Potential confounding of particulate matter on the short-term association between ozone and mortality in multisite time-series studies

BACKGROUND: A critical question regarding the association between short-term exposure to ozone and mortality is the extent to which this relationship is confounded by ambient exposure to particles. OBJECTIVES: We investigated whether particulate matter < 10 and < 2.5 microm in aerodynamic diameter (PM(10) and PM(2.5)) is a confounder of the ozone and mortality association using data for 98 U.S. urban communities from 1987 to 2000. METHODS: We a) estimated correlations between daily ozone and daily PM concentrations stratified by ozone or PM levels; b) included PM as a covariate in time-series models; and c) included PM as a covariate as in d), but within a subset approach considering only days with ozone below a specified value. RESULTS: Analysis was hindered by data availability. In the 93 communities with PM(10) data, only 25.0% of study days had data on both ozone and PM(10). In the 91 communities with PM(2.5) data, only 9.2% of days in the study period had data on ozone and PM(2.5). Neither PM measure was highly correlated with ozone at any level of ozone or PM. National and community-specific effect estimates of the short-term effects of ozone on mortality were robust to inclusion of PM(10) or PM(2.5) in time-series models. The robustness remains even at low ozone levels (< 10 ppb) using a subset approach. CONCLUSIONS: Results provide evidence that neither PM(10) nor PM(2.5) is a likely confounder of observed ozone and mortality relationships. Further investigation is needed to investigate potential confounding of the short-term effects of ozone on mortality by PM chemical composition.     

基于二胎政策下女性分娩次数与肥胖的关系

目的高产次被认为是女性肥胖的危险因素。本研究探讨新疆墨玉县女性产次与全身性肥胖、中心性肥胖的相关性。方法选取新疆和田墨玉县参与《新疆多民族自然人群队列建设研究》的35～74岁且有至少1次活产记录的女性为研究对象。使用体质指数(BMI)评估全身性肥胖,采用腰围(WC)和腰身比(WHt R)评估中心性肥胖。采用多元logistic回归模型分析产次与不同类型肥胖之间的关联。结果共纳入6 987名研究对象。研究对象全身性肥胖患病率为56.9%(61.66/6 987),通过WC和WHt R计算的中心性肥胖患病率分别为84.3%(5 897/6 987)和88.2%(3 977/6 987)。3种肥胖指标均值在产次为2中最低,WC和WHt R均值在不同产次中差异有统计学意义(P<0.05)。调整潜在的混杂因素后,产次与3种肥胖指标均相关,BMI、WC、WHt R评估肥胖OR值分别为1.218(95%CI:1.033～1.436)、1.384(95%CI:1.130～1.695)和1.429(95%CI:1.144～1.785)。结论高产次与肥胖风险,尤其是与中心性肥胖呈正相关。产次与3种中...     

Income and mortality: the shape of the association and confounding New Zealand Census-Mortality Study, 1981-1999

OBJECTIVE: To determine the shape of the income-mortality association, before and after adjusting for confounding by other socioeconomic variables. METHODS: Poisson regression analyses were conducted on 11.7 million years of follow-up of 25-59 year old New Zealand census respondents spanning four separate cohort studies (1981-1984, 1986-1989, 1991-1994, and 1996-1999). RESULTS: Mortality among low-income people was approximately two times that among high-income people. Adjustment for potential socioeconomic confounders (marital status, education, car access, and neighbourhood socioeconomic deprivation) halved the strength of the income-mortality association, but did not appreciably change the shape of the association. Further adjustment for labour force status largely removed the income-mortality association. The association of non-transformed income with mortality was non-linear, with a flattening out of the slope at higher incomes. Both the logarithm and rank of income appeared to have a better linear fit with the mortality rate, although the association of mortality with the logarithm of income flattened out notably at low incomes. CONCLUSIONS: Much, but not all, of the crude association of income with mortality could be due to confounding. Adjusting income-mortality associations for labour force status (also a proxy for health status) is problematic: on the one hand, it over-adjusts the association as poor health will be on the pathway from income to mortality; on the other hand, it appropriately adjusts for both confounding by labour force status and reverse causation whereby income changes as a result of poor health. Both logarithmic and rank transformations of income have a reasonable linear fit with income.     

Temporal variation in the association between benzene and leukemia mortality

BACKGROUND: Benzene is a human carcinogen. Exposure to benzene occurs in occupational and environmental settings. OBJECTIVE: I evaluated variation in benzene-related leukemia with age at exposure and time since exposure. METHODS: I evaluated data from a cohort of 1,845 rubber hydrochloride workers. Benzene exposure-leukemia mortality trends were estimated by applying proportional hazards regression methods. Temporal variation in the impact of benzene on leukemia rates was assessed via exposure time windows and fitting of a multistage cancer model. RESULTS: The association between leukemia mortality and benzene exposures was of greatest magnitude in the 10 years immediately after exposure [relative rate (RR) at 10 ppm-years = 1.19; 95% confidence interval (CI), 1.10-1.29]; the association was of smaller magnitude in the period 10 to < 20 years after exposure (RR at 10 ppm-years = 1.05; 95% CI, 0.97-1.13); and there was no evidence of association > or = 20 years after exposure. Leukemia was more strongly associated with benzene exposures accrued at > or = 45 years of age (RR at 10 ppm-years = 1.11; 95% CI, 1.04-1.17) than with exposures accrued at younger ages (RR at 10 ppm-years = 1.01; 95% CI, 0.92-1.09). Jointly, these temporal effects can be efficiently modeled as a multistage process in which benzene exposure affects the penultimate stage in disease induction. CONCLUSIONS: Further attention should be given to evaluating the susceptibility of older workers to benzene-induced leukemia.     

Assessing confounding, effect modification, and thresholds in the association between ambient particles and daily deaths

I examined the relationship between daily deaths and airborne particles in 10 U.S. cities with varying climatic conditions and seasons in which particle concentrations were high. Airborne particles were associated with significant increases in daily deaths [0.67% increase for a 10 microg/m(3) increase in particles; 95% confidence interval (CI), 0.52-0.81%]. This association was the same in summer and winter. To examine potential confounding by other pollutants, I regressed city- and season-specific effect sizes against the relationship between airborne particles and other pollutants. Controlling for other pollutants did not substantially (or significantly) change the estimated effect of airborne particles. Socioeconomic differences between cities likewise did not modify the effect. The increase in daily deaths that occurred out of hospitals (0.89% per 10 microg/m(3); CI, 0.67-1.10%) was substantially greater than the increase in deaths in hospitals (0. 49%; CI, 0.31-0.68%). This is consistent with results previously reported in Philadelphia, Pennsylvania, and suggests that the particle-associated deaths are not just being brought forward by a few days. It is also consistent with recent animal and human studies of the mechanisms of particle toxicity.     

The association between gender,family status and mortality

Aim  To analyse marital and gender differentials in mortality.Subjects and methods  The causes of death in Germany were analyzed in detail to determine odds ratios (OR) for all causes and the four main causes of death.Results  Mortality rates were nearly twice as high for men as for women. Mortality rates for unmarried men were more than twice as high as those for married men (OR 2.43–2.50); the ORs for women were considerably lower (1.74 to 1.75). For men, the ORs were higher for those causes of death influenced by health-risk behaviour.Conclusion  In terms of health gains, marriage seems to be more beneficial to men than to women. Particularly for men, marriage provides stronger protection against causes of death that are related to health-risk behaviour (smoking, drinking, risky driving) and to unhealthy working conditions.

Effect of previous-winter mortality on the association between summer temperature and mortality in South Korea

Background

It has recently been postulated that low mortality levels in the previous winter may increase the proportion of vulnerable individuals in the pool of people at risk of heat-related death during the summer months.

Objectives

We explored the sensitivity of heat-related mortality in summer (June–August) to mortality in the previous winter (December–February) in Seoul, Daegu, and Incheon in South Korea, from 1992 through 2007, excluding the summer of 1994.

Methods

Poisson regression models adapted for time-series data were used to estimate associations between a 1°C increase in average summer temperature (on the same day and the previous day) above thresholds specific for city, age, and cause of death, and daily mortality counts. Effects were estimated separately for summers preceded by winters with low and high mortality, with adjustment for secular trends.

Results

Temperatures above city-specific thresholds were associated with increased mortality in all three cities. Associations were stronger in summers preceded by winters with low versus high mortality levels for all nonaccidental deaths and, to a lesser extent, among persons ≥ 65 years of age. Effect modification by previous-winter mortality was not evident when we restricted deaths to cardiovascular disease outcomes in Seoul.

Conclusions

Our results suggest that low winter all-cause mortality leads to higher mortality during the next summer. Evidence of a relation between increased summer heat-related mortality and previous wintertime deaths has the potential to inform public health efforts to mitigate effects of hot weather.     

Investigation of the association between excess winter mortality and socio-economic deprivation

BACKGROUND: Excess winter mortality is higher in England and Wales than in other European countries with similar or lower average winter temperatures. It might be expected that excess winter mortality would be higher in areas with greater socio-economic deprivation, and if this were so preventive interventions could be directed at populations in these areas. The association between deprivation and excess winter mortality has not been adequately investigated in the past. The aim of this study was to look at the association between excess winter mortality and socio-economic deprivation, so that policy decisions to reduce this excess mortality could be appropriately directed. METHODS: Super Profile groups derived from the 1991 Census were used as a measure of socio-economic status. The age-standardized excess winter death index (EWDI) was calculated for each Super Profile group, for the population of Bradford. The EWDI was also calculated for the manufacturing districts (Office for National Statistics area classification), a relatively deprived group, and compared with that for England and Wales. RESULTS: No significant trend was found in age-standardized excess winter mortality across the Super Profile groups. The manufacturing districts had a similar EWDI to the national value. CONCLUSION: Excess winter mortality is not associated with deprivation. Further research to identify the important aetiological factors and appropriate interventions to reduce excess winter mortality is needed.     

The association between maternal ratings of child health interviews and maternal and child characteristics

BACKGROUND: Doctors develop the skills needed to interview parents and children in paediatric settings by practice and by receiving feedback during their medical training. Interviewed parents are ideally placed to provide evaluations of these skills. If parents, as consumers of health care services, are to be consulted, it is important to determine whether factors other than interview skills affect their evaluations. OBJECTIVES: Our aim was to examine the relationship between maternal satisfaction ratings of student doctor interviews, and maternal and child characteristics. METHODS: Sixty mothers of children attending the paediatric medical out-patient clinic at the Women's and Children's Hospital, South Australia were allocated randomly to rate one of four video-taped final year student doctor interviews (15 mothers per interview). The level of skills displayed by the student doctor differed in each interview. Maternal satisfaction was measured using the Medical Interview Satisfaction Scale (MISS) and the Interpersonal Skills Rating Scale (IPS), and interview ratings were compared for a number of maternal and child characteristics. RESULTS: No significant associations were observed between maternal satisfaction ratings and any maternal or child characteristics other than lower satisfaction associated with previous experience of a real student doctor interview (P <0.01). The interview seen by mothers predicted 53% (MISS) and 65% (IPS) of the variance in maternal satisfaction ratings. After controlling for the interview type, the maternal and child characteristics studied predicted 17% additional variance in MISS scores and 7% in IPS scores. CONCLUSION: The quality of the interview skills demonstrated was the principle determinant of maternal satisfaction ratings.     

Space-time confounding adjusted determinants of child HIV/TB mortality for large zero-inflated data in rural South Africa

South Africa is experiencing a major burden of HIV/TB. We used longitudinal data from the Agincourt sub-district in rural northeast South Africa over the years 2000 to 2005. A total of 187 HIV/TB deaths were observed among 16,844 children aged 1-5 years coming from 8,863 households. In this paper we used Bayesian models to assess risk factors for child HIV/TB mortality taking into account the presence of spatial correlation. Bayesian zero inflated spatiotemporal models were able to detect hidden patterns within the data. Our main finding was that maternal orphans experienced a threefold greater risk of HIV/TB death compared to those with living mothers (AHR=2.93, 95% CI[1.29;6.93]). Risk factor analyses which adjust for person, place and time provide evidence for policy makers that includes a spatial distribution of risk. Child survival is dependent on the mother's survival; hence programs that promote maternal survival are critical.     

Evolution of the association between parental and child smoking in Finland between 1977 and 2005

OBJECTIVES: To study changes in the family smoking profile and in the association between parental and child smoking from 1977 to 2005. METHODS: Data was based on biennial surveys using nationally-representative samples of 14-18-year-old Finns (n=58,279). Response rate ranged between 88% (1977) and 65% (2005). Parental smoking categories were: two smoking parents, smoking father, smoking mother, both currently non-smokers but one or both ex-smokers, and two never-smoking parents. Child smoking categories were: experimental, daily, and never. Associations between parental and child smoking were examined using multinomial logistic regression models. RESULTS: Over the study period, the proportion of never-smoking families (child and parents never-smokers) increased (9% vs. 18%). Age, sex, family structure, and survey decade adjusted odds ratios for child's daily smoking were 6.9 (95% CI: 6.4, 7.5) when both parents smoked, 4.7 (95% CI: 4.3, 5.2) when mother smoked, 3.8 (95% CI: 3.5, 4.1) when father smoked, and 2.8 (95% CI: 2.6, 2.9) when one/both were ex-smokers compared with children of never-smoking parents. Only a few non-systematic interactions between parental smoking and survey decade were found. CONCLUSIONS: The proportion of totally smoke-free families increased substantially. Association between parental and child smoking persisted strong and mainly similar over time.     

Age and race impact the association between BMI and CVD mortality in women

OBJECTIVES: In previous studies, we have shown that obesity is associated with increased cardiovascular disease (CVD) mortality in white women but not in black women. Earlier research suggests that body mass index (BMI) has a greater effect on CVD mortality in younger white females than older white females, whereas this relationship in black women is not as clear. This study examines the effect of age on the association of BMI to CVD in black and white women. METHODS: The Black Pooling Project includes data on 2,843 black women with 50,464 person-years of follow-up, and 12,739 white women with 214,606 person-years of follow-up. A Cox proportional hazards model was used to examine the association between BMI and CVD mortality for specific age/race groups. The younger group was < 60 years of age and the older group was > 60 years of age. RESULTS: In younger white women, the relative risk (95% confidence interval [CI]) for CVD mortality was significant in obese women (BMI > 30 kg/m2) vs. women of normal weight (BMI 18.5-24.9 kg/m2) (1.59 [CI 1.20, 2.09]). Similarly, in older white women, the relative risk for CVD mortality in obese women vs. women of normal weight was significant (1.21 [CI 1.04, 1.41]). There were no such associations for black women. Overweight (BMI 25-29.9 kg/m2) was not associated with increased risk in black or white women. CONCLUSION: These findings indicate that obesity is associated with a significantly greater risk of CVD mortality among white women, with the strongest association among white women < 60 years of age.     

A new simple primary care morbidity score predicted mortality and better explains between practice variations than the Charlson index

ObjectivesAdjustment for morbidity is important to ensure fair comparison of outcomes between patient groups and health care providers. The Quality and Outcomes Framework (QOF) in UK primary care offers potential for developing a standardized morbidity score for low-risk populations.Study Design and SettingRetrospective cohort study of 653,780 patients aged 60 years or older registered with 375 practices in 2008 in a large primary care database (The Health Improvement Network). Half the practices were randomly selected to derive a morbidity score predicting 1-year mortality; the others assessed predictive performance.ResultsNine chronic conditions were robust copredictors (hazard ratio = ≥1.2) of mortality independent of age and sex, producing high predictive discrimination (c-statistic = 0.82). An individual's QOF score explained more between practice variation in mortality than the Charlson index (46% vs. 32%). At practice level, mean QOF score was strongly correlated with practice standardized mortality ratios (r = 0.64), explaining more variation in practice death rates than the Charlson index.ConclusionA simple nine-item score derived from routine primary care recording provides a morbidity index highly predictive of mortality and between practice variation in older UK primary care populations. This has utility in research and health care outcome monitoring and can be easily implemented in other primary and ambulatory care settings.     

Empirical findings on the association between education and child health status: discussion

In this discussion of the empirical findings on the association between education and child health status, it is important to note the important contributions of Cochrane and Caldwell. Most of the evidence comes from aggregate studies, and it shows certain facts significant from the perspective of policies. The association between education and child mortality is found in a variety of conditions, and mother's education appears to have a stronger effect than father's education. This finding warrants a discussion of the mechanism of this effect. It is also relevant for intervention programs. It is clear that despite much research the exact nature of the association between education and child mortality is not well known, and the mechanism should not be oversimplified. The errors in basic data may be impressive, and at times it is unknown how much the real "effect" of education on mortality is overestimated or underestimated. Selecting and operationalizing variables is an important step in the attempt to understand the nature of the relationship between education and mortality. When dealing with population censuses or other sources of systematic information, efforts are restricted to available information. Operational variables are usually proxies to the real theoretical variables of interest, and sometimes they are rather poor indicators. The theoretical frame of analysis is more important when the researcher designs the collection of information. The point that must be emphasized is that both the changes in mortality and education are occurring in the 3rd world countries within a historic transition from precapitalistic modes of production to relatively advanced, dependent, capitalistic development. Examples are included which show the importance of considering the contextual, historical conditions which, to a certain extent, are determining both parents' education and child mortality as well as the association between them. Another point to be considered is that both the magnitude of mortality and the low educational levels are shocking in several underdeveloped countries with avoidable deaths running to the order of several million each year. The final point concerns informal education. Recently, the idea of extending health services through primary health care has received important consideration. Those programs emphasize health education and certain community participation in health programs, but these facts are not reflected in the usual years of schooling index. In sum, the study of the association of parents' education and child mortality must be understood in the historic perspective of the different and complex social changes that are taking place in the societies of the 3rd world.     

Parents' child care experience: effects of sex and parity

A sample of 94 couples was surveyed to determine effects on child care experience associated with sex, parity, and various other demographic variables; experience was measured by scores on the Experience with Young Children Scale. As expected, women had higher scores than men; experience was a linear function of parity for men, but not for women, and was unrelated to scores on the Attitudes Toward Women Scale. Couples tended to resemble each other in experience, even when parity was statistically controlled. Discussion emphasized implications for sex differences in child care responsibility, and the need for additional attention to socialization for the child caregiver role.