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Biomedical subjects

D A Savitz

Publications and source records attributed to D A Savitz.

At least 181 records · Page 10Linked to original sources
PubMed1992

Preterm birth subtypes among blacks and whites.

The differences in preterm birth between blacks and whites are poorly understood. Our study examined subtypes of moderately preterm delivery (34-36 completed weeks of gestation) and very preterm delivery (20-33 weeks) in blacks and whites using North Carolina birth certificate data for 1988-1989. We divided the causes of preterm birth into three categories: preterm premature rupture of the membranes, indication of pregnancy complication, and idiopathic preterm deliveries. The overall prevalence of preterm birth was 8.0% and 16.7% for whites and blacks, respectively. The entire gestational age distribution of blacks was shifted to earlier ages relative to whites. More highly educated blacks still had higher risks of moderately and very preterm deliveries than less educated whites. Multivariate analysis, controlling for other factors, showed that blacks had 3.3, 2.5, and 3.5 times the risk of whites to have preterm premature rupture of the membranes, complication-related, and idiopathic delivery, respectively, among very preterm births, and 1.6, 1.9, and 2.0 times the risk of whites for moderately preterm births of the same three types.

Black People↗
PubMed1992

The effects of nondifferential confounder misclassification in ecologic studies.

In ecologic studies, covariate levels of groups are often quantified as the prevalence of a dichotomous covariate. We show that, under certain conditions, nondifferential misclassification of such a binary covariate does not reduce the ability to control confounding by the covariate in ecologic studies. Thus, any remaining exposure-disease association in an adjusted ecologic analysis cannot be ascribed to incomplete control for confounding due to nondifferential misclassification of the dichotomy under those conditions, although residual confounding by the underlying covariate may still be present. This point is illustrated by ecologic analyses of the association between population density and mortality from lung cancer in women in 30 administrative districts of the Federal Republic of Germany, in which control for cigarette smoking is required.

Confounding Factors, Epidemiologic↗
PubMed1992

Prenatal events and the risk of subependymal/intraventricular haemorrhage in very low birthweight neonates.

The effects of prenatal factors on the risk of subependymal and/or intraventricular brain haemorrhage in very low birthweight (VLBW) neonates were studied. Data were collected on 201 consecutively born VLBW neonates without major congenital anomalies, who were born at a regional obstetric referral centre. Brain haemorrhage was identified by cranial ultrasound examinations. The reliability of these examinations (concordance among readers' interpretations) was assessed and found to be moderate (kappa = 0.47 for the finding of subependymal haemorrhage (SEH); kappa = 0.50 for the finding of intraventricular haemorrhage (IVH)). Prenatal factors were more strongly associated with IVH than with SEH. In univariable analyses, maternal pre-eclampsia, multiple gestation and maternal treatment with betamethasone were associated most strongly with a decreased risk of haemorrhage whereas labour and vaginal delivery were associated most strongly with an increased risk. These associations remained in a multivariable analysis which included prenatal events (maternal illnesses, fetal presentation and obstetrical interventions), as well as gestational age, birthweight, gender, treatment with assisted ventilation, and the occurrence of pneumothorax. Further aetiological study of the effects of prenatal factors could provide information useful in preventing SEH/IVH.

Cerebral Hemorrhage↗
PubMed1992

Pregnancy-induced hypertension in North Carolina, 1988 and 1989.

INTRODUCTION: Pregnancy-induced hypertension (PIH) is a highly prevalent pregnancy complication with adverse effects on maternal and infant health. Epidemiologic research concerning its etiology is limited. METHODS: Birth records from North Carolina for the period 1988 through 1989 included an indication of the presence of PIH. The risk of PIH was examined in relation to several maternal characteristics and exposures, including reproductive history, demographic characteristics, and tobacco use during pregnancy. Risk ratio estimates, adjusted for confounders, were calculated contrasting PIH among exposed vs unexposed women. RESULTS: The overall risk of PIH was 43.1 per 1000 births, with multiple pregnancies, nulliparity, and advanced maternal age associated with markedly increased risks. Tobacco use was inversely associated with PIH, and Blacks and Whites were at virtually equal risk. CONCLUSIONS: Problems in diagnosis and classification impede research in this area, with birth certificates limited in quality and breadth of information. Nonetheless, several patterns emerged that are worthy of further epidemiologic evaluation using more sophisticated designs.

Adult↗
PubMed1991

Prenatal exposure to parents' smoking and childhood cancer.

The relation between parents' tobacco smoking prior to birth and cancer in the offspring was investigated with the use of data from a case-control study. Incident cases included all children (aged 0-14 years) diagnosed in Denver, Colorado from 1976 to 1983. Controls were selected through random digit dialing, and matched to cases on age, sex, and geographic area. Information on smoking by parents and other household members was obtained by personal interview for 223 cases and 196 controls. After adjustment for father's education, mother's smoking during the first trimester of pregnancy was associated with an increased risk for all cancers combined (odds ratio (OR) = 1.3, 95% confidence interval (CI) 0.7-2.1), acute lymphocytic leukemia (OR = 1.9, 95% CI 0.9-4.1), and lymphomas (OR = 2.3, 95% CI 0.8-7.1). Adjusting for father's education, associations with father's smoking in the absence of mother's smoking were found for all cancers combined (OR = 1.2, 95% CI 0.8-2.1), acute lymphocytic leukemia (OR = 1.4, 95% CI 0.6-3.1), lymphomas (OR = 1.6, 95% 0.5-5.4), and brain cancer (OR = 1.6, 95% CI 0.7-3.5). In spite of imprecision resulting from small numbers of cases in diagnostic subgroups, these results are suggestive of a possible influence of parents' smoking on childhood cancer.

Adolescent↗
PubMed1991

Occupation and leukemia mortality among men in 16 states: 1985-1987.

The relationship between leukemia and occupation was investigated in a case-control study using death certificates of 5,147 men who died of leukemia (ICD-9 codes 204-208) and 51,470 who died of other causes in 16 U.S. states from 1985 to 1987. Of six occupational activities identified previously as potentially increasing the risk of leukemia, only petroleum refining and rubber manufacturing had excess deaths for all leukemias combined (odds ratios (ORs) = 1.3, 95% confidence intervals (CI) = 0.6-2.8 and 0.9-1.8, respectively). Meat workers and wood workers had elevated mortality from acute lymphocytic leukemia (OR = 2.2, 95% CI = 0.7-7.0 and OR = 1.3, 95% CI = 0.8-2.2, respectively). There was no leukemia excess among farmers or auto mechanics. A survey of 43 other occupational groups indicated a widespread excess of leukemia among white collar occupations, primarily managers and professionals, but none among blue collar workers. This pattern was most pronounced for men under 65 years of age, and existed for all leukemia subtypes and among both blacks and whites. Despite the lack of specific exposure information and other limitations of death certificate data, these results encourage further examination of occupational causes of leukemia.

Black or African American↗
PubMed1991

Influence of paternal age, smoking, and alcohol consumption on congenital anomalies.

The potential effects of paternal exposures on fetal development are of great public and scientific concern, yet few epidemiologic studies have examined this association. Single live births from 1959 to 1966 among 14,685 Kaiser Foundation Health Plan members who participated in the Child Health and Development Studies were analyzed to assess the impact of paternal age, cigarette smoking, and alcohol consumption on the occurrence of birth defects in the offspring. Prevalence odds ratios for anomalies identified by age 5 were analyzed, contrasting exposed to unexposed fathers with adjustment for maternal age, race, education, smoking, and alcohol use. Advanced paternal age was associated with increased risk of preauricular cyst, nasal aplasia, cleft palate, hydrocephalus, pulmonic stenosis, urethral stenosis, and hemangioma. Father's cigarette smoking was more common among children with cleft lip +/- cleft palate, hydrocephalus, ventricular septal defect, and urethral stenosis. Alcohol use by the father was most positively related to the offspring's risk of ventricular septal defect. For both smoking and alcohol use, inverse associations were more common than positive associations. These data generally do not indicate strong or widespread associations between paternal attributes and birth defects. However, because of this study's imprecision, limited ability to isolate defects most likely to be of paternal origin, and the identification of several suggestive associations with age and smoking, further study of this issue would be of value.

Alcohol Drinking↗
PubMed1991

Hospital setting and fetal death during labor among women at low risk.

Intrapartum fetal death in low-risk women at term is a rare obstetric outcome. This is difficult to study because few data sets contain an adequate number of cases for meaningful analysis. This study used data from the 1980 National Natality Survey and National Fetal Mortality Survey, merged with an American Hospital Association annual survey for the same year, to determine whether the frequency of intrapartum fetal death in low-risk women varied by the hospital setting for birth. Stratified analysis was used to assess the relation of level of hospital for delivery with intrapartum fetal death, with control for potential confounding factors. As the level of available perinatal technology decreased, the frequency of intrapartum fetal death increased (odds ratio, 2.0 for Level II and 3.3 for Level I, as compared with Level III hospitals). Even when early neonatal deaths were considered, perinatal mortality remained lowest at Level III facilities (odds ratio, 1.6 for Level II and 2.7 for Level I, as compared with Level III hospitals). The components of intrapartum surveillance that are most effective in the reduction of perinatal mortality have not been identified.

Adolescent↗
PubMed1991

Epidemiologic characteristics of preterm delivery: etiologic heterogeneity.

Preterm delivery (less than 37 weeks completed gestation) is known to result from diverse etiologic pathways, which can be grouped into idiopathic preterm labor, preterm premature rupture of the membranes, and medical complications. Data from publications providing sufficient detail to subdivide preterm delivery cases into these groups were tabulated. In spite of inconsistent terminology and incomplete reporting, patterns were identified. Black women have a markedly higher risk of preterm delivery, which is especially pronounced for preterm premature rupture of the membranes. Idiopathic preterm labor is predominant in lower-risk, white populations. These observations encourage consideration of subcategories of preterm delivery in studies of etiology and prevention.

Abortion, Induced↗
PubMed1991

Invasive cervical cancer and intrauterine device use.

Although the hypothesis that intrauterine device (IUD) use might promote cervical cancer has been considered since the introduction of IUDs in the early 1900s, previous studies are inconclusive. Data collected in interviews with 481 invasive cervical cancer cases and 801 general population controls from Birmingham, Chicago, Denver, Miami and Philadelphia were used to address this issue. These data were analysed to determine the relationship between IUD use and the risk of cervical cancer, with consideration of the type of IUD (copper and inert) and duration of use. A non-significant reduced risk of cervical cancer was associated with copper IUD use, indicated by an adjusted odds ratio (OR) of 0.6 (95% Cl: 0.3-1.2), but virtually no effect was found for inert IUD use (OR = 1.1, 95% Cl: 0.9-1.7). Decreased risk with increased duration of copper IUD use supports a possible protective effect of copper IUD use on the development of invasive cervical cancer.

Adult↗
PubMed1991

Selection of reproductive health end points for environmental risk assessment.

In addition to the challenges inherent in environmental health risk assessment, the study of reproductive health requires thorough consideration of the very definition of reproductive risk. Researchers have yet to determine which end points need to be considered to comprehensively evaluate a community's reproductive health. Several scientific issues should be considered in the selection of end points: the severity of the outcomes, with a trade-off between clinical severity and statistical or biological sensitivity; the relative sensitivity of different outcomes to environmental agents; the interrelationship among adverse outcomes; the baseline frequency of the adverse outcome; evidence from reproductive toxicology; and specificity of reproductive effects from the environmental agent. Simultaneously, practical concerns should be addressed: frequency of occurrence of an event and consequent statistical power to evaluate changes; frequency of prerequisites (e.g., pregnancy) that are necessary to be at risk; time and money resource requirements for measuring the outcome; amenability of the end point to retrospective measurement; and burden of measurement on the population being studied. In this article, we discuss these scientific and practical considerations and recommend that reproductive risk assessment include measures of fecundability (menstrual function, time to pregnancy), fetal loss (clinically recognized miscarriage), and infant health (birth weight, gestational age). Additional methodological research is needed to refine the array of reproductive health measures that need to be examined as a consequence of environmental exposures.

Environmental Exposure↗
PubMed1990

Birthweight patterns in Harare, Zimbabwe.

Few data on birthweight distributions are available for Zimbabwe. This paper reports a study of 2140 births in Harare, Zimbabwe, occurring in April 1986. Births took place in public facilities, which are estimated to serve 85% of the urban population. Mean birthweight for the entire sample is 2970 g, and for singleton livebirths 3059 g. These data suggest that the proportion of low birthweight in Harare attributable to prematurity falls between the patterns of developed and developing countries.

Birth Weight↗
PubMed1990

Magnetic field exposure from electric appliances and childhood cancer.

The effect on childhood cancer of prolonged exposure to 60-H magnetic fields from electric appliances was examined using interview data from a recently completed case-control study. Exposures of children aged 0-14 years whose incident cancers were diagnosed between 1976 and 1983 and who resided in the Denver, Colorado, Standard Metropolitan Statistical Area were compared with those of controls selected by random digit dialing, matched on age, sex, and telephone exchange area. Parents of 252 cases and 222 controls were interviewed at home about the use of electric appliances by the mother during pregnancy (prenatal exposure) and by the child (postnatal exposure). After adjustment for income, prenatal electric blanket exposure was associated with a small increase in the incidence of childhood cancers (odds ratio (OR) = 1.3, 95% confidence interval (CI) 0.7-2.2) that was more pronounced for leukemia (OR = 1.7, 95% CI 0.8-3.6) and brain cancer (OR = 2.5, 95% CI 1.1-5.5). Postnatal exposure to electric blankets was also weakly associated with childhood cancer (OR = 1.5, 95% CI 0.6-3.4), with a larger but imprecise association with acute lymphocytic leukemia (OR = 1.9, 95% CI 0.6-6.5). Water beds and bedside electric clocks were unrelated to childhood cancer incidence. Results are limited by nonresponse and imprecision resulting from the rarity of appliance use, especially for subgroups of cases. Nonetheless, electric blankets, one of the principal sources of prolonged magnetic field exposure, were weakly associated with childhood cancer and warrant a more thorough evaluation.

Adolescent↗
PubMed1990

The effects of sensitivity and specificity of case selection on validity, sample size, precision, and power in hospital-based case-control studies.

The consequences of imperfect sensitivity and specificity in disease diagnosis in epidemiologic studies have conventionally been assessed by models of misclassification which assume a fixed number of study participants. This assumption is not usually applicable to case-control studies in which disease diagnosis is part of the case selection process and sensitivity and specificity will, for a given time period and source of cases, affect the size of the case group. In this paper, a mathematical model that incorporates this is developed in the framework of a hospital-based case-control study. The separate and combined effects of imperfect sensitivity and specificity of case diagnosis on validity, sample size, precision, and power are assessed. The authors conclude that if several diagnostic procedures are available, specificity of case diagnosis should usually take precedence over sensitivity for the sake of validity. Although increasing specificity and sacrificing sensitivity may compromise precision to some extent, the latter can often be fully compensated for by an increased control:case ratio. Imperfect specificity also compromises power despite increased sample size. Since clinical diagnoses tend to focus on high sensitivity and sacrifice some specificity, their uncritical adoption for case recruitment in case-control studies may compromise their validity.

Case-Control Studies↗