Cardiovascular admission risk attributable to hot apparent temperature: a study in a rural area of northwest China

Cardiovascular disease (CVD) is the leading cause of mortality worldwide, posing a significant threat to public health. Research on the relationship between CVD and temperature has primarily focused on developed urban settings, with limited studies conducted in rural regions with lower levels of development. Additionally, compared to relative risks, attributable risks can provide more information when assessing the risk of CVD hospitalizations associated with exposure to apparent temperature (AT). Apparent temperature is a composite temperature index that takes into account both meteorological factors and temperature, providing an objective reflection of human thermal sensation. Therefore, this study investigates the impact of AT on CVD hospitalization and quantifies the burden of CVD admission in the rural areas of China. We employed the distributed lag non-linear model (DLNM) to estimate the relationship between AT and the relative risk (RR) of CVD hospitalization. Finally, we used attributable risk methods to quantify this relationship further.

The added effects of cold spells on stroke admissions: Differential effects on ischemic and hemorrhagic stroke

BACKGROUND

Epidemiological evidence suggests an association between low ambient temperature and stroke risk, but available data are limited particularly on associations with different stroke subtypes.

AIMS

The aim of this study is to estimate the relationship between cold spells and stroke admissions, including the effect of cold spells on different stroke subtypes (ischemic stroke and intracerebral hemorrhage (ICH)).

METHODS

A total of 144,405 stroke admissions from the Tianjin Centre for Health and Meteorology Multidisciplinary Innovation in China, covering the period from January 2016 to December 2020, were studied, as well as meteorological and air pollutant data. A generalized additive model with a distributed lag nonlinear model was employed to assess the relationship, considering 12 different definitions of a cold spell based on various temperature thresholds and durations. The analysis controlled for lagged and nonlinear effects of temperature. Analyses were performed on all strokes as well as ischemic stroke and ICH.

RESULTS

There was a significant increase in stroke admissions during cold spells. Generally, the increased risk during cold spells increased as the temperature threshold decreased, but was not significantly affected by the duration. The optimal model was obtained using the cold-spell definition based on an average daily temperature below the 10th percentile (0.11°C) for 2 or more consecutive days. According to this model, the effect of cold spells on ischemic stroke admissions had a significant lag effect and was long-lasting, with a single-day effect occurring on lag 7d, peaking on lag 13d (relative risk (RR) = 1.05; 95% confidence interval (CI) = 1.02 to 1.09), and lasting until lag 20d. In contrast, the effect on ICH was immediate and short-lived, with the most significant single-day effect occurring on the current day (RR = 1.17; 95% CI = 1.06 to 1.29) and limited within 3 days. 14.15% of stroke cases could be attributed to cold spells, with ICH exhibiting a higher burden than ischemic stroke except for strict temperature threshold definitions.

CONCLUSION

Cold spells are associated with an increased stroke risk. Different patterns of association were seen for different stroke subtypes. The effect on ischemic stroke had a lag effect and a longer duration, whereas the effect on ICH had an immediate effect and a shorter duration. These findings support the development and improvement of stroke cold-spell early warning systems and highlight the importance of public health interventions to mitigate the adverse health impacts of cold spells.

Prevalence of and risk factors for sarcopenia in community-dwelling people: The Vietnam Osteoporosis Study

BACKGROUND

Sarcopenia is a geriatric disease characterized by the progressive and generalized loss of skeletal lean mass and strength with age. The prevalence of sarcopenia in the Vietnamese population is unknown. This study sought to estimate the prevalence of and risk factors for sarcopenia among community-dwelling individuals in Vietnam.

METHODS

This cross-sectional study is part of the ongoing Vietnam Osteoporosis Study project. The study involved 1308 women and 591 men aged 50 years and older as at 2015 (study entry). Whole-body dual-energy X-ray absorptiometry was used to measure the appendicular skeletal lean mass. Anthropometric and clinical data were collected using a structured questionnaire. Sarcopenia was defined according to the criteria proposed by the Asian Working Group for Sarcopenia in 2019. Logistic regression analysis was used to determine the association between potential risk factors and sarcopenia.

RESULTS

The prevalence of sarcopenia in women and men was 14% (n = 183) and 16% (n = 83), respectively. Age (odds ratio [OR] per 10 years = 1.37; 95% confidence interval [CI] 1.26-1.48) and being underweight (OR = 1.61; 95% CI 1.00-2.58) were independently associated with increased risk of sarcopenia. The combination of low physical activity, being underweight and advancing age accounted for ~27% of sarcopenic patients. However, most of the attributable fraction was due to ageing.

CONCLUSIONS

Sarcopenia is common in community-dwelling Vietnamese adults, particularly those with advancing age, who are underweight and with low physical activity.

The role of absolute humidity in influenza transmission in Beijing, China: risk assessment and attributable fraction identification

To assess the impact of absolute humidity on influenza transmission in Beijing from 2014 to 2019, we estimated the influenza transmissibility via the instantaneous reproduction number (Rt), and evaluated its nonlinear exposure-response association and delayed effects with absolute humidity by using the distributed lag nonlinear model (DLNM). Attributable fraction (AF) of Rt due to absolute humidity was calculated. The result showed a significant M-shaped relationship between Rt and absolute humidity. Compared with the effect of high absolute humidity, the low absolute humidity effect was more immediate with the most significant effect observed at lag 6 days. AFs were relatively high for the group aged 15-24 years, and was the lowest for the group aged 0-4 years with low absolute humidity. Therefore, we concluded that the component attributed to the low absolute humidity effect is greater. Young and middle-aged people are more sensitive to low absolute humidity than children and elderly.

Spatiotemporal Patterns of Esophageal Cancer Burden Attributable to Behavioral, Metabolic, and Dietary Risk Factors From 1990 to 2019: Longitudinal Observational Study

BACKGROUND

Esophageal cancer (EC) is the sixth leading cause of cancer-related burden with distinct regional variations globally. Although the burden of EC has decreased, the specific reasons for this decline are still unclear.

OBJECTIVE

This study aims to uncover the spatiotemporal patterns of EC risk-attributable burden in 204 countries and territories from 1990 to 2019 so that prevention and control strategies of EC can be prioritized worldwide.

METHODS

We extracted EC risk-attributable deaths, disability-adjusted life years (DALYs), age-standardized mortality rates (ASMRs), and age-standardized DALY rates (ASDRs) from the global burden of disease (GBD) study from 1990 to 2019, in terms of behavioral, metabolic, and dietary factors by age, sex, and geographical location. Average annual percentage change (AAPC) was used to assess the long-term trends in the ASMRs and ASDRs of EC due to specific risk factors.

RESULTS

Between 1990 and 2019, the greatest decrease in EC burden was attributed to low intake of fruits and vegetables. An AAPC of -2.96 (95% CI -3.28 to -2.63) and -3.12 (95% CI -3.44 to -2.79) in ASMR and ASDR was attributable to a low-fruit diet, while an AAPC of -3.60 (95% CI -3.84 to -3.36) and -3.64 (95% CI -3.92 to -3.35) in ASMR and ASDR was attributed to a low-vegetable diet. However, the trends in ASMRs and ASDRs due to high BMI showed significant increases with an AAPC of 0.52 (95% CI 0.29-0.75) in ASMR and 0.42 (95% CI 0.18-0.66) in ASDR from 1990 to 2019 compared to significant decreases in other attributable risks with AAPC<0 (P<.05). East Asia had the largest decrease in EC burden due to low-vegetable diets, with an AAPC of -11.00 (95% CI -11.32 to -10.67) in ASMR and -11.81 (95% CI -12.21 to -11.41) in ASDR, followed by Central Asia, whereas Western Sub-Saharan Africa had the largest increase in ASMR and ASDR due to high BMI, with an AAPC of 3.28 (95% CI 3.14-3.42) and 3.09 (95% CI 2.96-3.22), respectively. China had the highest EC burden attributed to smoking, alcohol use, high BMI, and low-fruit diets. Between 1990 and 2019, there was a significant decrease in EC burden attributable to smoking, alcohol use, chewing tobacco, low-fruit diets, and low-vegetable diets in most countries, wherein a significant increase in the EC burden was due to high BMI.

CONCLUSIONS

Our study shows that smoking and alcohol consumption are still the leading risk factors of EC burden and that EC burden attributable to low intake of fruits and vegetables has shown the largest decline recently. The risks of ASMRs and ASDRs of EC showed distinct spatiotemporal patterns, and future studies should focus on the upward trend in the EC burden attributed to high BMI.

Lithium and the living kidney donor: Science or stigma?

Nearly 10 000 people are removed from the kidney transplant waiting list each year either due to becoming too ill for transplant or due to death. Live donor kidney transplant (LDKT) provides superior outcomes and survival benefit relative to deceased donor transplant, but the number of LDKT has decreased over the past few years. Therefore, it is of paramount importance that transplant centers employ evaluation processes that safely maximize LDKT. Decisions about donor candidacy should be based on the best available data, rather than on processes prone to bias. Here, we examine the common practice of declining potential donors based solely on treatment with lithium. We conclude that the risk of end-stage renal disease related to lithium treatment is comparable to other generally accepted risks in LDKT. We present this viewpoint to specifically challenge the carte blanche exclusion of individuals taking lithium and highlight the importance of using the best available data relevant to any risk factor, rather than relying on biases, when evaluating potential living kidney donors.

Corrigendum: How often is occult atrial fibrillation in cryptogenic stroke causal vs. incidental? A meta-analysis

[This corrects the article DOI: 10.3389/fneur.2023.1103664.].

Comparison of Contributors to Mortality Differences in SLE Patients with Different Initial Disease Activity: A Larger Multicenter Cohort Study

To explore the etiology of risk factors and quantify the mortality differences in systemic lupus erythematosus (SLE) patients with different initial disease activity. The Jiangsu Lupus database was established by collecting medical records from first-hospitalized SLE patients during 1999-2009 from 26 centers in Jiangsu province, China, and their survival status every five years. The initial SLEDAI scores [high (>12) vs. low-moderate (≤12)] differences in mortality attributable to risk factors were quantified using population attributable fraction (PAF), relative attributable risk (RAR) and adjusted relative risk (ARR). Among 2446 SLE patients, 83 and 176 deaths were observed in the low-moderate and high activity groups, with mortality rates of 7.7 and 14.0 per 1000 person years, respectively. Anemia was the leading contributor to mortality, with PAFs of 40.4 and 37.5 in the low-moderate and high activity groups, respectively, and explained 23.2% of the mortality differences with an ARR of 1.66 between the two groups. Cardiopulmonary involvement caused the highest PAFs in the low-moderate (20.5%) and high activity (13.6%) groups, explaining 18.3% of the mortality differences. The combination of anemia and cardiopulmonary involvement had the highest RAR, causing 39.8% of the mortality differences (ARR = 1.52) between the two groups. In addition, hypoalbuminemia and a decrease in the creatinine clearance rate accounted for 20-30% of deaths and explained 10-20% of the mortality differences between the two groups, while antimalarial drug nonuse accounted for about 35% of deaths and explained 3.6% of the mortality differences. Anemia, cardiopulmonary involvement and hypoalbuminemia may cause substantial mortality differences across disease activity states, suggesting additional strategies beyond disease activity assessment to monitor SLE outcomes.

The Impact of Ambient Temperature on Cardiorespiratory Mortality in Northern Greece

It is well-established that exposure to non-optimum temperatures adversely affects public health, with the negative impact varying with latitude, as well as various climatic and population characteristics. This work aims to assess the relationship between ambient temperature and mortality from cardiorespiratory diseases in Eastern Macedonia and Thrace, in Northern Greece. For this, a standard time-series over-dispersed Poisson regression was fit, along with a distributed lag nonlinear model (DLNM), using a maximum lag of 21 days, to capture the non-linear and delayed temperature-related effects. A U-shaped relationship was found between temperature and cardiorespiratory mortality for the overall population and various subgroups and the minimum mortality temperature was observed around the 65th percentile of the temperature distribution. Exposure to extremely high temperatures was found to put the highest risk of cardiorespiratory mortality in all cases, except for females which were found to be more sensitive to extreme cold. It is remarkable that the highest burden of temperature-related mortality was attributed to moderate temperatures and primarily to moderate cold. The elderly were found to be particularly susceptible to both cold and hot thermal stress. These results provide new evidence on the health response of the population to low and high temperatures and could be useful to local authorities and policy-makers for developing interventions and prevention strategies for reducing the adverse impact of ambient temperature.

Menopausal hormone therapy: why we should no longer be afraid of the breast cancer risk

The threat that women may develop breast cancer is the major reason why both physicians and women are afraid to use menopausal hormone therapy (MHT). The fear pertains to estrogen-progestin replacement therapy (EPRT) as estrogen-alone replacement therapy has no, or even a reduced, breast cancer risk. We reviewed the way breast cancer risk with EPRT was reported in some major publications since 2002 and tried to put the use-risk association in context. We hope this will make it easier for the physician and the menopausal woman to understand the risk involved and allow more confident and more informed decision-making regarding MHT use. We conclude that there are five interrelated reasons why physicians and women should no longer be afraid of the breast cancer risk with EPRT. We submit that breast cancer related to EPRT use is rare because the risk is very low; the reported increase in breast cancer risk with EPRT is not relevant to current practice; modifiable lifestyle factors, not EPRT, are the real risks for breast cancer; breast cancer-specific mortality is reduced in women who develop breast cancer while on EPRT; and avoiding MHT use when indicated puts a woman in harm's way.

Attributable factors for the rising cesarean delivery rate over three decades: an observational cohort study

BACKGROUND

Cesarean delivery rates continue to rise globally the reasons for which are incompletely understood.

OBJECTIVES

We aimed to characterize attributable factors for increasing cesarean delivery rates over a 30-year period within our health network.

STUDY DESIGN

This was a planned observational cohort study across two hospitals (a large tertiary referral hospital and a metropolitan hospital) in Sydney, Australia using data from a previously published study. Two time periods were compared: 1989-1999 and 2009-2016, between which the cesarean delivery rate increased from 19% to 30%. Participants were all women who had a cesarean delivery after 24 weeks gestational age. Data were analyzed using multiple imputation and robust Poisson regression to calculate differences in the adjusted and unadjusted relative risk of cesarean delivery and estimate the changes in the cesarean delivery rate attributable to maternal and clinical factors. The primary outcome was cesarean delivery.

RESULTS

After 576 exclusions, 102 589 births were included in the analysis. Fifty-six percent of the increase in the rate of cesarean delivery was attributed to changes in the distribution of maternal age, body mass index, parity and history of previous cesarean delivery. An additional 10% of the increase was attributed to changes in the obstetric management of the following high-risk pregnancies: multiple gestation, malpresentation (mainly breech) and preterm singleton birth. When pre-labor cesarean deliveries for maternal choice, suspected fetal compromise, previous pregnancy issues and suspected large fetus were excluded, 78% of the increase was attributed to either maternal factors or changes in the obstetric management of these high-risk pregnancies.

CONCLUSIONS

Most of the steep rise in the cesarean delivery rate from 19% to 30% was attributed to changes in maternal demographic and clinical factors. This observation is relevant to developing preventative strategies which account for nulliparity, age, body mass index, and the management of high-risk pregnancies.

TWEETABLE ABSTRACT

More than half of the increase in the rate of cesarean delivery is attributable to changes in maternal age, BMI, parity and history of cesarean delivery.

Synergistic Effects of Genetic Variants of Glucose Homeostasis and Lifelong Exposures to Cigarette Smoking, Female Hormones, and Dietary Fat Intake on Primary Colorectal Cancer Development in African and Hispanic/Latino American Women

BACKGROUND

Disparities in cancer genomic science exist among racial/ethnic minorities. Particularly, African American (AA) and Hispanic/Latino American (HA) women, the 2 largest minorities, are underrepresented in genetic/genome-wide studies for cancers and their risk factors. We conducted on AA and HA postmenopausal women a genomic study for insulin resistance (IR), the main biologic mechanism underlying colorectal cancer (CRC) carcinogenesis owing to obesity.

METHODS

With 780 genome-wide IR-specific single-nucleotide polymorphisms (SNPs) among 4,692 AA and 1,986 HA women, we constructed a CRC-risk prediction model. Along with these SNPs, we incorporated CRC-associated lifestyles in the model of each group and detected the topmost influential genetic and lifestyle factors. Further, we estimated the attributable risk of the topmost risk factors shared by the groups to explore potential factors that differentiate CRC risk between these groups.

RESULTS

In both groups, we detected IR-SNPs in PCSK1 (in AA) and IFT172, GCKR, and NRBP1 (in HA) and risk lifestyles, including long lifetime exposures to cigarette smoking and endogenous female hormones and daily intake of polyunsaturated fatty acids (PFA), as the topmost predictive variables for CRC risk. Combinations of those top genetic- and lifestyle-markers synergistically increased CRC risk. Of those risk factors, dietary PFA intake and long lifetime exposure to female hormones may play a key role in mediating racial disparity of CRC incidence between AA and HA women.

CONCLUSIONS

Our results may improve CRC risk prediction performance in those medically/scientifically underrepresented groups and lead to the development of genetically informed interventions for cancer prevention and therapeutic effort, thus contributing to reduced cancer disparities in those minority subpopulations.

The Mortality Effect of Apparent Temperature: A Multi-City Study in Asia

(1) Background: The health effect of temperature has become a rising public health topic. The objective of this study is to assess the association between apparent temperature and non-accidental deaths, and the mortality burden attributed to cold and heat temperature; (2) Methods: The daily data on temperature and deaths were collected from 10 cities in Thailand, Korea and China. We fitted a time-series regression with a distributed lag nonlinear model (DLNM) to derive the health risk of temperature for each city and then pooled them to get the overall cumulative risk by multivariate meta-analysis. Additionally, we calculated the attributable fraction of deaths for heat and cold, which was defined as temperatures above and below minimum-mortality temperature (MMT); (3) Results: There are regional heterogeneities in the minimum mortality percentiles (MMP) and attributable fractions for different countries. The MMP varied from about the 5-10th percentile in Thailand to 63-93rd percentile in China and Korea. The attributable fractions of the total deaths due to short-term exposure to temperature in Asia is 7.62%, of which the cold effect (6.44%) is much higher than the heat effect (1.18%); (4) Conclusions: Our study suggested that apparent temperature was associated with an increase in non-accidental mortality. Most of the temperature-related mortality burden was attributable to cold, except for Thailand.

A municipality-level analysis of excess mortality in Italy in the period January-April 2020

BACKGROUND

the first confirmed cases of COVID-19 in WHO European Region was reported at the end of January 2020 and, from that moment, the epidemic has been speeding up and rapidly spreading across Europe. The health, social, and economic consequences of the pandemic are difficult to evaluate, since there are many scientific uncertainties and unknowns.

OBJECTIVES

the main focus of this paper is on statistical methods for profiling municipalities by excess mortality, directly or indirectly caused by COVID-19.

METHODS

the use of excess mortality for all causes has been advocated as a measure of impact less vulnerable to biases. In this paper, observed mortality for all causes at municipality level in Italy in the period January-April 2020 was compared to the mortality observed in the corresponding period in the previous 5 years (2015-2019). Mortality data were made available by the Ministry of Internal Affairs Italian National Resident Population Demographic Archive and the Italian National Institute of Statistics (Istat). For each municipality, the posterior predictive distribution under a hierarchical null model was obtained. From the posterior predictive distribution, we obtained excess death counts, attributable community rates and q-values. Full Bayesian models implemented via MCMC simulations were used.

RESULTS

absolute number of excess deaths highlights the burden paid by major cities to the pandemic. The Attributable Community Rate provides a detailed picture of the spread of the pandemic among the municipalities of Lombardy, Piedmont, and Emilia-Romagna Regions. Using Q-values, it is clearly recognizable evidence of an excess of mortality from late February to April 2020 in a very geographically scattered number of municipalities. A trade-off between false discoveries and false non-discoveries shows the different values of public health actions.

CONCLUSIONS

despite the variety of approaches to calculate excess mortality, this study provides an original methodological approach to profile municipalities with excess deaths accounting for spatial and temporal uncertainty.

Factors associated with non-utilization of postnatal care among newborns in the first 2 days after birth in Pakistan: a nationwide cross-sectional study

Background

Recent data indicated that approximately four in every ten newborns in Pakistan do not receive postnatal care (PNC) services in the first 48 hours after delivery.

Objectives

This study aimed to identify factors associated with the non-utilization of PNC for newborns in Pakistan using the 2017–18 Pakistan Demographic and Health Survey (PDHS).

Methods

This was a cross-sectional analytical study utilizing data from 3887 live-born newborns recorded in the 2017–18 PDHS. Non-utilization of PNC was assessed against a set of independent factors using multilevel logistic regression analysis, and the population attributable risk estimates of factors associated with non-utilization of PNC were also calculated.

Results

There were 1443 newborns (37%) in Pakistan whose mothers did not utilize PNC check-ups in the first 2 days after delivery. The non-utilization of PNC was largely attributable to newborns delivered at non-health facilities 53% (47% to 59%) and those born to uneducated women 27% (13% to 38%). Adjusted analyses indicated that newborns with higher birth order and with a birth interval of more than 2 years, women who perceived their baby to be small at birth, women with no formal education and those living in regional areas of Khyber Pakhtunkhwa and Federally Administered Tribal Areas were significantly associated with non-utilization of PNC services.

Conclusions

Tailored health messages by community health workers, including door-to-door visits on utilizing health facilities through pregnancy to the postnatal periods, are needed and should target places of low socioeconomic status, including educationally disadvantaged women from regional areas of Pakistan.

Incidence and outcomes of dengue in a cohort of pregnant women from an endemic region of India: obesity could be a potential risk for adverse outcomes

BACKGROUND

The primary objectives of the study were to determine the incidence of dengue and outcomes associated with dengue among pregnant women.

METHODS

A prospective cohort study was done among 1579 antenatal women in an endemic region in India. Dengue immunoglobulin G (IgG) was tested in 490 women at baseline. Follow-up phone calls and visits were done until 1 week after delivery. In 70 seronegative women, dengue IgG was repeated to identify seroconversion. Incidence proportions, incidence rates, relative risks, attributable risks and population attributable risks along with their 95% confidence intervals (CIs) were calculated. Propensity score methods were used for multivariate assessment of confounding and analysis was repeated with a matched dataset.

RESULTS

The seroprevalence of dengue was 30.41% (95% CI 26.45 to 34.59). NS1 positivity detected 78% of dengue in pregnancy. There were no abortions or maternal or newborn deaths. Dengue was significantly associated with delivery complications (adjusted odds ratio [OR] 10.28 [95% CI 4.79 to 22.01]), newborn problems (adjusted OR 5.29 [95% CI 2.89 to 9.70]) and newborn admissions (adjusted OR 5.24 [95% CI 2.36 to 11.65]). Overweight dengue patients had a significantly higher risk of preterm deliveries and higher adverse outcome scores.

CONCLUSIONS

Screening of febrile antenatal women for dengue in endemic areas can result in early diagnosis and reduce complications. The dual burden of communicable and non-communicable diseases in pregnancy is a real challenge.

Attributable Mortality of Hip Fracture in Older Patients: A Retrospective Observational Study

Hip fracture (HF) in older patients is associated with a high six-month mortality rate. Several clinical conditions may affect outcome, including baseline characteristics, co-existing acute illnesses, perioperative factors, and postoperative complications. Our primary objective was to estimate the respective effect of these four domains on six-month mortality after HF. A retrospective observational study using a monocentric cohort of older patients was conducted. All patients ≥ 70 years old admitted to the emergency department for HF and hospitalized in our perioperative geriatric care unit from June 2009 to September 2018 were included. Among 1015 included patients, five (0.5%) were lost to follow-up, and 1010 were retained in the final analysis (mean age 86 ± 6 years). The six-month mortality rate was 14.8%. The six-month attributable mortality estimates were as follows: baseline characteristics (including age, gender, comorbidities, autonomy, type of fracture): 62.4%; co-existing acute illnesses (including acute events present before surgery that could result from the fracture or cause it): 0% (not significantly associated with six-month mortality); perioperative factors (including blood transfusion and delayed surgery): 12.3%; severe postoperative complications: 11.9%. Baseline characteristics explained less than two-thirds of the six-month mortality after HF. Optimizing patients care by improving management of perioperative factors and thus decreasing postoperative complications, could reduce by a maximum of one quarter of the six-month mortality rate after HF.

Attributable Risk to Assess the Health Impact of Air Pollution: Advances, Controversies, State of the Art and Future Needs

Despite the increased attention given to the health impact assessment of air pollution and to the strategies to control it in both scientific literature and concrete interventions, the results of the implementations, especially those involving traffic, have not always been satisfactory and there is still disagreement about the most appropriate interventions and the methods to assess their effectiveness. This state-of-the-art article reviews the recent interpretation of the concepts that concern the impact assessment, and compares old and new measurements of attributable risk and attributable fraction. It also summarizes the ongoing discussion about the designs and methods for assessing the air pollution impact with particular attention to improvements due to spatio-temporal analysis and other new approaches, such as studying short term effects in cohorts, and the still discussed methods of predicting the values of attributable risk (AR). Finally, the study presents the more recent analytic perspectives and the methods for directly assessing the effects of not yet implemented interventions on air quality and health, in accordance with the suggestion in the strategic plan 2020-2025 from the Health Effect Institute.

Underlying Breast Cancer Risk and Menopausal Hormone Therapy

The recent Collaborative Group on Hormonal Factors in Breast Cancer (CGHFBC) publication calculated the attributable risk of breast cancer from use of estrogen alone and estrogen plus a synthetic progestogen for less than 5 to 15 or more years of use. This CGHFB report calculated attributable risk based on their findings of relative risk from pooled data from 58 studies. Notably, neither the CGHFBC nor other previous studies have examined the effect of underlying risk of breast cancer on attributable risk. This omission prompted us to determine the magnitude of the effect of underlying risk on attributable risk in this perspective. Meaningful communication of the potential risk of menopausal hormonal therapy requires providing women with the estimated risk above their existing underlying risk (ie, attributable risk). Therefore, we have estimated attributable risks from the data published by the CGHFBC, taking into account varying degrees of underlying risk. Based on the Endocrine Society Guideline on Menopausal Hormone Therapy (MHT), we divided groups into 3 categories of risk: low (1.5%), intermediate (3.0%), and high (6.0%) underlying risk of breast cancer over 5 years. In women taking estrogen plus a synthetic progestogen for 5 to 9 years, the attributable risks of MHT increased from 12, to 42, to 85 additional women per 1000 in the low-, intermediate-, and high-risk groups, respectively. The attributable risks for estrogen alone were lower but also increased based on underlying risk. Notably, the attributable risks were amplified with duration of MHT use, which increased both relative risk and breast cancer incidence.

Quantifying degrees of necessity and of sufficiency in cause-effect relationships with dichotomous and survival outcomes

We suggest measures to quantify the degrees of necessity and of sufficiency of prognostic factors for dichotomous and for survival outcomes. A cause, represented by certain values of prognostic factors, is considered necessary for an event if, without the cause, the event cannot develop. It is considered sufficient for an event if the event is unavoidable in the presence of the cause. Necessity and sufficiency can be seen as the two faces of causation, and this symmetry and equal relevance are reflected by the suggested measures. The measures provide an approximate, in some cases an exact, multiplicative decomposition of explained variation as defined by Schemper and Henderson for censored survival and for dichotomous outcomes.

The measures, ranging from zero to one, are simple, intuitive functions of unconditional and conditional probabilities of an event such as disease or death. These probabilities often will be derived from logistic or Cox regression models; the measures, however, do not require any particular model.

The measures of the degree of necessity implicitly generalize the established attributable fraction or risk for dichotomous prognostic factors and dichotomous outcomes to continuous prognostic factors and to survival outcomes. In a setting with multiple prognostic factors, they provide marginal and partial results akin to marginal and partial odds and hazard ratios from multiple logistic and Cox regression.

Properties of the measures are explored by an extensive simulation study. Their application is demonstrated by three typical real data examples.

The population-attributable fraction for time-dependent exposures using dynamic prediction and landmarking

The public health impact of a harmful exposure can be quantified by the population-attributable fraction (PAF). The PAF describes the attributable risk due to an exposure and is often interpreted as the proportion of preventable cases if the exposure was extinct. Difficulties in the definition and interpretation of the PAF arise when the exposure of interest depends on time. Then, the definition of exposed and unexposed individuals is not straightforward. We propose dynamic prediction and landmarking to define and estimate a PAF in this data situation. Two estimands are discussed which are based on two hypothetical interventions that could prevent the exposure in different ways. Considering the first estimand, at each landmark the estimation problem is reduced to a time-independent setting. Then, estimation is simply performed by using a generalized-linear model accounting for the current exposure state and further (time-varying) covariates. The second estimand is based on counterfactual outcomes, estimation can be performed using pseudo-values or inverse-probability weights. The approach is explored in a simulation study and applied on two data examples. First, we study a large French database of intensive care unit patients to estimate the population-benefit of a pathogen-specific intervention that could prevent ventilator-associated pneumonia caused by the pathogen Pseudomonas aeruginosa. Moreover, we quantify the population-attributable burden of locoregional and distant recurrence in breast cancer patients.

Antenatal Risk Scoring Scale for Predication of Low Birth Weight and Its Validity

BACKGROUND

Prediction of low birth weight (LBW) early during pregnancy may prevent LBW by appropriate interventions.

AIMS/OBJECTIVE

The aim of the study is to develop an antenatal risk scoring scale for prediction of LBW.

SUBJECT AND METHODS

Routine and in-depth information on diet, occupation, and rest was collected from November 1, 2013, to November 13, 2015. A cohort of 1876 and subset of 380 pregnant women attending Krishna Hospital Karad, Maharashtra, India.

STATISTICAL ANALYSIS

Multivariate analysis and relative risks (RRs) were found out by SPSS version 16 and tested on a separate set of 251 mothers.

RESULTS

The frequency of meals of <4, hard work <6 h of sleep and illiteracy, antenatal morbidity, <10 kg weight gain, <40 kg maternal weight, and anemia during the first trimester were the risk factors identified from subset and cohort, respectively. Based on their RRs, a new scoring system with a total score of 24 and cutoff "12" was identified by using receiver operating characteristics (ROC) curve analysis with 98.6% sensitivity and 41.1% specificity as tested on 251-independent individuals. The second cutoff of "15" score was identified based on the prevalence of LBW in babies of these 251 mothers.

CONCLUSIONS

The identification of low-, moderate-, and high-risk of LBW was possible at <12, between 12 and 15, and >15 scores, respectively, with good sensitivity and specificity.

Development of Risk Scoring Scale Tool for Prediction of Preterm Birth

BACKGROUND

Prediction of preterm births in the early stage during pregnancy may reduce prevalence of preterm births by appropriate interventions.

AIMS/OBJECTIVE

The aim of the study is to develop an antenatal risk scoring system/scale for prediction of preterm births.

SUBJECTS AND METHODS

From a cohort of 1876 and subset of 380 pregnant women attending Krishna Hospital Karad, Maharashtra, routine antenatal and in-depth information on diet, occupation, and the rest were collected and analyzed using SPSS version 16. A scoring system was developed by multivariate analysis based on the relative risk (RR) and tested on separate set of 251 mothers.

STATISTICAL ANALYSIS USED

Bivariate analysis by Chi-square test, backward multivariate regression model, receiver operating characteristic curve (ROC) curve analysis, and calculation of RR for identified risk factors. Sensitivity and specificity of newly developed risk scoring scale.

RESULTS

Out of six risk factors from whole cohort (n = 1876) and three risk factors from subsample (n = 380) identified by bivariate analysis. Further four and three risk factors were retained after multivariate analysis from whole and part of cohort, respectively, and risk scores of "7" and "9" were assigned based on RR cutoff levels of three and five were identified separately for whole and part data by ROC curve analyses together making it "8" with 75.5% sensitivity and 85.5% specificity when tested on 251 independent patients. Based on the prevalence of preterm births, low-, moderate-, and high-risk grading was done by identifying as second cutoff value.

CONCLUSIONS

Identification of low-, moderate-, and high-risk of preterm births was possible at <8, 8, and 9 and equal to ≥10 with high sensitivity at lower cutoff and high specificity at upper cutoff.

Frequency of frontotemporal dementia gene variants in C9ORF72, MAPT, and GRN in academic versus commercial laboratory cohorts

Background

Frontotemporal lobar degeneration (FTLD) is a leading cause of dementia, and elucidating its genetic underpinnings is critical. FTLD research centers typically recruit patient cohorts that are limited by the center's specialty and the ways in which its geographic location affects the ethnic makeup of research participants. Novel sources of data are needed to get population estimates of the contribution of variants in known FTLD-associated genes.

Methods

We compared FLTD-associated genetic variants in microtubule-associated protein tau (MAPT), progranulin (GRN), and chromosome nine open reading frame 72 (C9ORF72) from an academic research cohort and a commercial clinical genetics laboratory. Pathogenicity was assessed using guidelines of the American College of Medical Genetics and Genomics and a rule-based DNA variant assessment system. We conducted chart reviews on patients with novel or rare disease-associated variants.

Results

A total of 387 cases with FTLD-associated variants from the commercial (n=2,082) and 78 cases from the academic cohort (n=2,089) were included for analysis. In the academic cohort, the most frequent pathogenic variants were C9ORF72 expansions (63%, n=49), followed by GRN (26%, n=20) and MAPT (11%, n=9). Each gene's contribution to disease was similarly ranked in the commercial laboratory but differed in magnitude: C9ORF72 (89%, n=345), GRN (6%, n=24), and MAPT (5%, n=19). Of the 37 unique GRN/MAPT variants identified, only six were found in both cohorts. Clinicopathological data from patients in the academic cohort strengthened classification of two novel GRN variant as pathogenic (p.Pro166Leufs*2, p.Gln406*) and one GRN variant of unknown significance as a possible rare risk variant (p.Cys139Arg).

Conclusion

Differences in gene frequencies and identification of unique pathogenic alleles in each cohort demonstrate the importance of data sharing between academia and community laboratories. Using shared data sources with well-characterized clinical phenotypes for individual variants can enhance interpretation of variant pathogenicity and inform clinical management of at-risk patients and families.

Static metrics of impact for a dynamic problem: The need for smarter tools to guide suicide prevention planning and investment

OBJECTIVES

This study investigates two approaches to estimate the potential impact of a population-level intervention on Australian suicide, to highlight the importance of selecting appropriate analytic approaches for informing evidence-based strategies for suicide prevention.

METHODS

The potential impact of a psychosocial therapy intervention on the incidence of suicide in Australia over the next 10 years was used as a case study to compare the potential impact on suicides averted using: (1) a traditional epidemiological measure of population attributable risk and (2) a dynamic measure of population impact based on a systems science model of suicide that incorporates changes over time.

RESULTS

Based on the population preventive fraction, findings suggest that the psychosocial therapy intervention if implemented among all eligible individuals in the Australian population would prevent 5.4% of suicides (or 1936 suicides) over the next 10 years. In comparison, estimates from the dynamic simulation model which accounts for changes in the effect size of the intervention over time, the time taken for the intervention to have an impact in the population, and likely barriers to the uptake and availability of services suggest that the intervention would avert a lower proportion of suicides (between 0.4% and 0.5%) over the same follow-up period.

CONCLUSION

Traditional epidemiological measures used to estimate population health burden have several limitations that are often understated and can lead to unrealistic expectations of the potential impact of evidence-based interventions in real-world settings. This study highlights these limitations and proposes an alternative analytic approach to guide policy and practice decisions to achieve reductions in Australian suicide.

Estimating the drink driving attributable fraction of road traffic deaths in Mexico

AIM

To estimate the Drink Driving Attributable Fraction (DDAF) of road traffic injury mortality in car occupants in Mexico during 2010-13.

DESIGN

A case-control study was conducted to examine the presence of alcohol in analysed body fluids of car occupants killed in fatal crashes (cases) compared with car drivers tested in alcohol-testing checkpoints who were not involved in a fatal collision (controls). Two data sets were used for the period 2010-13: the forensic module of the Epidemiological Surveillance System on Addictions that included car occupants killed in a collision (cases) and a data set from alcohol-testing at police checkpoints available for matching municipalities (controls).

SETTING

Mexico.

PARTICIPANTS

The analysed study sample included 1718 car occupants killed in a traffic collision and 80 656 drivers tested at alcohol police checkpoints, all from 10 municipalities.

MEASUREMENTS

Unadjusted and adjusted odds ratios (OR) of presence of alcohol in body fluids were obtained stratified by sex and age groups and the interaction with these two variables were assessed. The ORs were used to calculate the DDAF.

FINDINGS

It was estimated that 19.5% of car occupants' deaths due to road traffic injuries were attributable to alcohol consumption [95% confidence interval (CI) = 19.1-19.9]. The adjusted OR of presence of alcohol was 6.84 (95% CI = 6.06-7.71) overall. For males it was 7.21 (95% CI = 6.35-8.18) and for females it was 4.45 (95% CI = 3.01-6.60). The ORs were similar across younger age bands (10-19 years: 9.61, 95% CI = 6.72-13.73; 20-29 years: 7.70, 95% CI = 6.28-9.4; and 30-49 years: 7.21, 95% CI = 5.98-8.70); and lower but still elevated among older people (50+ years: 3.19, 95% CI = 2.19-4.65).

CONCLUSIONS

An estimated 19.5% of car occupant deaths in Mexico may have been caused by alcohol in 2010-13.

Incidence and risk of chronic obstructive pulmonary disease in a Korean community-based cohort

Purpose

COPD is a leading cause of morbidity and mortality. However, few studies have used spirometry to investigate its incidence, especially in Asia. In the present study, we analyzed the incidence and risk factors of COPD using a community cohort database in Korea.

Patients and methods

The study included 6,517 subjects aged 40–69 years from the Ansung–Ansan cohort database I–III (2001–2006). We calculated the crude incidence rate and the standardized incidence rate corrected for the Korean general population and the world population with COPD. We also determined the relative risks (RRs) for incident COPD and the attributable risks.

Results

In total, 329 new COPD cases were diagnosed during follow-up. The overall crude incidence rate per 100,000 person-years was 1,447. The standardized incidence rate corrected for the Korean general population was 1,550; this value was higher in men and increased with increasing age. Risk factors for incident COPD were age ≥60 years (adjusted RR [aRR] =2.52 vs age <60 years), male sex (aRR =2.02 vs female), heavy smoking (≥20 pack-years; aRR =2.54 vs never smoker), and lowest income group (first quartile; aRR =2.03 vs fourth quartile). The adjusted attributable risk was highest for education level of high school or lower (44.9%), followed by smoking history (25.8%), income (22.9%), and sex (12.0%).

Conclusion

In Korea, 15.5/1,000 people are diagnosed with COPD annually. The incidence rate increases with increasing age, heavier smoking, and decreasing income, with a higher rate in men than in women.

The effect of risk factor misclassification on the partial population attributable risk

The partial population attributable risk (pPAR) is used to quantify the population-level impact of preventive interventions in a multifactorial disease setting. In this paper, we consider the effect of nondifferential risk factor misclassification on the direction and magnitude of bias of pPAR estimands and related quantities. We found that the bias in the uncorrected pPAR depends nonlinearly and nonmonotonically on the sensitivities, specificities, relative risks, and joint prevalence of the exposure of interest and background risk factors, as well as the associations between these factors. The bias in the uncorrected pPAR is most dependent on the sensitivity of the exposure. The magnitude of bias varies over a large range, and in a small region of the parameter space determining the pPAR, the direction of bias is away from the null. In contrast, the crude PAR can only be unbiased or biased towards the null by risk factor misclassification. The semiadjusted PAR is calculated using the formula for the crude PAR but plugs in the multivariate-adjusted relative risk. Because the crude and semiadjusted PARs continue to be used in public health research, we also investigated the magnitude and direction of the bias that may arise when using these formulae instead of the pPAR. These PAR estimators and their uncorrected counterparts were calculated in a study of risk factors for colorectal cancer in the Health Professionals Follow-up Study, where it was found that because of misclassification, the pPAR for low folate intake was overestimated with a relative bias of 48%, when red meat and alcohol intake were treated as misclassified risk factors that are not modified, and when red meat was treated as the modifiable risk factor, the estimated value of the pPAR went from 14% to 60%, further illustrating the extent to which misclassification can bias estimates of the pPAR.

Infant morbidity and mortality attributable to prenatal smoking in Chile

OBJECTIVE

To estimate annual infant morbidity and mortality attributable to prenatal smoking in Chile during 2008-2012.

METHODS

Population-attributable fractions (PAFs) for several infant outcomes were calculated based on previous study estimates of prenatal smoking prevalence and odds ratios associated with exposure (prenatal smoking relative to non-prenatal smoking). Prenatal smoking-attributable infant morbidity and mortality cases were calculated by multiplying the average annual number of morbidity and mortality cases registered in Chile during 2008-2012 by the corresponding PAF.

RESULTS

PAFs for 1) births ≤ 27 weeks; 2) births at 28-33 weeks; 3) births at 34-36 weeks; and 4) full-term low-birth-weight infants were 12.3%, 10.6%, 5.5%, and 27.4% respectively. PAFs for deaths caused by preterm-related causes and deaths caused by sudden infant death syndrome were 11.9% and 40.0% respectively. Annually, 2 054 cases of preterm-birth and full-term low-birth-weight (1 in 9 cases), 68 deaths caused by preterm-related causes (1 in 8 cases), and 26 deaths caused by sudden infant death syndrome (1 in 3 cases) were attributable to prenatal smoking.

CONCLUSIONS

In Chile, infant morbidity and mortality attributable to prenatal smoking are unacceptably high. Comprehensive individual and population-based interventions for tobacco control should be a public health priority in the country, particularly among female adolescents and young women who will be the mothers of future generations.

Biostatistics Series Module 8: Assessing Risk

In observational studies, as well as in interventional ones, it is frequently necessary to estimate risk that is the association between an observed outcome or event and exposure to one or more factors that may be contributing to the event. Understanding incidence and prevalence are the starting point in any discussion of risk assessment. Incidence rate uses person-time as the denominator rather than a simple count. Ideally, rates and ratios estimated from samples should be presented with their corresponding 95% confidence intervals (CIs). To assess the importance of an individual risk factor, it is necessary to compare the risk of the outcome in the exposed group with that in the nonexposed group. A comparison between risks in different groups can be made by examining either their ratio or the difference between them. The 2 × 2 contingency table comes in handy in the calculation of ratios. Odds ratio (OR) is the ratio of the odds of an event in the exposed group, to the odds of the same event in the nonexposed group. It can range from zero to infinity. When the odds of an outcome in the two groups are identical, then the OR equals one. OR >1 indicates exposure increases risk while OR <1 indicates that exposure is protecting against risk. The OR should be presented with its 95% CI to enable more meaningful interpretation – if this interval includes 1, then even a relatively large OR will not carry much weight. The relative risk (RR) denotes the ratio of risk (probability) of event in exposed group to risk of same event in the nonexposed group. Its interpretation is similar (but not identical) to the OR. If the event in question is relatively uncommon, values of OR and RR tend to be similar. Absolute risk reduction (ARR) is a measure of the effectiveness of an intervention with respect to a dichotomous event. It is calculated as proportion experiencing the event in control group minus the proportion experiencing the event in treated group. It is often used to denote the benefit to the individual. The reciprocal of ARR is the number needed to treat (NNT), and it denotes the number of subjects who would need to be treated to obtain one more success than that obtained with a control treatment. Alternatively, this could also denote the number that would need to be treated to prevent one additional adverse outcome as compared to control treatment. Extended to toxicity, the NNT becomes a measure of harm and is then known as the number needed to harm (NNH). NNT and NNH are important concepts from the policy makers perspective and ideally should be calculated in all trials of therapeutic or prophylactic intervention.

Pneumonia Hospitalization Risk in the Elderly Attributable to Cold and Hot Temperatures in Hong Kong, China

The growth of pathogens potentially relevant to respiratory tract infection may be triggered by changes in ambient temperature. Few studies have examined the association between ambient temperature and pneumonia incidence, and no studies have focused on the susceptible elderly population. We aimed to examine the short-term association between ambient temperature and geriatric pneumonia and to assess the disease burden attributable to cold and hot temperatures in Hong Kong, China. Daily time-series data on emergency hospital admissions for geriatric pneumonia, mean temperature, relative humidity, and air pollution concentrations between January 2005 and December 2012 were collected. Distributed-lag nonlinear modeling integrated in quasi-Poisson regression was used to examine the exposure-lag-response relationship between temperature and pneumonia hospitalization. Measures of the risk attributable to nonoptimal temperature were calculated to summarize the disease burden. Subgroup analyses were conducted to examine the sex difference. We observed significant nonlinear and delayed associations of both cold and hot temperatures with pneumonia in the elderly, with cold temperatures having stronger effect estimates. Among the 10.7% of temperature-related pneumonia hospitalizations, 8.7% and 2.0% were attributed to cold and hot temperatures, respectively. Most of the temperature-related burden for pneumonia hospitalizations in Hong Kong was attributable to cold temperatures, and elderly men had greater susceptibility.

The Burden of Cardiovascular Disease Attributable to Major Modifiable Risk Factors in Indonesia

BACKGROUND

In Indonesia, coronary heart disease (CHD) and stroke are estimated to cause more than 470 000 deaths annually. In order to inform primary prevention policies, we estimated the sex- and age-specific burden of CHD and stroke attributable to five major and modifiable vascular risk factors: cigarette smoking, hypertension, diabetes, elevated total cholesterol, and excess body weight.

METHODS

Population attributable risks for CHD and stroke attributable to these risk factors individually were calculated using summary statistics obtained for prevalence of each risk factor specific to sex and to two age categories (<55 and ≥55 years) from a national survey in Indonesia. Age- and sex-specific relative risks for CHD and stroke associated with each of the five risk factors were derived from prospective data from the Asia-Pacific region.

RESULTS

Hypertension was the leading vascular risk factor, explaining 20%-25% of all CHD and 36%-42% of all strokes in both sexes and approximately one-third of all CHD and half of all strokes across younger and older age groups alike. Smoking in men explained a substantial proportion of vascular events (25% of CHD and 17% of strokes). However, given that these risk factors are likely to be strongly correlated, these population attributable risk proportions are likely to be overestimates and require verification from future studies that are able to take into account correlation between risk factors.

CONCLUSIONS

Implementation of effective population-based prevention strategies aimed at reducing levels of major cardiovascular risk factors, especially blood pressure, total cholesterol, and smoking prevalence among men, could reduce the growing burden of CVD in the Indonesian population.

Population attributable fraction: planning of diseases prevention actions in Brazil

Epidemiology is the study of occurrence, distribution and determinants of health-related events, including the application of that knowledge to the prevention and control of health problems. However, epidemiological studies, in most cases, have limited their research questions to determinants of health outcomes. Research related to the application of knowledge for prevention and control of diseases have been neglected. In this comment, we present a description of how population attributable fraction estimates can provide important elements for planning of prevention and control of diseases in Brazil. RESUMO Epidemiologia é o estudo da ocorrência, distribuição e determinantes de eventos relacionados à saúde da população, incluindo a aplicação desse conhecimento para a prevenção e o controle dos problemas de saúde. Entretanto, estudos epidemiológicos, na maioria das vezes, têm limitado suas perguntas de pesquisa aos fatores determinantes de desfechos em saúde. Pesquisas relacionadas à aplicação do conhecimento para ações de prevenção e controle de doenças têm sido negligenciadas. Nesse comentário, apresentamos uma descrição de como as estimativas de fração atribuível populacional podem fornecer importantes elementos para planejamento de ações de prevenção e controle de doenças no Brasil.

A case-control study of airways obstruction among construction workers

BACKGROUND

While smoking is the major cause of chronic obstructive pulmonary disease (COPD), occupational exposures to vapors, gases, dusts, and fumes (VGDF) increase COPD risk. This case-control study estimated the risk of COPD attributable to occupational exposures among construction workers.

METHODS

The study population included 834 cases and 1243 controls participating in a national medical screening program for older construction workers between 1997 and 2013. Qualitative exposure indices were developed based on lifetime work and exposure histories.

RESULTS

Approximately 18% (95% CI = 2-24%) of COPD risk can be attributed to construction-related exposures, which are additive to the risk contributed by smoking. A measure of all VGDF exposures combined was a strong predictor of COPD risk.

CONCLUSIONS

Construction workers are at increased risk of COPD as a result of broad and complex effects of many exposures acting independently or interactively. Control methods should be implemented to prevent worker exposures, and smoking cessation should be promoted.

How many preterm births in England are due to excision of the cervical transformation zone? Nested case control study

BACKGROUND

Preterm births (as a proportion of all births) have been increasing in many countries. There is growing evidence of increased risk of preterm birth following excisional treatment of the cervix. We estimate the number of preterm births attributable to excisional treatments with a length of 10 mm or more in England.

METHODS

Case-control study nested in a record linkage cohort of women with a histological sample at 13 hospitals in England. We combined observed age at first excisional treatment in our cohort with the weighted distribution of excision length from the case-control study to estimate the length distribution by age at first treatment among the cohort. The number of births after excision for each 5-year age group was estimated using national fertility data; published absolute risks of preterm (<37 gestational weeks) and very preterm birth (<32 weeks) were applied to these to estimate the number of preterm births per 100 women treated. Excess preterm births were estimated assuming all treatments were small. The attributable risk of preterm birth following excisional treatment in England was estimated.

RESULTS

The majority of first excisional treatments at colposcopy were small (47.5%) or medium (39.1%), 9.5% were large and 4.1% were very large excisions. 4.0% of women treated before birth had more than one excisional treatment. Thus based on our cohort of 10,711 treated women and the length of treatment observed in the case control study we estimate an excess of 240 preterm births (including 57 very preterm) or 2.2 (including 0.5 very preterm) per 100 women treated. At a population level (for England) we estimate that 39,101 women aged 20-39 would be treated each year and that these treatments will lead to an excess of 840 preterm births (including 196 very preterm) in England each year.

CONCLUSIONS

Assuming associations between preterm birth and treatment for cervical disease are causal; we estimate that an excess 840 (2.5%) preterm birth in England each year are due to excisional treatments of 10 mm or more. Those that go on to become pregnant should be closely monitored during antenatal period to reduce their risk of preterm birth.

Multiple Interacting Risk Factors: On Methods for Allocating Risk Factor Interactions

A persistent problem in health risk analysis where it is known that a disease may occur as a consequence of multiple risk factors with interactions is allocating the total risk of the disease among the individual risk factors. This problem, referred to here as risk apportionment, arises in various venues, including: (i) public health management, (ii) government programs for compensating injured individuals, and (iii) litigation. Two methods have been described in the risk analysis and epidemiology literature for allocating total risk among individual risk factors. One method uses weights to allocate interactions among the individual risk factors. The other method is based on risk accounting axioms and finding an optimal and unique allocation that satisfies the axioms using a procedure borrowed from game theory. Where relative risk or attributable risk is the risk measure, we find that the game-theory-determined allocation is the same as the allocation where risk factor interactions are apportioned to individual risk factors using equal weights. Therefore, the apportionment problem becomes one of selecting a meaningful set of weights for allocating interactions among the individual risk factors. Equal weights and weights proportional to the risks of the individual risk factors are discussed.

Smoking and mortality in a prospective cohort study of elderly Chinese in Hong Kong

BACKGROUND AND AIMS

Large cohort studies on smoking and mortality in elderly people are scarce, and few studies examined smokers aged 85+ years separately. We estimated the risks of all-cause and cause-specific mortality due to smoking in an elderly Chinese cohort in Hong Kong.

DESIGN

A population-based prospective cohort of 65,510 Chinese enrolled from 1998 to 2001 and followed until May 2012.

SETTING

All 18 Elderly Health Service centres in Hong Kong, China.

PARTICIPANTS

Elderly people aged 65+ years.

MEASUREMENTS

Self-reported smoking status was assessed at baseline interview and categorized as never, former and current smokers.

FINDINGS

Compared with never smokers, after adjustment for sex, age, education, social security assistance, housing type, monthly expenditure, alcohol use, depressive symptoms and health status, the hazard ratio (HR) for current smokers was 1.89 [95% confidence interval (CI) = 1.81-1.98] for all participants aged 65+ years at baseline, corresponding to an attributable fraction (AF) of about 50%, which is based on AF = (HR-1)/HR. As the effect of smoking varied with age (P for age interaction <0.001), subgroup analysis by age group showed that the adjusted HR for current smokers aged 65-84 years was 1.93 (95% CI = 1.84-2.03), and for 85+ years was 1.29 (95% CI = 1.05-1.58). All the risk estimates did not vary by sex (P for sex interaction ranged 0.74-0.89).

CONCLUSIONS

In Hong Kong, the risk of death from smoking appears to be the same for Chinese women as it is for men. Half of all deaths in Chinese smokers aged 65 years and older and a quarter of all deaths in Chinese smokers aged 85 years and older are caused by smoking-attributable diseases.

Population attributable risks of hypertension and diabetes for cardiovascular disease and stroke in the northern Manhattan study

BACKGROUND

Understanding the population-level risk factor contribution to disease incidence is critical for effective allocation of resources for prevention. There are little data on the contribution of cardiovascular disease (CVD) risk factors in multiethnic elderly populations.

METHODS AND RESULTS

The Northern Manhattan Study (n=3298) is a population-based prospective cohort study of CVD outcomes in a multiethnic urban population. Multivariable Cox's models were used to calculate hazard ratios, population attributable risk (PAR), and 95% confidence intervals (CIs) for (1) combined vascular event (VE) endpoint of stroke/myocardial infarction/vascular death (n=835) and (2) stroke (n=347). The PAR resulting from hypertension (HTN) was 24.3% (95% CI, 13.2 to 35.4) for VE and 29.9% (95% CI, 12.5 to 47.4) for stroke; PAR resulting from diabetes was 12.7% (95% CI, 8.2 to 17.2) for VE and 19.5% (95% CI, 12.4 to 26.5) for stroke. The PAR resulting from HTN and diabetes for stroke differed by race-ethnicity and age (P for differences <0.05). PAR for stroke reslting from HTN was greater among Hispanics (50.6%; 95% CI, 29.2 to 71.9) than non-Hispanic whites (2.6%; 95% CI, -33.2 to 38.6) and in those <80 years of age (35.6%; 95% CI, 18.9 to 52.3) than in those ≥80 (-0.3%; 95% CI, -34.2 to 33.6). Similarly, the PAR for stroke resulting from diabetes was 23.6% among those <80 years of age (95% CI, 15.7 to 31.5) and 2.3% among those ≥80 (95% CI, -8.2 to 12.7; P for difference=0.001). The PAR for VE did not differ by age/sex/race-ethnicity.

CONCLUSIONS

HTN and diabetes have important effects on the burden of stroke, particularly among those younger than age 80 and Hispanics. Public health campaigns targeted at specific risk factors in specific populations can lead to a greater reduction in CVD.

Estimating Risk with Time-to-Event Data: An Application to the Women's Health Initiative

Accurate and individualized risk prediction is critical for population control of chronic diseases such as cancer and cardiovascular disease. Large cohort studies provide valuable resources for building risk prediction models, as the risk factors are collected at the baseline and subjects are followed over time until disease occurrence or termination of the study. However, for rare diseases the baseline risk may not be estimated reliably based on cohort data only, due to sparse events. In this paper, we propose to make use of external information to improve efficiency for estimating time-dependent absolute risk. We derive the relationship between external disease incidence rates and the baseline risk, and incorporate the external disease incidence information into estimation of absolute risks, while allowing for potential difference of disease incidence rates between cohort and external sources. The asymptotic properties, namely, uniform consistency and weak convergence, of the proposed estimators are established. Simulation results show that the proposed estimator for absolute risk is more efficient than that based on the Breslow estimator, which does not utilize external disease incidence rates. A large cohort study, the Women's Health Initiative Observational Study, is used to illustrate the proposed method.

Assessing Risks to Sea Otters and the Exxon Valdez Oil Spill: New Scenarios, Attributable Risk, and Recovery

The Exxon Valdez oil spill occurred more than two decades ago, and the Prince William Sound ecosystem has essentially recovered. Nevertheless, discussion continues on whether or not localized effects persist on sea otters (Enhydra lutris) at northern Knight Island (NKI) and, if so, what are the associated attributable risks. A recent study estimated new rates of sea otter encounters with subsurface oil residues (SSOR) from the oil spill. We previously demonstrated that a potential pathway existed for exposures to polycyclic aromatic hydrocarbons (PAHs) and conducted a quantitative ecological risk assessment using an individual-based model that simulated this and other plausible exposure pathways. Here we quantitatively update the potential for this exposure pathway to constitute an ongoing risk to sea otters using the new estimates of SSOR encounters. Our conservative model predicted that the assimilated doses of PAHs to the 1-in-1000th most-exposed sea otters would remain 1-2 orders of magnitude below the chronic effects thresholds. We re-examine the baseline estimates, post-spill surveys, recovery status, and attributable risks for this subpopulation. We conclude that the new estimated frequencies of encountering SSOR do not constitute a plausible risk for sea otters at NKI and these sea otters have fully recovered from the oil spill.

Hospital admissions in relation to body mass index in UK women: a prospective cohort study

BACKGROUND

Adiposity is associated with many adverse health outcomes but little direct evidence exists about its impact on the use of health care services. We aim to describe the relationship between body mass index (BMI) and rates of hospital admission in middle-aged UK women.

METHODS

Among 1,251,619 Million Women Study participants, 50- to 64-years old at entry into the study, routine data on hospital admissions were used to estimate hospitalization rates according to BMI after standardization for age, region of recruitment, socioeconomic status, reproductive history, smoking status, hormonal therapy use and alcohol intake. Proportional hazards models were used to estimate adjusted relative risks of hospitalization separately for 25 common types of admission.

RESULTS

During an average of 9.2 years follow-up, there were 2,834,016 incident hospital admissions. In women with BMIs (in kg/m2) of <22.5, 22.5 to <25, 25 to <30, 30 to <35 and 35+ standardized admission rates (and 95% confidence intervals (CIs)) per woman over a 10-year period were 2.4 (2.4 to 2.4), 2.4 (2.3 to 2.4), 2.6 (2.6 to 2.6), 3.0 (3.0 to 3.0) and 3.5 (3.4 to 3.5), respectively (P-value for heterogeneity <0.001). The relative increase in admission rates per 5 kg/m2 increase in BMI was 1.12 (1.12 to 1.13). This relationship did not vary materially by age. Corresponding average durations of stay (in days) per hospital visit within the same categories of BMI were: 3.1 (3.1 to 3.2), 2.8 (2.7 to 2.8), 2.9 (2.9 to 2.9), 3.2 (3.1 to 3.2) and 3.8 (3.7 to 3.8), respectively (P <0.001).Significant increases in the risk of admission with increasing BMI were observed for 19 of the 25 types of hospital admission considered. BMI was most strongly associated with admissions with diabetes, knee-replacement, gallbladder disease and venous thromboembolism, but marked associations were found with many other common categories of admission including cataracts, carpal tunnel syndrome and diverticulitis.

CONCLUSIONS

Among women 50- to 84-years old in England, around one in eight hospital admissions are likely to be attributable to overweight or obesity, translating to around 420,000 extra hospital admissions and two million extra days spent in hospital, annually.

The impact of asbestos exposure in Swedish construction workers

OBJECTIVE

To study the occurrence of pleural mesothelioma as a measure of the impact on health from asbestos exposure in the construction industry.

METHODS

The occurrence of pleural mesothelioma in different occupations, time periods and birth cohorts was studied in a cohort of construction workers. They were prospectively followed after they had participated in health examinations between 1971 and 1993. The analysis was restricted to men and in total 367,568 men was included in the analysis.

RESULTS

In total there were 419 cases of pleural mesotheliomas between 1972 and 2009. As expected the age adjusted incidence was high in insulation workers and plumbers (39 and 16 cases per 100,000 person-years, respectively). However, only 21% of the pleural mesotheliomas occurred in those occupational groups. Occupational groups with many cases of pleural mesothelioma were concrete workers (N = 56), wood workers (N = 55), painters (N = 32), electricians (N = 48), and foremen (N = 37). The highest risk was in birth cohorts born between 1935 and 1945. Between 1995 and 2009 around one-third of all male cases in the country occurred in this birth cohort. The risk seemed to decrease considerably in men born after 1955.

CONCLUSION

In Sweden a considerable proportion of pleural mesotheliomas occur among construction workers; and not only in jobs traditionally associated with asbestos exposure such as insulators and plumbers but also among electricians, for example. The results shows that asbestos exposure occurs in many occupational groups, indicating that safe handling of asbestos is a very difficult or even impossible task in the construction industry.

Longitudinal assessment of liver stiffness in patients undergoing antiviral treatment for hepatitis C

BACKGROUND

Liver stiffness has been suggested as a parameter of fibrosis progression/regression in hepatitis C virus (HCV) patients.

AIM

To evaluate stiffness before and after peginterferon-ribavirin treatment.

METHODS

Stiffness was prospectively measured in 74 HCV patients, 32 genotypes 1/4 (43.25%) and 42 genotypes 2/3 (56.75%), before, at end of treatment, and after 3 years of follow-up (49 patients). On the same study day, 21 patients underwent liver biopsy.

RESULTS

In 55 patients with sustained virological response (74.32%), liver stiffness decreased significantly at end of therapy (6.8±4.9kPa) vs. baseline (9.5±6.9kPa, p=0.04). The decrease vs. baseline was maintained in 30 sustained virological response patients after 3 years follow-up (6.8±4.6kPa vs. 10.8±8.5kPa, p=0.0141). No difference was found at end of treatment vs. baseline (10.1±4.7kPa vs. 9.7±4.2kPa, p=0.825) and after 3 years of follow-up vs. baseline (10.2±3.4kPa vs. 9.7±4.2kPa, p=0.765) in null responders. Similar results were found in relapsers at end of treatment vs. baseline (13.7±7.7kPa vs. 15.2±8.2kPa, p=0.74), and after 3 years of follow-up vs. baseline (16.9±10.0kPa vs. 15.2±8.2kPa, p=0.734). Pre-treatment stiffness >12kPa was significantly associated with no SVR (p<0.025), RR=2.44 (95%C.I. 1.17-5.07).

CONCLUSION

Liver stiffness may be useful to assess long-term antiviral treatment response.

Population attributable risk fraction for selected chronic diseases in India

BACKGROUND

India's current health transition stage poses a critical challenge of dealing with the unfinished agenda of communicable diseases and the steadily rising burden of noncommunicable diseases. A significant burden of chronic diseases in India is attributable to household and individual level health risk factors coupled with socioeconomic conditions. From this perspective, this article made a first time effort to assess disease burden attributable to health risk factors using cross-sectional population health survey data.

METHODS

Population attributable fractions (PAF) were estimated for a cluster of health risk factors that include unsafe water, lack of sanitation, exposure to cooking smoke, tobacco and alcohol use, physical inactivity, and socioeconomic conditions on a set of widely prevalent chronic diseases such as tuberculosis, malaria, diarrhea, diabetes, angina, and asthma. Data from the 2003 World Health Survey was used.

RESULTS

The analysis revealed evidence of a significant contribution of health risk factors to India's escalating chronic disease burden. The contribution of health risk factors toward chronic disease burden varied by residence.

CONCLUSION

Results suggest that promotional health care based policies to deal with health risks should be a major priority in policy agenda to combat with the challenge of emerging noncommunicable disease coupled with the persistent burden of communicable diseases. Disease burden in India could be halved by effectively modifying exposure to the risk factors through promotional health care.

Mortality due to cancer among people with AIDS: a novel approach using registry-linkage data and population attributable risk methods

OBJECTIVE

Deaths related to HIV/AIDS have declined due to improved HIV therapies. However, people with AIDS remain at elevated risk for cancer and cancer deaths. Prior studies evaluated cancer deaths using death certificates, which may be inaccurate. We utilized population attributable risk methods (which do not rely on death certificates) to assess cancer mortality.

DESIGN

Data from a US population-based record linkage study were used to identify incident cancers and deaths in 372 364 people with AIDS (1980-2006) followed for up to 5 years after AIDS onset. We utilized Cox regression to compare mortality in individuals with and without cancer and to calculate cancer-attributable mortality across calendar periods (AIDS onset in 1980-1989, 1990-1995, and 1996-2006).

RESULTS

Mortality declined across calendar periods for all people with AIDS but remained higher among those with cancer relative to those without. During 1996-2006, among individuals with an AIDS-defining cancer (ADC) who died, 88.3% of deaths were attributable to their ADC; likewise, among individuals with a non-AIDS-defining cancer (NADC), 87.1% of deaths were attributable to their NADC. The fraction of all deaths in people with AIDS attributable to ADC (i.e. population-attributable risk) decreased significantly from 6.3% (1980-1990) to 3.9% (1996-2006), but NADC population attributable mortality increased significantly over time from 0.5% (1980-1989) to 2.3% (1996-2006).

CONCLUSION

Among individuals with AIDS and cancer who subsequently die, most deaths are attributable to cancer. With a decline in overall mortality, the proportion of all deaths attributable to NADCs has increased. These results highlight the need for improved cancer prevention and treatment.

Injuries associated with housing conditions in Europe: a burden of disease study based on 2004 injury data

BACKGROUND

The authors recently undertook a study for the World Health Organization estimating the European burden of injuries that can be attributed to remediable structural hazards in the home. Such estimates are essential for motivating injury prevention efforts as they quantify potential health gains, in terms of injuries prevented, via specific environmental interventions.

METHODS

We combined exposure estimates from existing surveys and scenarios with estimates of the exposure-risk relationship obtained from a structured review of the literature on injury in the home and housing conditions. The resulting attributable fractions were applied to burden of injury data for the WHO European Region.

RESULTS

This analysis estimated that two specific hazards, lack of window guards at second level and higher, and lack of domestic smoke detectors resulted in an estimated 7,500 deaths and 200,000 disability adjusted life years (DALYs) per year. In estimating the environmental burden of injury associated with housing, important deficiencies in injury surveillance data and related limitations in studies of injury risk attributable to the home environment were apparent. The ability to attribute proportions of the home injury burden to features of the home were correspondingly limited, leading to probable severe underestimates of the burden.

CONCLUSIONS

The burden of injury from modifiable home injury exposures is substantial. Estimating this burden in a comprehensive and accurate manner requires improvements to the scope of injury surveillance data and the evidence base regarding the effectiveness of interventions.

Defining risk drinking

Many efforts to prevent alcohol-related harm are aimed at reducing risk drinking. This article outlines the many conceptual and methodological challenges to defining risk drinking. It summarizes recent evidence regarding associations of various aspects of alcohol consumption with chronic and acute alcohol-related harms, including mortality, morbidity, injury, and alcohol use disorders, and summarizes the study designs most appropriate to defining risk thresholds for these types of harm. In addition, it presents an international overview of low-risk drinking guidelines from more than 20 countries, illustrating the wide range of interpretations of the scientific evidence related to risk drinking. This article also explores the impact of drink size on defining risk drinking and describes variation in what is considered to be a standard drink across populations. Actual and standard drink sizes differ in the United States, and this discrepancy affects definitions of risk drinking and prevention efforts.

Independent and dependent contributions of advanced maternal and paternal ages to autism risk

Reports on autism and parental age have yielded conflicting results on whether mothers, fathers, or both, contribute to increased risk. We analyzed restricted strata of parental age in a 10-year California birth cohort to determine the independent or dependent effect from each parent. Autism cases from California Department of Developmental Services records were linked to State birth files (1990-1999). Only singleton births with complete data on parental age and education were included (n=4,947,935, cases=12,159). In multivariate logistic regression models, advancing maternal age increased risk for autism monotonically regardless of the paternal age. Compared with mothers 25-29 years of age, the adjusted odds ratio (aOR) for mothers 40+ years was 1.51 (95% CI: 1.35-1.70), or compared with mothers <25 years of age, aOR=1.77 (95% CI, 1.56-2.00). In contrast, autism risk was associated with advancing paternal age primarily among mothers <30: aOR=1.59 (95% CI, 1.37-1.85) comparing fathers 40+ vs. 25-29 years of age. However, among mothers >30, the aOR was 1.13 (95% CI, 1.01-1.27) for fathers 40+ vs. 25-29 years of age, almost identical to the aOR for fathers <25 years. Based on the first examination of heterogeneity in parental age effects, it appears that women's risk for delivering a child who develops autism increases throughout their reproductive years whereas father's age confers increased risk for autism when mothers are <30, but has little effect when mothers are past age 30. We also calculated that the recent trend towards delayed childbearing contributed approximately a 4.6% increase in autism diagnoses in California over the decade.

The disease burden attributable to smoking in the state of Rio de Janeiro, Brazil in 2000

INTRODUCTION

Smoking is one of the main risk factors for morbidity and mortality. An estimated 59 million (4.4%) disability-adjusted life years were lost due to smoking throughout the world in 2000.

OBJECTIVE

To estimate the disease burden attributable to smoking in the State of Rio de Janeiro, Brazil, for the year 2000.

METHODS

Based on estimates of smoking prevalence and relative death risks, the smoking-attributable fraction was calculated for each selected cause, by age and gender. The disease burden attributable to smoking was estimated by multiplying the fractions by the corresponding disability-adjusted life years.

RESULTS

In the State of Rio de Janeiro, 7% of all disability-adjusted life years were due to smoking. For individuals 30 or more years old, the fraction increased to 10.6% (13.6% in males and 7.5% in females). Chronic obstructive pulmonary disease, ischemic heart disease, cerebrovascular disease, and tracheal, bronchial, and lung cancer accounted for 32.2%, 15.7%, 13.2%, and 11.1% of the estimated total DALYs, respectively, amounting to 72.2% of the smoking-attributable disease burden.

DISCUSSION

Limitations related to parameter estimates were not unique to this study, and therefore should not compromise the comparability of our results. Outcomes were similar to those obtained in other countries, despite methodological differences.

CONCLUSION

Smoking is an important risk factor and places a significant disease burden on Rio de Janeiro, Brazil, showing a pattern similar to that observed in high income countries.

Excess mortality following hip fracture: the role of underlying health status

We evaluated the long-term excess mortality associated with hip fracture, using prospectively collected data on pre-fracture health and function from a nationally representative sample of U.S. elders. Although mortality was elevated for the first six months following hip fracture, we found no evidence of long-term excess mortality.

INTRODUCTION

The long-term excess mortality associated with hip fracture remains controversial.

METHODS

To assess the association between hip fracture and mortality, we used prospectively collected data on pre-fracture health and function from a representative sample of U.S. elders in the Medicare Current Beneficiary Survey (MCBS) to perform survival analyses with time-varying covariates.

RESULTS

Among 25,178 MCBS participants followed for a median duration of 3.8 years, 730 sustained a hip fracture during follow-up. Both early (within 6 months) and subsequent mortality showed significant elevations in models adjusted only for age, sex and race. With additional adjustment for pre-fracture health status, functional impairments, comorbid conditions and socioeconomic status, however, increased mortality was limited to the first six months after fracture (hazard ratio [HR]: 6.28, 95% CI: 4.82, 8.19). No increased mortality was evident during subsequent follow-up (HR: 1.04, 95% CI: 0.88, 1.23). Hip-fracture-attributable population mortality ranged from 0.5% at age 65 among men to 6% at age 85 among women.

CONCLUSIONS

Hip fracture was associated with substantially increased mortality, but much of the short-term risk and all of the long-term risk was explained by the greater frailty of those experiencing hip fracture.