Estimation of death rates in US states with small subpopulations

In US states with small subpopulations, the observed mortality rates are often zero, particularly among young ages. Because in life tables, death rates are reported mostly on a log scale, zero mortality rates are problematic. To overcome the observed zero death rates problem, appropriate probability models are used. Using these models, observed zero mortality rates are replaced by the corresponding expected values. This enables logarithmic transformations and, in some cases, the fitting of the eight‐parameter Heligman–Pollard model to produce mortality estimates for ages 0–130 years, a procedure illustrated in terms of mortality data from several states. Copyright © 2014 John Wiley & Sons, Ltd.     

The 1989 revisions of the US Standard Certificates of Live Birth and Death and the US Standard Report of Fetal Death.

The US Standard Certificates and Reports are models used by state vital statistics offices to develop documents for the collection of data about vital events. The 1989 revisions incorporate some major modifications to previous versions. Both the Standard Certificate of Live Birth and the Standard Report of Fetal Death utilize a checkbox format to elicit information on medical and other risk factors affecting the pregnancy, complications of labor and/or delivery, obstetric procedures, method of delivery, congenital anomalies, and abnormal conditions of the newborn. Revisions to the Standard Certificate of Death include modifications to the medical certification section and the addition of decedent's educational attainment. Items requesting information about Hispanic origin are added to all of these documents. The rationale behind these changes and their intended use are discussed.     

Factors That Mediate Racial/Ethnic Disparities in US Fetal Death Rates

Objectives. We sought to determine the importance of socioeconomic factors, maternal comorbid conditions, antepartum and intrapartum complications of pregnancy, and fetal factors in mediating racial disparities in fetal deaths.Methods. We undertook a mediation analysis on a retrospective cohort study of hospital-based deliveries with a gestational age between 23 and 44 weeks in California, Missouri, and Pennsylvania from 1993 to 2005 (n = 7 104 674).Results. Among non-Hispanic Black women and Hispanic women, the fetal death rate was higher than among non-Hispanic White women (5.9 and 3.6 per 1000 deliveries, respectively, vs 2.6 per 1000 deliveries; P < .01). For Black women, fetal factors mediated the largest percentage (49.6%; 95% confidence interval [CI] = 42.7, 54.7) of the disparity in fetal deaths, whereas antepartum and intrapartum factors mediated some of the difference in fetal deaths for both Black and Asian women. Among Hispanic women, socioeconomic factors mediated 35.8% of the disparity in fetal deaths (95% CI = 25.8%, 46.2%).Conclusions. The factors that mediate racial/ethnic disparities in fetal death differ depending on the racial/ethnic group. Interventions targeting mediating factors specific to racial/ethnic groups, such as improved access to care, may help reduce US fetal death disparities.In the United States, there continue to be racial/ethnic disparities in perinatal outcomes such as fetal death.1–4 Studies have identified factors that are associated with increased rates of fetal death overall, including advanced maternal age,5–7 previous cesarean delivery,8 inadequate prenatal care,9 and some chronic medical conditions.10–12 However, none of these studies examined whether higher fetal death rates seen in minority racial/ethnic groups are potentially mediated by factors that occur later in pregnancy.13–15 Understanding these factors and whether these mediating factors differ between racial/ethnic groups will better focus potential interventions to reduce these disparities.We have identified factors that mediate racial/ethnic differences in fetal death rates between 23 and 44 weeks gestation. We grouped factors into 4 areas using the conceptual framework shown in Figure 1. These sets of factors included socioeconomic factors; maternal preexisting comorbid conditions; antepartum and intrapartum factors, primarily complications of pregnancy; and fetal factors, specifically gestational age at delivery.Open in a separate windowFIGURE 1—Hierarchical conceptual framework: racial/ethnic differences in fetal death, California, Missouri, Pennsylvania, 1993–2005.Note. SES = socioeconomic status. The residual disparity in fetal deaths, or fetal deaths unexplained by any of the included factors, is shown as the bottom pathway.     

Dioxins and dibenzofurans in adipose tissue of the general US population and selected subpopulations.

OBJECTIVES. The Environmental Protection Agency's National Human Adipose Tissue Survey (NHATS) was conducted in fiscal year (FY) 1987 to (1) estimate average concentrations of polychlorinated dibenzo-p-dioxins (PCDDs) and polychlorinated dibenzofurans (PCDFs) in the adipose tissue of humans in the US population, (2) identify differences in average concentrations among subpopulations, and (3) compare average concentrations with those from the FY 1982 NHATS. METHODS. Population estimates of the average levels of PCDDs and PCDFs were established on the basis of 865 human adipose tissue specimens collected in FY 1987. Average levels among subpopulations were compared. RESULTS. The average concentration of 2,3,7,8-tetrachlorodibenzo-p-dioxin in the adipose tissue of the US population was 5.38 pg/g, increasing from 1.98 pg/g in children under 14 years of age to 9.40 pg/g in adults over 45. The effect of age was significant for nine compounds. Regional differences in the levels of 2,3,4,7,8-pentachlorinated dibenzofurans were statistically significant, but there were no significant differences associated with sex or race. CONCLUSIONS. The survey provides a baseline of average levels of PCDDs and PCDFs in the adipose tissue of humans in the US population.     

Latitudinal variation of digestive tract cancers in the US and China

Latitude influences the availability of fresh fruits and vegetables (which are associated with cancer protection) and the use of food preservation methods (which are associated with increased cancer). Such dietary differences might be reflected in the frequency of death from cancer of the digestive tract. Female mortality rates for states and provinces of the US and China, both of which cover a wide latitude range, were chosen to investigate latitude- and time-related changes. Mortality for cancer of the stomach, liver, and rectum did increase with latitude in both nations, which is consistent with the hypothesis. Exceptions were cancer of the colon and esophagus; these cancers had a variable association with latitude and did not decline markedly in the US by 1970-1979 as did mortality rates from cancer of the other digestive tract sites. Increased refrigeration and improved transportation, both of which result in increased consumption of fresh fruits and vegetables, and decreased use of older food preservation methods may be responsible for the US decline in mortality rates from stomach, liver, and rectal cancers.     

The effect of rate denominator source on US fatal occupational injury rate estimates

BACKGROUND: The Current Population Survey (CPS) is often used as a source of denominator information for analyses of US fatal occupational injury rates. However, given the relatively small sample size of the CPS, analyses that examine the cross-classification of occupation or industry with demographic or geographic characteristics will often produce highly imprecise rate estimates. The Decennial Census of Population provides an alternative source for rate denominator information. We investigate the comparability of fatal injury rates derived using these two sources of rate denominator information. METHODS: Information on fatal occupational injuries that occurred between January 1, 1983 and December 31, 1994 was obtained from the National Traumatic Occupational Fatality surveillance system. Annual estimates of employment by occupation, industry, age, and sex were derived from the CPS, and by linear interpolation and extrapolation from the 1980 and 1990 Census of Population. Fatal injury rates derived using these denominator data were compared. RESULTS: Fatal injury rates calculated using Census-based denominator data were within 10% of rates calculated using CPS data for all major occupation groups except farming/forestry/fishing, for which the fatal injury rate calculated using Census-based denominator data was 24.69/100,000 worker-years and the rate calculated using CPS data was 19.97/100,000 worker-years. The choice of denominator data source had minimal influence on estimates of trends over calendar time in the fatal injury rates for most major occupation and industry groups. CONCLUSIONS: The Census offers a reasonable source for deriving fatal injury rate denominator data in situations where the CPS does not provide sufficiently precise data, although the Census may underestimate the population-at-risk in some industries as a consequence of seasonal variation in employment.     

Semivolatile organic compounds in adipose tissue: estimated averages for the US population and selected subpopulations.

OBJECTIVES: The fiscal year (FY) 1986 Environmental Protection Agency National Human Adipose Tissue Survey (NHATS) was conducted to estimate average concentrations of 111 semivolatiles in human adipose tissue within the US general population and selected subpopulations. METHODS: Population and subpopulation estimates of average semivolatile concentrations were established from 671 adipose tissue specimens pooled across 50 analytical samples. RESULTS: Among polychlorinated biphenyls (PCBs), average concentrations for the group aged 45 and older were from 188% to 706% higher than for the 0- through 14-year-old age group. Similar increases with age were observed for pesticides. Geographic effects on average concentration were mixed, and no significant race or sex effects were observed. Statistically significant increases from FY 1982 NHATS results were observed for PCBs and hexachlorobenzene, whereas a decrease from FY 1982 was significant for beta-BHC (benzene hexachloride). Increases from FY 1984 NHATS results were significant for p,p-DDT (dichlordiphenylethylene), p,p-DDE (dichlordiphenyldichlor), hexachlorobenzene, and PCBs. CONCLUSIONS: The survey establishes baseline average levels of semivolatile compounds in the adipose tissue of US residents.     

Diurnal variation in postabsorptive resting metabolic rate and diet-induced thermogenesis

Postabsorptive resting metabolic rate (RMR) and diet-induced thermogenesis (DIT) were repeatedly assessed on different days in 10 young men of normal weight on mornings and afternoons. No significant diurnal variation was found in RMR, DIT, total postprandial substrate oxidation, and overall postprandial nutrient balances. The pattern of postprandial substrate oxidation indicated an increased glucose oxidation in the first hour after ingestion of a meal on morning tests compared with afternoon tests. This was probably related to differences in the degree of the postabsorptive state, ie, 12-14 h on morning tests and 6-7 h on afternoon tests.     

Intra-individual variation in resting metabolic rate during the menstrual cycle

Little information exists on the extent of day-to-day intra-individual variation in resting metabolic rate (RMR) in women. The present study has investigated the intra-individual variation in RMR of women during the menstrual cycle. Nineteen women (naturally cycling non-pill users) were recruited to the study. Anthropometric and RMR measurements were taken at least three times per week for the duration of one complete menstrual cycle; measurements were taken for a second, consecutive cycle in eight of the nineteen subjects. RMR was measured by indirect calorimetry using a ventilated hood system under standardized conditions. The measurements made throughout each complete menstrual cycle were averaged and the levels of inter- and intra-individual variation in RMR were assessed by determining the CV (%). Mean RMR of the group was 5686 (sd 674) kJ/d; inter-individual variation in RMR was 11.8 %. There were wide differences in the intra-individual variation in RMR of women (CV range 1.7-10.4 %). The CV in ten subjects was small (2-4 %), while the CV in nine women was high (5-10 %), indicating a significant variation in RMR during the menstrual cycle in certain subjects. Using statistical models, it has been shown that there was a significant effect on RMR due to a subject-specific level of variability; this was the case even when accounting for a possible training effect. In conclusion, the findings from our present study show that RMR cannot be assumed to be 'stable' in all women. The implications of intra-individual variation in RMR and its impact on energy balance needs further research.     

Diurnal variation in peak expiratory flow rate among grain elevator workers

The diurnal variation (DV) in peak expiratory flow rate (PEFR) has been studied among 132 grain elevator workers who accomplished three daily measurements of PEFR during three weeks. DV was calculated as the difference between the highest and the lowest PEFR as a percentage of the mean PEFR on each day. For the whole group the median was 5.9%. DV was higher among smokers and among workers with work related pulmonary symptoms. Analysis of variance showed that only age (p = 0.012) and smoking (p = 0.016) had a significant effect on DV. Pulmonary symptoms, total IgE, and duration of occupation had no independent impact on DV, whereas the exposure level of grain dust tended (p = 0.082) to have an independent effect. Twelve workers had an abnormally high DV (greater than 20%), of whom seven showed no signs of obstructive respiratory disease by spirometry. If only a single spirometric test had been performed the tentative diagnosis of bronchial asthma could have been missed in these seven workers.     

Diurnal variation in peak expiratory flow rate among polyvinylchloride compounding workers

The diurnal variation in peak expiratory flow rate (PEFR) was studied in 24 mixers and 24 non-mixers in three polyvinylchloride (PVC) compounding plants and 24 non-PVC controls from a marine police workshop. The three groups (all men) were matched for age, race, and smoking. The mean respirable dust concentration (essentially PVC dust) was 1.6 mg/m3 for mixers and 0.4 mg/m3 for nonmixers. The mean diurnal variation in PEFR of the mixers was 6.5%. This was significantly higher than the 4.8% for non-mixers and 4.3% for the non-PVC controls. Six mixers had a diurnal variation of more than 15% on at least one day compared with none among the other two groups. Twenty nine per cent of mixers complained of wheezing compared with 4% of non-mixers and none among non-PVC workers. These differences were significant. Forced expiratory volume in one second (FEV1) for the mixers was 10% below the predicted values whereas that of non-PVC workers was 2% below predicted values. The study indicates a significant acute airway constriction from occupational exposure to PVC dust.     

Heart rate variation and serum dopamine-beta-hydroxylase activity in workers exposed to vibration

Tests of autonomic nervous function were conducted on 38 workers who had been exposed to vibration [16: VWF(+) group, 22: VWF(-) group, VWF: vibration-induced white finger] and 17 workers who had not been exposed to vibration (control group). Measurements were made of R-R interval variation of the electrocardiogram at rest and during deep breathing, and serum dopamine-beta-hydroxylase (DBH) activity during an immersion test of the hand in 10 degrees C water. Heart-rate variation related to respiratory arrhythmia indicates parasympathetic activity, and serum DBH activity is regarded as an indicator of sympathetic activity. The variations in the R-R interval during deep breathing were smallest in the VWF(+) group, followed by the VWF(-) group (P less than 0.05 and P less than 0.01, compared with the control group). The DBH activity of the VWF(+) group was larger than those of the VWF(-) group and the control group, however, the differences were small and not statistically significant. The reduced R-R interval variations in the VWF(+) and the VWF(-) groups support the hypothesis that autonomic nervous function can be affected by exposure to vibration. The change of DBH activity induced by cold exposure may be an unsuitable index of sympathetic tone. Further study of the autonomic nervous function in workers with vibration syndrome is recommended.     

Effect of area poverty rate on cancer screening across US communities

STUDY OBJECTIVE: To analyse the contextual effect of area poverty rate on never having been screened for breast, cervical, and colorectal cancer by (1) describing the extent of the variation in screening behaviours among 98 US metropolitan areas; (2) determining if the variation in lack of screening can be explained by differences in the characteristics of the persons who resided in these areas; and (3) determining if living in a metropolitan area with a higher poverty rate increased the likelihood of never having been screened for cancer over and above individual characteristics. DESIGN: Cross sectional survey using data from the 2002 Behavioral Risk Factor Surveillance System. Multilevel logistic regression included both individual level factors as well as area poverty rate. SETTING: Ninety eight areas across the USA. PARTICIPANTS: Over 118 000 persons residing in 98 areas; a sample aimed at estimating 48.3% of the US population age 18 or older. MAIN RESULTS: After adjustment for individual level factors, increasing area level poverty rate (per 5%) remained associated with never having had a mammogram (odds ratio (OR) = 1.28, 95% confidence interval (CI): 1.03 to 1.37); clinical breast examination (OR = 1.28, 95% CI: 1.11 to 1.48), colonoscopy/sigmoidoscopy (OR = 1.10, 95% CI: 1.01 to 1.19), and a faecal occult blood test (OR = 1.19, 95% CI: 1.12 to 1.27). Poverty rate was not independently associated with never having had a Pap smear (OR = 1.12; 95% CI: 0.90 to 1.41). The size of the variance among metropolitan or micropolitan statistical areas (MMSAs) varied by type of screening test, with intraclass correlation coefficients ranging from 4.9% (never having had a Pap smear) to 1.2% (never having had a colonoscopy/sigmoidoscopy). CONCLUSIONS: Area poverty rate was independently associated with never having been screened for breast and colorectal cancer, but not cervical cancer. The size of the variance among MMSAs was modest at best.     

Diurnal variation in peak expiratory flow rate among grain elevator workers.

The diurnal variation (DV) in peak expiratory flow rate (PEFR) has been studied among 132 grain elevator workers who accomplished three daily measurements of PEFR during three weeks. DV was calculated as the difference between the highest and the lowest PEFR as a percentage of the mean PEFR on each day. For the whole group the median was 5.9%. DV was higher among smokers and among workers with work related pulmonary symptoms. Analysis of variance showed that only age (p = 0.012) and smoking (p = 0.016) had a significant effect on DV. Pulmonary symptoms, total IgE, and duration of occupation had no independent impact on DV, whereas the exposure level of grain dust tended (p = 0.082) to have an independent effect. Twelve workers had an abnormally high DV (greater than 20%), of whom seven showed no signs of obstructive respiratory disease by spirometry. If only a single spirometric test had been performed the tentative diagnosis of bronchial asthma could have been missed in these seven workers.     

Diurnal variation in peak expiratory flow rate among polyvinylchloride compounding workers.

The diurnal variation in peak expiratory flow rate (PEFR) was studied in 24 mixers and 24 non-mixers in three polyvinylchloride (PVC) compounding plants and 24 non-PVC controls from a marine police workshop. The three groups (all men) were matched for age, race, and smoking. The mean respirable dust concentration (essentially PVC dust) was 1.6 mg/m3 for mixers and 0.4 mg/m3 for nonmixers. The mean diurnal variation in PEFR of the mixers was 6.5%. This was significantly higher than the 4.8% for non-mixers and 4.3% for the non-PVC controls. Six mixers had a diurnal variation of more than 15% on at least one day compared with none among the other two groups. Twenty nine per cent of mixers complained of wheezing compared with 4% of non-mixers and none among non-PVC workers. These differences were significant. Forced expiratory volume in one second (FEV1) for the mixers was 10% below the predicted values whereas that of non-PVC workers was 2% below predicted values. The study indicates a significant acute airway constriction from occupational exposure to PVC dust.     

Lymphocyte subpopulations in solvent-exposed workers

Summary To estimate the cellular immune response of workers highly exposed to mixtures of organic solvents, subpopulations of peripheral blood lymphocytes (PBLs) were analyzed. For this, the PBLs of nine floorers (aged 25–58 years, exposure time 8–35 years) were subsequently labelled with monoclonal antibodies OKT 4, OKT 8, OKT 11, anti-Leu 7 and anti-Leu 12. Analysis was made by a FACS IV cell sorter (Becton-Dickinson, USA). The control group consisted of matched pairs of healthy donors. In the exposed group we found a decrease in the OKT 11 (all) T cell fraction, a decrease in the OKT 4 helper cells, an increase in the anti-Leu 7 positive cells, mostly natural killer cells, an important increase in anti-Leu 12 labelled T cells, i.e., human B-lymphocytes, and no differences in the OKT8 suppressor cells. Total fluorescence intensity profiles between the exposed and the unexposed group did not differ, i.e., the marker density on the cell surfaces remained unchanged. Similar changes in lymphocyte subpopulations are found in states of immunodeficiency and immunogenetic forms of aplastic anemia, a disease whose etiological relationship may be due to long-term exposure to organic solvents.