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American Journal of Public Health

Journal of Epidemiology & Community Health current issue
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Journal of Epidemiology & Community Health

The primary determinants of disease are mainly economic and social, and therefore its remedies must also be economic and social. Medicine and politics cannot and should not be kept apart. Rose1

To achieve [a reduction in overweight and obesity] is perhaps the major public health and societal challenge of the century. Potential strategies include [....] redesign of built environments to promote physical activity, changes in food systems, restrictions on aggressive promotion of unhealthy drinks and foods to children and economic strategies such as taxation. Willet2

Non-communicable diseases (NCDs)—mainly cancers, cardiovascular diseases (CVDs), diabetes and chronic respiratory diseases—are the main causes of death and morbidity worldwide.3 NCDs are now annually responsible for more than 35 million deaths in the world with more than 80% of this disease burden occurring in low-income and middle-income countries.4 At the same time, NCDs are...


Obesity is a major public health problem because it is a risk factor for metabolic disorders including type 2 diabetes and cardiovascular disorders. Its evolution is pandemic with more than 1.4 billion adults overweight in 2008, and the WHO predicts that by 2015 about 700 million people will be obese. Nowadays, an estimate of 347 million people worldwide has diabetes, and diabetes is projected to be the seventh leading cause of death in 2030.1 In addition, diabetes has a heavy cost on the economy and quality of life. For example, the total estimated cost of diagnosed diabetes in 2012 in the USA was $245 billion.2 Type 2 diabetes results from the body's ineffective use of insulin, a hypoglycaemic hormone secreted by the pancreas that plays a major metabolic role in maintaining blood glucose levels in the normal range. The first step leading to diabetes is...


Background

In New Zealand, the burden of childhood obesity is greatest in Māori and Pacific children.

Methods

In 687 infants from an internet-based birth cohort in New Zealand, we investigated ethnic differences in early life risk factors for later obesity, the degree to which these were explained by sociodemographic factors, and the extent to which ethnic differences in weight at age 3 months were explained by measured risk factors.

Results

The risk of having an obese mother was double in Māori and Pacific infants compared with NZ European infants (prevalence 24% and 14%, respectively; OR 2.23, 95% CI 1.23 to 4.04). Māori and Pacific infants had higher weights in the first week of life and at 3 months (mean difference 0.19 kg, 95% CI 0.01 to 0.38), and their mothers had higher scores on a ‘snacks’ dietary pattern and lower scores on ‘healthy’ and ‘sweet’ dietary patterns. These inequalities were not explained by maternal education, maternal age or area-based deprivation. No ethnic differences were observed for maternal pre-pregnancy physical activity, hypertension or diabetes in pregnancy, exclusive breastfeeding or early introduction of solid foods. Ethnic inequalities in infant weight at 3 months were not explained by sociodemographic variables, maternal pre-pregnancy body mass index or dietary pattern scores or by other measured risk factors.

Conclusions

This study shows excess prevalence of early life risk factors for obesity in Māori and Pacific infants in New Zealand and suggests an urgent need for early interventions for these groups.


Background

Increasing global urbanisation has resulted in a greater proportion of the world's population becoming exposed to risk factors unique to urban areas, and understanding these effects on public health is essential. The aim of this study was to examine the association between access to green space and mental health among adult twin pairs.

Methods

We used a multilevel random intercept model of same-sex twin pairs (4338 individuals) from the community-based University of Washington Twin Registry to analyse the association between access to green space, as measured by the Normalised Difference Vegetation Index and self-reported depression, stress, and anxiety. The main parameter of interest was the within-pair effect for identical (monozygotic, MZ) twins because it was not subject to confounding by genetic or shared childhood environment factors. Models were adjusted for income, physical activity, neighbourhood deprivation and population density.

Results

When treating twins as individuals and not as members of a twin pair, green space was significantly inversely associated with each mental health outcome. The association with depression remained significant in the within-pair MZ univariate and adjusted models; however, there was no within-pair MZ effect for stress or anxiety among the models adjusted for income and physical activity.

Conclusions

These results suggest that greater access to green space is associated with less depression, but provide less evidence for effects on stress or anxiety. Understanding the mechanisms linking neighbourhood characteristics to mental health has important public health implications. Future studies should combine twin designs and longitudinal data to strengthen causal inference.


Background

The English NHS Bowel Cancer Screening Programme has offered biennial faecal occult blood testing to people aged 60–69 years since 2006, and to those aged 60–74 years since 2010. Analysis of the first 2.6 million screening invitations found that 54% of eligible people took up the invitation. The reasons for this low uptake are unclear. We investigated whether participation in screening varies according to cognitive ability and personality.

Methods

Participants were members of The English Longitudinal Study of Ageing. In 2010–2011, respondents were asked about participation in bowel cancer screening, and cognitive ability and the ‘Big Five’ personality traits were assessed. Logistic regression was used to examine the cross-sectional relationships between cognitive ability and personality and screening participation in 2681 people aged 60–75 years who were eligible to have been invited to take part in the UK national screening programme for bowel cancer.

Results

In age-adjusted and sex-adjusted analyses, better cognition and higher conscientiousness were associated with increased participation in cancer screening. ORs (95% CIs) per SD increase were 1.10 (1.03 to 1.18) for cognitive ability and 1.10 (1.01 to 1.19) for conscientiousness. After further adjustment for household wealth and health literacy—shown previously to be associated with participation—these associations were attenuated (ORs were 1.07 (1.00 to 1.15) and 1.07 (0.97 to 1.18), respectively).

Conclusions

We found some indication that better cognitive function and greater conscientiousness may be linked with a slightly increased likelihood of participation in bowel cancer screening. These relationships need investigation in other cohorts of older people.


Background

Since 2002, Dutch mortality rates decreased rapidly after decades of stagnation. On the basis of indirect evidence, previous research has suggested that this decline was due to a sudden expansion of healthcare. We tested two corollaries of this hypothesis—first, that the decline was concentrated among those with ill-health and second, that the decline can be statistically accounted for by increases in healthcare utilisation.

Methods

We linked the Dutch health interview survey to the mortality register and constructed two cohorts, consisting of 7691 persons interviewed in 2001/2002 and 8362 persons interviewed in 2007/2008, each with a 5-year mortality follow-up (659 deaths in total). The change in mortality between both cohorts was computed using Cox proportional hazard models. We estimated the change in mortality by severity of chronic conditions and with respect to the inclusion of indicators of healthcare utilisation.

Results

Between the two study cohorts, mortality declined by 15% (95% CI 2% to 29%), and mortality reduction was greatest for those suffering from fatal and non-fatal conditions with a decline of 58% (95% CI 35% to 78%). Even after adjustment for health status and risk factors, most indicators of healthcare utilisation were associated with higher instead of lower mortality and changes in healthcare utilisation did not explain the decline in mortality.

Conclusions

Our results only partly confirm the hypothesis that an expansion of healthcare explains the recent mortality decline in the Netherlands. Owing to confounding by health status, it is difficult to reproduce the mortality-lowering effects of healthcare utilisation of individual level studies in the open population.


Background

We examined whether higher effort–reward imbalance (ERI) and lower job control are associated with exit from the labour market.

Methods

There were 1263 participants aged 50–74 years from the English Longitudinal Study on Ageing with data on working status and work-related psychosocial factors at baseline (wave 2; 2004–2005), and working status at follow-up (wave 5; 2010–2011). Psychosocial factors at work were assessed using a short validated version of ERI and job control. An allostatic load index was formed using 13 biological parameters. Depressive symptoms were measured using the Center for Epidemiologic Studies Depression Scale. Exit from the labour market was defined as not working in the labour market when 61 years old or younger in 2010–2011.

Results

Higher ERI OR=1.62 (95% CI 1.01 to 2.61, p=0.048) predicted exit from the labour market independent of age, sex, education, occupational class, allostatic load and depression. Job control OR=0.60 (95% CI 0.42 to 0.85, p=0.004) was associated with exit from the labour market independent of age, sex, education, occupation and depression. The association of higher effort OR=1.32 (95% CI 1.01 to 1.73, p=0.045) with exit from the labour market was independent of age, sex and depression but attenuated to non-significance when additionally controlling for socioeconomic measures. Reward was not related to exit from the labour market.

Conclusions

Stressful work conditions can be a risk for exiting the labour market before the age of 61 years. Neither socioeconomic position nor allostatic load and depressive symptoms seem to explain this association.


Background

In addition to being associated with all-cause mortality and cardiovascular disease mortality, lung function has been linked with dementia. However, existing studies typically provide imprecise estimates due to small numbers of outcome events and are based on unrepresentative samples of the general population.

Methods

Individual participant meta-analysis of six cohort studies from the Health Survey for England and the Scottish Health Survey (total N=54 671). Dementia-related mortality was identified by mention of dementia on any part of the death certificate (mean follow-up 11.7 years). Study-specific Cox proportional hazard models of the association between lung function and dementia-related death were pooled using random effect meta-analysis to produce overall results.

Results

There was a dose–response association between poorer lung function and a higher risk of dementia-related death (age- and sex-adjusted HR compared to highest quartile of forced expiratory volume in 1 s (FEV1), 95% CI: second quartile 1.32, 0.99 to 1.76; third quartile 1.78, 1.30 to 2.43; fourth (lowest) quartile 2.74, 1.73 to 4.32). There was no significant heterogeneity in study-specific estimates (I2=0%). Controlling for height, socioeconomic status, smoking and general health attenuated but did not remove the association (second quartile 1.15, 0.82 to 1.62; third quartile 1.37, 0.96 to 1.94; fourth quartile 2.09, 1.17 to 3.71). Results for forced vital capacity and peak flow were similar.

Conclusions

In these general population samples, the relation between three measures of lung function and dementia death followed a dose–response gradient. Being in the bottom quartile of lung function was associated with a doubling of the risk.


Background

Few studies have investigated the relationship between carbon monoxide (CO) poisoning and risk of deep vein thrombosis (DVT) and pulmonary embolism (PE). Therefore, we conducted a nationwide longitudinal cohort study in Taiwan to determine whether patients with CO poisoning are associated with increased risk of developing DVT and PE.

Methods

This study investigated the incidence and risk factors for DVT and PE in 8316 patients newly diagnosed with CO poisoning from the Taiwan National Health Insurance Research Database between 2000 and 2011. The comparison cohort contained 33 264 controls without CO poisoning from the general population. Follow-up was initiated on the date of initial diagnosis of CO poisoning and continued until the date of a DVT or PE event, censoring or December 31, 2011. Cox proportional hazard regression models were used to analyse the risk of DVT and PE according to sex, age and comorbidities.

Results

The incidences of DVT and PE were higher in the patients with CO poisoning than in the controls (5.67 vs 1.47/10 000 person-years and 1.97 vs 1.02/10 000 person-years, respectively). After adjusting for age, sex and comorbidities, the patients with CO poisoning were associated with a 3.85-fold higher risk of DVT compared with the comparison cohort, and non-significantly associated with risk of PE. CO poisoning patients with a coexisting comorbidity or acute respiratory failure were associated with significantly and substantially increased risk of DVT.

Conclusion

Risk of DVT is significantly higher in patients with CO poisoning than in the general population.


Background

Low IQ has been shown to be an important risk factor for disability pension (DP) but whether the importance has changed over time remains unclear. It can be hypothesised that IQ has become more important for DP over time in parallel with a more demanding working life. The aim of this study was to investigate the relative risk of low IQ on the risk of DP before age 30 between 1971 and 2006.

Methods

This study covered the entire Swedish male population born between 1951 and 1976, eligible for military conscription. Information about the study subjects was obtained by linkage of national registers. Associations between IQ and DP over time were analysed by descriptive measures (mean values, proportions, etc) and by Cox proportional hazards regressions. Analyses were adjusted for educational level.

Results

The cohort consisted of 1 229 346 men. The proportion that received DP before the age of 30 increased over time, from 0.68% in the cohort born between 1951 and 1955 to 0.95% in the cohort born between 1971 and 1976. The relative risk of low IQ (adjusted for education) in relation to high IQ decreased from 5.68 (95% CI 4.71 to 6.85) in the cohort born between 1951 and 1955 to 2.62 (95% CI 2.25 to 3.05) in the cohort born between 1971 and 1976.

Conclusions

Our results gave no support to the idea that the importance of low IQ for the risk of DP has increased in parallel with increasing demands in working life. In fact, low IQ has become less important as a risk factor for DP compared with high IQ between the early 1970s and 1990s. An increased educational level over the same time period is likely to be part of the explanation.


Background

A positive association between smoking and increased risk of tuberculosis disease is well documented for populations outside the USA. However, it is unclear whether smoking increases risk of tuberculosis in the USA, where both smoking prevalence and disease rates are much lower than in the countries where previous studies have been conducted.

Methods

To explore the tuberculosis–smoking association in a more generalisable US population-based sample, we conducted a nested case–control study among members of Kaiser Permanente Northern California (KPNC). We identified all newly diagnosed cases of active pulmonary tuberculosis (PTB) disease between 1996 and 2010. Each of the 2380 cases were individually matched to two controls by age, gender and race/ethnicity. ORs and 95% CIs for the association between smoking status and PTB were calculated using conditional logistic regression adjusted for all matching factors.

Results

Increased PTB risk was observed among ever-smokers (OR=1.35; 95% CI 1.19 to 1.53), as well as current (OR=1.26; 95% CI 1.08 to 1.48) and past (OR=1.43; 95% CI 1.23 to 1.67) smokers, compared with never-smokers. Increased intensity and duration of smoking were also positively associated with PTB risk.

Conclusions

Our findings among a more generalisable US population support the hypothesis that smoking increases risk of PTB, underscoring the importance of tobacco cessation and prevention programmes in eliminating tuberculosis.


Background

Attempts at predicting individual risk of disease based on common germline genetic variation have largely been disappointing. The present paper formalises why genetic prediction at the individual level is and will continue to have limited utility given the aetiological architecture of most common complex diseases.

Methods

Data were simulated on one million populations with 10 000 individuals in each populations with varying prevalences of a genetic risk factor, an interacting environmental factor and the background rate of disease. The determinant risk ratio and risk difference magnitude for the association between a gene variant and disease is a function of the prevalence of the interacting factors that activate the gene, and the background rate of disease.

Results

The risk ratio and total excess cases due to the genetic factor increase as the prevalence of interacting factors increase, and decrease as the background rate of disease increases. Germline genetic variations have high predictive capacity for individual disease only under conditions of high heritability of particular genetic sequences, plausible only under rare variant hypotheses.

Conclusions

Under a model of common germline genetic variants that interact with other genes and/or environmental factors in order to cause disease, the predictive capacity of common genetic variants is determined by the prevalence of the factors that interact with the variant and the background rate. A focus on estimating genetic associations for the purpose of prediction without explicitly grounding such work in an understanding of modifiable (including environmentally influenced) factors will be limited in its ability to yield important insights about the risk of disease.


Background

Low socioeconomic status (SES) has been associated with higher risk of cardiometabolic diseases in developed societies, but investigation of SES and cardiometabolic risk in children in less economically developed populations is sparse. We aimed to examine associations among SES and cardiometabolic risk factors in Colombian children.

Methods

We used data from a population-based study of 1282 children aged 6–10 years from Bucaramanga, Colombia. SES was classified according to household wealth, living conditions and access to public utilities. Anthropometric and biochemical parameters were measured at a clinic visit. Cardiometabolic risk factors were analysed continuously using linear regression and as binary outcomes—according to established paediatric cut points—using logistic regression to calculate OR and 95% CIs.

Results

Mean age of the children was 8.4 (SD 1.4) and 51.1% of the sample were boys. Odds of overweight/obesity, abdominal obesity and insulin resistance were greater among higher SES. Compared with the lowest SES stratum, children in the highest SES had higher odds of overweight/obesity (OR=3.25, 95% CI 1.89 to 5.57), abdominal obesity (OR=2.74, 95% CI 1.41 to 5.31) and insulin resistance (OR=2.60, 95% CI 1.81 to 3.71). In contrast, children in the highest SES had lower odds of hypertriglyceridaemia (triglycerides ≥90th centile; OR=0.28, 95% CI 0.14 to 0.54) and low (≤10th centile) high-density lipoprotein (HDL) cholesterol (OR=0.35, 95% CI 0.15 to 0.78).

Conclusions

In Colombian children, SES is directly associated with obesity and insulin resistance, but inversely associated with dyslipidaemia (hypertriglyceridaemia and low HDL cholesterol). Our findings highlight the need to analyse cardiometabolic risk factors separately in children and to carefully consider a population's level of economic development when studying their social determinants of cardiometabolic disease.


Background

Young adults at work without basic educational level (BEL), and young adults in Neither Employment, Education nor Training (NEET) are at high risk of adverse employment outcomes. Evidence lacks on the impact of mental health problems during childhood, adolescence and young adulthood on employment outcomes of young adults. Therefore, the aims of this study were to (1) identify trajectories of mental health problems from childhood to young adulthood and (2) investigate the relation between these trajectories and the educational or employment status of young adults.

Methods

Data were used from the Tracking Adolescents’ Individual Lives Survey (TRAILS), a Dutch prospective cohort study with 9-year follow-up. Trajectories of mental health problems measured at ages 11, 13.5, 16 and 19 years were identified in 1711 young adults with latent class growth models.

Results

Young adults with high-stable trajectories of total problems, from childhood to young adulthood, were more likely to work without BEL or be in NEET at age 19, than to be at school or to work with BEL (28.0% vs 16.0%, p=0.01). The same was found for externalising problems (35.3% vs 23.2%, p=0.02). For internalising and attention problems, no statistically significant differences were found.

Conclusions

Young adults with high-stable trajectories of mental health problems from age 11 to 19, were at risk of adverse employment outcomes. Interventions reducing mental health problems in childhood may improve the educational or employment status of young adults and their chances for successfully entering the labour market.


Objective

The global prevalence of metabolic syndrome (MetS) appears to be increasing and the impact of this condition on potential comorbidities such as cardiovascular disease is high. Chronic kidney disease (CKD) is also a potential comorbidity of MetS but the method of screening for this is somewhat controversial. Thus, predictive markers that can predict the risk of developing CKD are warranted for identification of patients with MetS at an increased risk.

Research methods/patients

We investigated the occurrence of CKD in 6492 individuals, either with or without MetS.

Results

Our results showed that the prevalence of CKD was markedly higher in those individuals with MetS, and increased progressively with the number of MetS components and age. Waist circumference, triglycerides and high-density lipoprotein cholesterol were significantly (p<0.05) associated with altered levels of urea nitrogen, glomerular filtration rate and creatinine, and were related to the increased risk of CKD (eg, OR 1.293 (95% CI 1.10 to 1.52; p=0.002)). The relative risk of CKD remained statistically significant for uric acid following multivariate analyses and adjusting for MetS-associated factors.

Conclusions

Our data demonstrated the association of MetS components with CKD in our population and revealed that susceptibility to CKD was increased with the number of defining features of MetS. These findings prompt prospective studies to determine the impact of preventing and detecting MetS on the risk of developing CKD.


Background

Cohort studies on hepatitis C virus (HCV) among drug injectors are scarcer than studies on HIV. Combined harm reduction interventions (HRIs) can prevent HCV infection. Spain has a medium–high coverage of HRIs.

Methods

513 young heroin users who injected drugs in the past 12 months (recent injectors) were street-recruited in 2001–2003 and followed until 2006 in three Spanish cities; 137 were anti-HCV seronegative, 77 of whom had ≥1 follow-up visit. Dried blood spots were tested for anti-HCV. HCV incidence and predictors of infection were estimated using Poisson models.

Results

At baseline, 73% were anti-HCV positive. Overall incidence (n=77) of HCV seroconversion was 39.8/100 person-years (py) (95% CI 28.7 to 53.8). Excluding non-injectors during follow-up from the analysis (n=57), HCV incidence was 52.9/100 py (95% CI 37.4 to 72.5). Injecting at least weekly (incidence rate ratio (IRR)=5.2 (95% CI 2.5 to 11.1)) and having ≥2 sexual partners (IRR=2.2 (95% CI 1.1 to 4.7)) were independent predictors of HCV seroconversion; drug-injection history <2 years was marginally associated (IRR=2.4 (95% CI 0.9 to 4.7)). HCV incidence may have been underestimated due to differential attrition.

Conclusions

Despite fairly high HRI coverage among Spanish drug injectors, a distressingly high incidence of HCV in a context of high HCV prevalence was found among young heroin injectors.


Background

The developing world accounts for 99% of global maternal deaths. Men in developing countries are the chief decision-makers, determining women's access to maternal health services and influencing their health outcomes. At present, it is unclear whether involving men in maternal health can improve maternal outcomes. This systematic review and meta-analysis aimed to investigate the impact of male involvement on maternal health outcomes of women in developing countries.

Methods

Four electronic databases and grey literature sources were searched (up to May 2013), together with reference lists of included studies. Two reviewers independently screened and assessed the quality of studies based on prespecified criteria. Measures of effects were pooled and random effect meta-analysis was conducted, where possible.

Results

Fourteen studies met the inclusion criteria. Male involvement was significantly associated with reduced odds of postpartum depression (OR=0.36, 95% CI 0.19 to 0.68 for male involvement during pregnancy; OR=0.34, 95% CI 0.19 to 0.62 for male involvement post partum), and also with improved utilisation of maternal health services (skilled birth attendance and postnatal care). Male involvement during pregnancy and at post partum appeared to have greater benefits than male involvement during delivery.

Conclusions

Male involvement is associated with improved maternal health outcomes in developing countries. Contrary to reports from developed countries, there was little evidence of positive impacts of husbands’ presence in delivery rooms. However, more rigorous studies are needed to improve this area's evidence base.