. Twins are known to have lower birthweights and higher perinatal mortality rates than singletons. If lower birthweights represent higher perinatal risk per se, small twins within a population with generally lower birthweights should have critically increased risks. METHODS: In total, 15,255 births in a Tanzanian hospital during 1999-2006 were analysed to determine birthweight distribution and examine perinatal mortality rates (including stillbirths and neonatal deaths within 24 hours) by birthweight in twins and singletons. Referral births from outside the district where the hospital was situated were excluded from analysis. RESULTS: The mean birthweight for births within an estimated normal distribution was 3172 g, with a standard deviation of 462 g. The overall perinatal mortality rate was 43.9 per 1000 births (95% confidence interval: 40.7-47.2). Perinatal mortality rates among twins and singletons were 91.0 and 41.1 per 1000 babies respectively, corresponding to a relative risk of 2.2 (95% confidence interval: 1.7-2.8). The birthweight distribution for twins was shifted to lower birthweights. Twins had a generally lower birthweight and an excess of extremely small births as compared to singletons. The increased mortality rate for twins appeared to be independent of birthweight. CONCLUSIONS: The two-fold increased risk of perinatal death for twins was observed across the whole birthweight distribution, and very small twins appeared to have an excess perinatal risk that was almost similar to that of larger twins.     

Migration and coronary heart disease: A study of Finnish twins living in Sweden and their co-twins residing in Finland

BACKGROUND: Finland and Sweden are neighbouring countries with a substantially higher incidence and mortality from coronary heart disease (CHD) in Finland. Migration from Finland to Sweden has resulted in a population of about 187,000 Finnish immigrants, with a higher risk of CHD than Swedes. The aim of the present study was to analyse the prevalence of CHD in migrants to Sweden compared with co-twins remaining in Finland. METHODS: The study population consisted of twin pairs of the Finnish Twin Cohort Study where at least one twin had lived one year or more in Sweden, including 1,534 subjects and 251 complete twin pairs discordant regarding residency in Sweden. Emigrant twins were compared with nonmigrant co-twins regarding prevalence of CHD in 1998. CHD prevalence was assessed by self-reported questionnaires validated using information from a clinical examination. RESULTS: Self-reported CHD showed a good correspondence with clinical diagnosis. Differences in social and behavioural risk factors for CHD among men were small but emigrants were more physically active than non-migrants. Female emigrants had less overweight and better education, but were more often working class than non-migrants. Intra-pair comparisons restricted to migration discordant pairs showed a tendency towards a reduced prevalence of CHD in the migrant co-twins (0.6; 0.3-1.4). In analyses of all subjects disregarding pair status, emigrants showed a reduced prevalence of CHD compared with subjects always living in Finland (0.6; 0.4-0.9). CONCLUSION: Emigration from Finland to Sweden may be associated with a reduced prevalence of CHD. The causes are most likely multifactorial and may involve changes in dietary habits, physical activity, psychosocial factors, and inflammation.     

A comparison of recent trends in infant mortality among twins and singletons

Overall infant mortality rates have steadily declined in recent years. The goal of this study was to examine whether recent declines in infant mortality were similar for twins and singletons, and to assess the impact of differing birthweight distributions on these relationships. Linked birth and infant death records for 1985-86 and 1995-96 were used to calculate infant mortality rates for twins and singletons for the two time periods. Bootstrap simulations were used to estimate rates of decrease between the two time periods and to determine whether these rates differed between twins and singletons. Between 1985-86 and 1995-96, infant mortality among twins declined significantly faster than among singletons (36% vs. 29%, P < 0.05). This difference was true for both black and white infants (black: 28% for twins vs. 22% for singletons; white: 38% for twins vs. 31% for singletons). Within birthweight categories, infant mortality declined more rapidly among twins than among singletons, although differences were not always significant. Factors and circumstances that contributed to the infant mortality decline in the United States have benefited twins to a greater extent than singletons.     

中性粒细胞外陷阱与冠心病急性心肌梗死关联的临床流行病学研究

目的  探讨冠状动脉粥样硬化性心脏病(coronary atherosclerotic heart disease, CAHD)急性心肌梗死(acute myocardial infarction, AMI)发作及冠脉旁路移植术(coronary artery bypass graft, CABG)后周围血中性粒细胞胞外陷阱(neutrophil extracellular traps, NETs)水平变化及作用,为有效防控CAHD及AMI提供新依据。 方法  选择AMI患者和健康对照(healthy control, HC)各52例,ELISA法检测AMI发病时治疗前(pre-treatment, PRT)组及手术治疗后(post-operative treatment, POT)组周围血NETs、B因子活化片段a(fragment a of the factor B, Ba)、补体片段5a(fragment a of the 5th complement, C5a)及髓过氧化酶(myeloperoxidase, MPO)水平,检测结果的组间比较采用t检验,PRT组内观察指标间的相关性分析采用Pearson相关分析。 结果  PRT组和POT组各检测指标均高于HC组,PRT组心肌肌钙蛋白I(cardiac troponin I, cTnI)、NETs、Ba、C5a和MPO高于POT组[分别为(0.279±0.132)ng/ml vs.(0.016±0.008)ng/ml, P < 0.001;(0.466±0.143)OD值vs.(0.378±0.151)OD值, P=0.002;(72.812±30.144)pg/ml vs.(60.491±28.323)pg/ml, P=0.001;(327.112±203.228)ng/ml vs.(260.411±135.984)ng/ml, P=0.025;(75.782±33.596)ng/ml vs.(58.462±29.647)ng/ml, P=0.008];PRT组中NETs分别与Ba、C5a及MPO呈正相关(分别为r=0.394, P=0.001;r=0.324, P=0.030和r=0.406, P < 0.001),且Ba与C5a呈正相关(r=0.436, P < 0.001),但cTnI仅与NETs呈正相关(r=0.352, P=0.008)。POT组中,cTnI虽已恢复正常值范围,但仍高于HC组cTnI [(0.016±0.008)pg/ml vs.(0.012±0.007)pg/ml, P=0.016]。 结论  CAHD患者在AMI发作期和接受CABG手术后,持续存在高水平NETs及与其相关的高补体旁路活化状态,有助于病情进展和心肌梗死再发,干预NETs形成可能是防治CHAD进展和AMI发生的潜在途径之一。     

The influence of prevalent cohort bias in the association between periodontal disease progression and incident coronary heart disease

PurposeIn longitudinal studies, the onset of the index condition (e.g. exposure) does not always coincide with the start of a study's observation period, leading to the possibility of bias in estimation that derives from studying prevalent exposure rather than new exposure. We investigate the possible role of this bias in the relationship between periodontitis progression and coronary heart disease (CHD) among a cohort of men participating in the Veterans Administration Dental Longitudinal Study.MethodsAt baseline, there were 298 men with existing (i.e., prevalent) periodontitis. During follow-up, routine dental inspection identified 163 new (i.e., incident) cases of periodontitis. Change in mean alveolar bone loss score (MBLS) served as the measure of disease progression. Tabular analyses were performed to obtain crude, stratified, and adjusted measures of the association for periodontitis cases overall and separately for prevalent and incident cases. Potential bias was evaluated by comparing estimates across these subcohorts.ResultsAmong all periodontitis cases, increasing MBLS was associated with increasing risk of CHD event. Subdividing periodontal cases into new and prevalent cases revealed that the relationship was most pronounced among incident periodontitis cases (incident rate ratio for MBLS change >0.5 = 5.4), compared with prevalent cases (incident rate ratio for MBLS change >0.5 = 2.5).ConclusionsStudying prevalent cases of periodontitis underestimates the association between incidence periodontitis and CHD.     

非酒精性脂肪肝与冠心病和脑血管病关系的研究

目的非酒精性脂肪肝与冠心病和脑血管病关系的研究。方法基于非酒精性脂肪肝患者冠心病和脑血管病的发病风险增高这一假设，我们对我院6年间的住院病历进行了回顾性研究，对年龄和性别匹配的550例非酒精性脂肪肝患者和550例正常肝脏患者的临床资料加以对比分析。结果非酒精性脂肪肝患者的收缩压、舒张压以及体重指数均显著高于正常肝脏者，非酒精性脂肪肝患者的ALT水平较之于正常肝脏者明显增高。非酒精性脂肪肝患者中冠心病发病率为36．5％，脑血管病发病率为25．6％；正常肝脏中冠心病发病率为12．2％，脑血管病发病率为7．1％。结论非酒精性脂肪肝患者的冠心病发病率和脑血管病发病率均显著增高。     

Adult socioeconomic position and the association between height and coronary heart disease mortality: findings from 33 years of follow-up in the Whitehall Study

In the Whitehall Study, which followed 17,139 male civil servants over 33 years, the association between tall stature and coronary heart disease (CHD) mortality differed between employment grades. In men without CHD at study entry, the hazard ratio per 15-cm increase in height was 0.77 (95% confidence interval [CI]=0.69, 0.85; P<0.001) for the highest grades, but 0.84 (95% CI=0.69, 1.03; P=.10) for middle and 0.95 (95% CI=0.75, 1.20; P=.65) for low grades, suggesting that childhood and adult social conditions may interact in their influence on coronary risk.     

The association between leisure time physical activity and coronary heart disease among men with different physical work demands: a prospective cohort study

The interplay of occupational and leisure time physical activity (LTPA) in affecting cardiovascular health is subject to debate. This study aimed to examine the independent and interacting associations of leisure time and occupational physical activity (OPA) with the incidence of coronary events within the BELSTRESS cohort. The study included 14,337 middle-aged men free from coronary heart disease at baseline. Standardized questionnaires and clinical examinations were used to assess socio-demographic factors, level of physical activity, job strain and classical coronary risk factors. The incidence of clinical coronary events was monitored during a mean follow-up time of 3.15 years. Results demonstrated overall a beneficial relation of LTPA and an adverse relation of physical work demands with cardiovascular health. However, an interaction effect between both physical activity types was observed, showing that men with high physical job demands who also engaged in physical activity during leisure time had an almost four times increased incidence of coronary events after adjusting for socio-demographic and classical coronary risk factors (HR 3.82; 95 % CI 1.41–10.36). Stratified analyses revealed that moderate to high physical activity during leisure time was associated with a 60 % reduced incidence rate of coronary events in men with low OPA (age adjusted HR 0.40; 95 % CI 0.21–0.76), while this protective association was not observed in workers being exposed to high physical work demands (age adjusted HR 1.67; 95 % CI 0.63–4.48). These findings suggest that recommendations regarding LTPA should be tailored according to the level of occupational physical activity.     

Association between height and coronary heart disease mortality: a prospective study of 35,000 twin pairs

An inverse association between height and risk of coronary heart disease (CHD) is well demonstrated, but it is not known whether this association is because of genetic factors, socioeconomic background, or other environmental factors. Four population-based twin cohorts with register-based follow-up data on CHD mortality from Denmark (1966-1996), Finland (1975-2001), and Sweden (1963-2001 and 1972-2001) were used to investigate this question; response rates varied between 65% and 86%. Together, the cohorts included 74,704 twin individuals (35,042 complete twin pairs) with 5,943 CHD deaths during 1.99 million person-years of follow-up. Cox and conditional logistic regression models were used. Per 1-standard deviation decrease in height, height was inversely associated with CHD mortality in men (hazard ratio = 1.08, 95% confidence interval (CI): 1.04, 1.12) and in women (hazard ratio = 1.06, 95% CI: 1.01, 1.10). A twin who had died from CHD was on average shorter than the co-twin within monozygotic pairs (odds ratio = 1.27, 95% CI: 1.12, 1.44, with no sex difference), whereas a weaker association was found within dizygotic pairs in men (odds ratio = 1.01, 95% CI: 0.91, 1.13) and in women (odds ratio = 1.14, 95% CI: 1.01, 1.28). The inverse association between height and CHD mortality found within monozygotic discordant twin pairs suggests that this association is because of environmental factors that directly affect height and CHD risk.     

Comparison of infant mortality among twins and singletons: United States 1960 and 1983

Infant mortality among US black and white twins and singletons was compared for 1960 and 1983 using the Linked Birth/Infant Death Data Sets from the National Center for Health Statistics. Both twin and singleton infant mortality rates showed impressive declines since 1960 but almost all of the improvement in survival for both twins and singletons was related to increased birth weight-specific survival rather than improved birth weight distribution. One-half of white twins and two-thirds of black twins weighed less than 2,500 g at birth, and 9% of white twin births and 16% of black twin births were in the very low (less than 1,500g) birth weight category. In 1983, twin infant mortality rates were still four to five times that of singletons. However, twins had a survival advantage in the 1,250-3,000 g range, which persisted after adjustment for gestational age. Cause-specific mortality among twins was considerably higher for every major cause of death: twin mortality risks due to newborn respiratory disease, maternal causes, neonatal hemorrhage, and short gestation/low birth weight were six to 15 times that of singletons. The lowest twin-to-singleton mortality ratios observed were for congenital anomalies and sudden infant death syndrome with relative risks twice that of singletons. The data underscore the need to develop effective strategies to decrease infant mortality among twins.     

Smoking among Finnish pulp and paper workers--evaluation of its confounding effect on lung cancer and coronary heart disease rates

The possible confounding caused by smoking was studied in connection with a mortality and cancer incidence study of 3,520 workers in the pulp and paper industry. A group 1,290 sawmill workers was used for comparison in addition to the expected numbers based on national statistics. A total of 801 questionnaires was sent to a representative sample of the workers, 537 to people still alive and 264 to the next-of-kin of decedents. The reply percentage was 86.6 for the former and 80.9 for the latter. The prevalence of smoking was determined for 1956 and 1981. The proportions of moderate and heavy smokers were assessed for 1981, and smoking indices were calculated for each occupational group. The estimated rate ratios for lung cancer in relation to smoking categories and the corresponding smoking-adjusted standardized incidence ratios were calculated for 1981, and they were compared with the observed standardized incidence ratios for lung cancer. The smoking habits could not explain the observed excess of lung cancer, nor the increased mortality from coronary heart disease found among the pulp and paper workers. Postal questionnaires may be a feasible tool for assessing smoking habits in retrospective cohort studies.     

探究中国双生子人群中的冠心病遗传-生活方式交互作用

目的:分析中国成年双生子人群的冠心病遗传-生活方式交互作用。方法:利用中国双生子登记系统募集的研究对象,构建单变量交互作用模型,通过分析生活方式对冠心病遗传效应的效应修饰作用,探索冠心病的遗传-生活方式交互作用。结果:本研究共纳入20 477对≥25岁的同性别双生子,含395例冠心病患者,其中66对双生子均患冠心病。调...