Genetically predicted higher educational attainment decreases the risk of stroke: a multivariable Mendelian randomization study

Background

The causal association between educational attainment (EA) and stroke remains unclear. Hence, a novel multivariable Mendelian randomization (MVMR) approach was applied to solve this issue.

Methods

The single nucleotide polymorphisms (SNPs) from a recent genome-wide association study (GWAS) on years of schooling served as instruments. Univariable mendelian randomization (MR) and MVMR analyses were performed to detect the relationship between genetically predicted EA and the stroke risk. In the MVMR, cigarette consumption, alcohol consumption, body mass index (BMI), intelligence, and hypertension were adjusted. The summary statistics for stroke from the MEGASTROKE consortium included 446,696 participants (40,585 cases of stroke and 34,217 cases of ischemic stroke), most of whom were of European descent.

Results

In the univariable MR, genetically predicated EA could decrease the risks of total stroke (OR = 0.66, 95% CI 0.61–0.72, P = 2.70 × 10^–23), ischemic stroke (OR = 0.67, 95% CI 0.61–0.73, P = 2.58 × 10^–18), large artery atherosclerosis (OR = 0.51, 95% CI 0.40–0.64, P = 1.80 × 10^–8), small vessel stroke (OR = 0.60, 95% CI 0.49–0.73, P = 5.59 × 10^–7), and cardioembolic stroke (OR = 0.81, 95% CI 0.68–0.96, P = 1.46 × 10^–2) using the inverse-variance weighted (IVW) estimator. Higher EA might be negatively correlated with the odds of total stroke (OR = 0.62, 95% CI 0.50–0.77, P = 1.44 × 10^–5), ischemic stroke (OR = 0.63, 95% CI 0.50–0.80, P = 1.41 × 10^–4), and cardioembolic stroke (OR = 0.59, 95% CI 0.39–0.90, P = 0.01), but was not significant in large artery atherosclerosis (OR = 0.65, 95% CI 0.37–1.15, P = 0.14) and small vessel stroke (OR = 0.68, 95% CI 0.41–1.13, P = 0.14) after controlling other exposures.

Conclusions

We found that genetically predicated higher EA decreased the risks of total stroke, ischemic stroke, and cardioembolic stroke, independent of smoking, alcohol consumption, BMI, intelligence, and hypertension.

Multiple Socioeconomic Circumstances and Initiation of Cardiovascular Medication among Ageing Employees

There are persisting socioeconomic differences in cardiovascular diseases, but studies on socioeconomic differences in the initiation of cardiovascular medication are scarce. This study examined the associations between multiple socioeconomic circumstances and cardiovascular medication. The Helsinki Health Study baseline survey (2000-2002) of 40-60-year-old employees was linked with cardiovascular medication data from national registers. The analyses included 5805 employees concerning lipid medication and 4872 employees concerning hypertension medication. Medication purchases were followed for 10 years. The analyses were made using logistic regression, and the odds ratios (ORs) and their 95% confidence intervals (CIs) were calculated for childhood, conventional and material socioeconomic circumstances. Low parental education showed an association with lipid medication among women only (OR 1.34, 95% CI 1.11-1.61), whereas childhood economic difficulties showed more widespread associations. Low education and occupational class were associated with an increased risk of both hypertension (education: OR 1.58, 1.32-1.89; occupational class: 1.31, 1.08-1.59) and lipid medication (education: 1.34, 1.12-1.61; occupational class: 1.38, 1.13-1.67). Rented housing (1.35, 1.18-1.54 for hypertension medication; 1.21, 1.05-1.38 for lipid medication) and current economic difficulties (1.59, 1.28-1.98 for hypertension medication; 1.35, 1.07-1.71 for lipid medication) increased the risk. Several measures of socioeconomic circumstances acting at different stages of the life course were associated with cardiovascular medication, with individuals in disadvantageous socioeconomic circumstances having elevated risks.

A cohort study on the relationship between education level and high-risk population of stroke

Objective

To explore the relationship between education level and high-risk population among stroke screening populations in Zunyi City, China.

Methods

The cluster sampling method was adopted to collect the medical history, laboratory examinations and physical examinations for the permanent residents of Zunyi City, Guizhou Province. Taking education level as a key socioeconomic status (SES) indicator, multivariate logistic regression analysis was used to evaluate the risk factors of high-risk groups with different education levels.

Results

Among the included 4149 subjects, 494 were in the high-risk group and 3655 were in the non-high-risk group. The proportion of the high-risk population with education level ≥ high secondary school (8.7%) was significantly higher than that of the low-risk population. After adjusting for age, gender, and BMI, the OR of those with education leve l ≥ high secondary school was 2.8 (95% CI 1.9-4.2), which was significantly higher than those with education level of illiterate/primary school. In the model adjusted for all confounding factors, compared with illiterate/primary school, people with education level ≥ high secondary school were more likely to be at high risk of stroke (OR 3.0, 95% CI 1.9-4.6).

Conclusion

Education level ≥ high secondary school is an independent influencing factor for the high-risk population of stroke in Zunyi, which may be related to smoking and lipid metabolism abnormalities of people with high education level. Key interventions for high-risk populations with high education levels may have positive significance in reducing the incidence of stroke.

Housing and Cardiometabolic Risk Among Older Renters and Homeowners

Scholars consistently find that renters have poorer health outcomes when compared with homeowners. Health disparities between renters and homeowners likely widen over the life course, yet few studies have examined this link among older adults, and the connection is not fully understood. Homeowners' relative socioeconomic advantage may explain their better health; renters also more commonly experience adverse housing conditions and financial challenges, both of which can harm health. In this paper, we analyze the extent to which socioeconomic advantage, housing conditions, and financial strain explain the relationship between homeownership and health among adults over age 50, using Health and Retirement Study 2010/2012 data to assess cardiometabolic risk levels using biomarkers for inflammation, cardiovascular health, and metabolic function. We find that people living with poor housing conditions and financial strain have higher cardiometabolic risk levels, even taking socioeconomic advantage into account. This analysis sheds light on the housing-related health challenges of older adults, especially older renters.

Education and stroke: evidence from epidemiology and Mendelian randomization study

We aim to characterize the association between education and incident stroke (including total stroke, ischemic stroke, and hemorrhagic stroke) and assess whether there is a causal relationship between them. The final sample size was 11,509 in this study from the Atherosclerosis Risk in Communities (ARIC) study. Cox hazard regression models were used to explore the association between education level and incident stroke. Two-sample Mendelian randomization (MR) was used to estimate the causality. During a median follow-up of 25.3 years, 915 cases (8.0%) of stroke occurred. Participants with advanced education level were associated with 25% (HR 0.75; 95% CI 0.62, 0.91) decreased the rate of incident total stroke. Hazard ratio of intermediate and advanced education level for ischemic stroke were 0.82 (0.69, 0.98) and 0.73 (0.60, 0.90) separately. In the MR analysis, we observed evidence that education was likely a negetive causal risk factor for ischemic stroke (OR 0.764, 95% CI 0.585-0.998, P = 0.048). Higher education level was associated with a decreased rate of total stroke and ischemic stroke incident, but not hemorrhagic stroke incident. There might be a protective causal association between education and ischemic stroke (but not total stroke nor hemorrhagic stroke).

Non-compensatory aggregation method to measure social and material deprivation in an urban area: relationship with premature mortality

Health inequalities exist between nations, regions, and even smaller units. In societies where social and economic structures change rapidly and continuously, analysis of health socioeconomic determinants plays a fundamental role to provide proper policy answers. This study aims to measure accurately two different conceptions of deprivation by developing two different indexes using non-compensatory among sub-indicators aggregation methods. The proposed indicators are compared with premature mortality to verify deprivation's effect on health status. The results show that materially deprived areas are not necessarily socially deprived and vice versa. Material deprivation has a positive statistical co-graduation with premature mortality, while social deprivation has no association with premature mortality.

Trends in stroke incidence among elderly low-income residents of rural China: a population-based study from 1992 to 2016

In China, >70% of stroke deaths occur in people aged ≥65 years. However, trends in the stroke incidence among elderly people are unclear. We aimed to determine trends in the stroke incidence among elderly people in rural China. This was a population-based surveillance study conducted in Tianjin, China. Stroke events and all deaths were registered annually. Trends and annual proportion of change in incidence of first-ever stroke were evaluated from 1992 to 2016. The age-standardized incidence of first-ever stroke increased annually by 3.7% overall in elderly people (2.7% for men; 5.0% for women; all P<0.05). However, from 2008 to 2016, there was no significant change in the trends of stroke incidence among elderly people, across gender and subtypes. The proportion of elderly patients with first-ever stroke decreased by 1.1% annually. In contrast to young patients, annual changes in the incidence of stroke tended to be slight in elderly patients (3.7% vs. 9.5%) with greater increase in female patients than those in male patients (2.7% vs. 10.3% for men; 5.0% vs. 8.9% for women). Thus, the control of risk factors for stroke among elderly people is crucial, especially among older women, to reduce the burden of stroke in China.

Effects of socioeconomic status on risk of ischemic stroke: a case-control study in the Guangzhou population

BACKGROUND

The association between socioeconomic status (SES) and stroke risk remains controversial around the world. It is not clear that the effect of SES on stroke in China due to the lack of relevant research. We aimed to assess the association between SES and risks of first-ever ischemic stroke in Guangzhou, China.

METHODS

Cases were recruited from neurology department in the First Affiliated Hospital of Guangdong Pharmaceutical University during September 2016-October 2017. Age- and sex-matched controls were derived from surgical departments, over the same period. SES was assessed based on education, occupation, and income. Education was divided into ≤6 years, 6-9 years, 10-12 years, and > 12 years. Family monthly income per capita was categorized into ≤¥1000, ¥1001-3000, ¥3001-5000, and > ¥5001. Occupation was stratified into manual, non-manual, no job, and retired. A multivariate logistic regression model was used to determine the association between SES and risk of ischemic stroke.

RESULTS

In total, 347 ischemic stroke patients and 347 controls were recruited, with mean ages of 60.54 ± 13.13 and 60.56 ± 13.07 years, respectively. After adjusting for confounding factors, odds ratio (OR) for 6-9 years of education was 2.63 (95% confidence interval [CI] 1.45-4.75); > 12 years, 2.18 (1.25-3.82) compared with those for < 6 years of education. ORs for the second lowest, third lowest, and highest incomes were 1.96 (1.21-3.15), 4.16 (2.39-7.22), and 2.83(1.25-6.39), respectively, compared with those for the lowest income. ORs for manual workers and non-manual workers were 1.95 (1.23-3.07) and 1.87 (1.05-3.33), compared with individuals without jobs.

CONCLUSIONS

Higher SES is positively related with risks of ischemic stroke, explained by cardiovascular diseases and unhealthy lifestyles in Guangzhou, China. Thus, effective strategies such as extensive health education, promoting a healthy lifestyle, screening for risk factors to prevent stroke should be implemented to reduce ischemic stroke incidences among the high SES group.

Determinants of Developing Stroke Among Low-Income, Rural Residents: A 27-Year Population-Based, Prospective Cohort Study in Northern China

Although strokes are the leading cause of death and disability in many countries, China still lacks long-term monitoring data on stroke incidence and risk factors. This study explored stroke risk factors in a low-income, rural population in China. The study population was derived from the Tianjin Brain Study, a population-based stroke monitoring study that began in 1985. This study documented the demographic characteristics, past medical histories, and personal lifestyles of the study participants. In addition, physical examinations, including measurements of blood pressure (BP), height, and weight, were performed. Hazard ratios (HRs) were estimated for the risk factors for all subtypes of stroke using multivariate Cox regression analyses. During the study with mean following-up time of 23.16 years, 3906 individuals were recruited at baseline, and during 27 years of follow-up, 638 strokes were documented. The multivariate Cox regression analyses revealed a positive correlation between age and stroke incidence. Limited education was associated with a 1.9-fold increase in stroke risk (lowest vs. highest education level). Stroke risk was higher among former smokers than among current smokers (HR, 1.8 vs. 1.6; both, P < 0.05). Moreover, stroke risk was significantly associated with sex (HR, 1.8), former alcohol drinking (HR, 2.7), baseline hypertension (HR, 3.1), and overweight (HR, 1.3). In conclusion, this study identified uncontrollable (sex and age) and controllable (education, smoking, alcohol drinking, hypertension, and overweight) risk factors for stroke in a low-income, rural population in China. Therefore, it is critical to control BP and weight effectively, advocate cessation of smoking/alcohol drinking, and enhance the education level in this population to prevent increase in the burden of stroke in China.

Education, sex and risk of stroke: a prospective cohort study in New South Wales, Australia

OBJECTIVE

To determine whether the association between highest educational attainment and stroke differed by sex and age; and whether potential mediators of observed associations differ by sex.

DESIGN

Prospective cohort study.

SETTING

Population based, New South Wales, Australia.

PARTICIPANTS

253 657 stroke-free participants from the New South Wales 45 and Up Study.

OUTCOME MEASURES

First-ever stroke events, identified through linkage to hospital and mortality records.

RESULTS

During mean follow-up of 4.7 years, 2031 and 1528 strokes occurred among men and women, respectively. Age-standardised stroke rate was inversely associated with education level, with the absolute risk difference between the lowest and highest education group greater among women than men. In relative terms, stroke risk was slightly more pronounced in women than men when comparing low versus high education (age-adjusted HRs: 1.41, 95% CI 1.16 to 1.71 and 1.25, 95% CI 1.07 to 1.46, respectively), but there was no clear evidence of statistical interaction. This association persisted into older age, but attenuated. Much of the increased stroke risk was explained by modifiable lifestyle factors, in both men and women.

CONCLUSION

Low education is associated with increased stroke risk in men and women, and may be marginally steeper in women than men. This disadvantage attenuates but persists into older age, particularly for women. Modifiable risk factors account for much of the excess risk from low education level. Public health policy and governmental decision-making should reflect the importance of education, for both men and women, for positive health throughout the life course.

Education, Socioeconomic Status, and Intelligence in Childhood and Stroke Risk in Later Life: A Meta-analysis

BACKGROUND

Stroke is the second most common cause of death, and a common cause of dependency and dementia. Adult vascular risk factors and socioeconomic status (SES) are associated with increased risk, but less is known about early life risk factors, such as education, childhood SES, or intelligence (IQ).

METHODS

We comprehensively searched Medline, PsycINFO, and EMBASE from inception to November 2015. We included all studies reporting data on >50 strokes examining childhood/premorbid IQ, SES, and education. Two reviewers independently screened full texts and extracted and cross-checked data, including available risk factor adjustments. We meta-analyzed stroke risk using hazard ratios (HR), odds ratios (OR), and mean differences (MD). We tested effects of study and participant characteristics in sensitivity analyses and meta-regression, and assessed heterogeneity and publication bias.

RESULTS

We identified 90 studies examining stroke risk and education (79), SES (10), or IQ (nine) including approximately 164,683 stroke and over 5 million stroke-free participants. Stroke risk increased with lower education (OR = 1.35, 95% CI = 1.24, 1.48), SES (OR = 1.28, 95% CI = 1.12, 1.46), and IQ (HR = 1.17, 95% CI = 1.00, 1.37) in studies reporting point estimates, with similar associations for MD. We found minimal publication bias. Between-study heterogeneity was partly explained by participant age and case ascertainment method.

CONCLUSIONS

Education, childhood SES, and intelligence have modest but important associations with lifetime stroke, and hence dementia, risks. Future studies distinguishing between the individual and combined effects of education, childhood SES and intelligence are needed to determine the independent contribution of each factor to stroke risk. See video abstract at, http://links.lww.com/EDE/B210.

Socioeconomic variation in incidence of primary and secondary major cardiovascular disease events: an Australian population-based prospective cohort study

BACKGROUND

Cardiovascular disease (CVD) disproportionately affects disadvantaged people, but reliable quantitative evidence on socioeconomic variation in CVD incidence in Australia is lacking. This study aimed to quantify socioeconomic variation in rates of primary and secondary CVD events in mid-age and older Australians.

METHODS

Baseline data (2006-2009) from the 45 and Up Study, an Australian cohort involving 267,153 men and women aged ≥ 45, were linked to hospital and death data (to December 2013). Outcomes comprised first event - death or hospital admission - for major CVD combined, as well as myocardial infarction and stroke, in those with and without prior CVD (secondary and primary events, respectively). Cox regression estimated hazard ratios (HRs) for each outcome in relation to education (and income and area-level disadvantage), separately by age group (45-64, 65-79, and ≥ 80 years), adjusting for age and sex, and additional sociodemographic factors.

RESULTS

There were 18,207 primary major CVD events over 1,144,845 years of follow-up (15.9/1000 person-years), and 20,048 secondary events over 260,357 years (77.0/1000 person-years). For both primary and secondary events, incidence increased with decreasing education, with the absolute difference between education groups largest for secondary events. Age-sex adjusted hazard ratios were highest in the 45-64 years group: for major CVDs, HR (no qualifications vs university degree) = 1.62 (95% CI: 1.49-1.77) for primary events, and HR = 1.49 (1.34-1.65) for secondary events; myocardial infarction HR = 2.31 (1.87-2.85) and HR = 2.57 (1.90-3.47) respectively; stroke HR = 1.48 (1.16-1.87) and HR = 1.97 (1.42-2.74) respectively. Similar but attenuated results were seen in older age groups, and with income. For area-level disadvantage, CVD gradients were weak and non-significant in older people (> 64 years).

CONCLUSIONS

Individual-level data are important for quantifying socioeconomic variation in CVD incidence, which is shown to be substantial among both those with and without prior CVD. Findings reinforce the opportunity for, and importance of, primary and secondary prevention and treatment in reducing socioeconomic variation in CVD and consequently the overall burden of CVD morbidity and mortality in Australia.

Explaining socioeconomic inequalities in self-rated health: a systematic review of the relative contribution of material, psychosocial and behavioural factors

BACKGROUND

Material, psychosocial and behavioural factors are important explanatory pathways for socioeconomic inequalities in health. The aim of this systematic review was to summarise the available evidence on empirical studies and to analyse the relative contribution of these factors for explaining inequalities in self-rated health.

METHODS

The study was performed in compliance with PRISMA guidelines. The literature search was conducted in the electronic databases PubMed and Web of Science (1996-2016) as well as by screening of reference lists of obtained articles. Two reviewers performed the search and critical appraisal of the studies. All studies that focus on explaining socioeconomic inequalities in self-rated health, including at least 2 of the 3 main pathways and analysing the relative contribution of these approaches in separate and joint models, were included.

RESULTS

Eleven publications were included. Separate analyses showed that material, psychosocial and behavioural factors contribute to the explanation of socioeconomic inequalities in self-rated health. However, the combined analyses revealed that material factors contributed most to differences in self-rated health because of their higher independent (direct) effect and additional shared (indirect) effect (through psychosocial and behavioural factors). These results were largely independent of age, gender and indicator of socioeconomic status.

CONCLUSIONS

The evidence presented might be used for policymakers to identify and to justify prioritisation in terms of prevention and health promotion. The findings show that multiple factors are important for tackling social inequalities in health. Strategies for reducing these inequalities should focus on material/structural living conditions as they shape conditions of psychosocial resources and health behaviour.

The effects of socioeconomic status on stroke risk and outcomes

The latest evidence on socioeconomic status and stroke shows that stroke not only disproportionately affects low-income and middle-income countries, but also socioeconomically deprived populations within high-income countries. These disparities are reflected not only in risk of stroke but also in short-term and long-term outcomes after stroke. Increased average levels of conventional risk factors (eg, hypertension, hyperlipidaemia, excessive alcohol intake, smoking, obesity, and sedentary lifestyle) in populations with low socioeconomic status account for about half of these effects. In many countries, evidence shows that people with lower socioeconomic status are less likely to receive good-quality acute hospital and rehabilitation care than people with higher socioeconomic status. For clinical practice, better implementation of well established treatments, effective management of risk factors, and equity of access to high-quality acute stroke care and rehabilitation will probably reduce inequality substantially. Overcoming barriers and adapting evidence-based interventions to different countries and health-care settings remains a research priority.

Social class based on occupation is associated with hospitalization for A(H1N1)pdm09 infection. Comparison between hospitalized and ambulatory cases

This study aimed to analyse the existence of an association between social class (categorized by type of occupation) and the occurrence of A(H1N1)pmd09 infection and hospitalization for two seasons (2009-2010 and 2010-2011). This multicentre study compared ambulatory A(H1N1)pmd09 confirmed cases with ambulatory controls to measure risk of infection, and with hospitalized A(H1N1)pmd09 confirmed cases to asses hospitalization risk. Study variables were: age, marital status, tobacco and alcohol use, pregnancy, chronic obstructive pulmonary disease, chronic respiratory failure, cardiovascular disease, diabetes, chronic liver disease, body mass index >40, systemic corticosteroid treatment and influenza vaccination status. Occupation was registered literally and coded into manual and non-manual worker occupational social class groups. A conditional logistic regression analysis was performed. There were 720 hospitalized cases, 996 ambulatory cases and 1062 ambulatory controls included in the study. No relationship between occupational social class and A(H1N1)pmd09 infection was found [adjusted odds ratio (aOR) 0·97, 95% confidence interval (CI) 0·74-1·27], but an association (aOR 1·53, 95% CI 1·01-2·31) between occupational class and hospitalization for A(H1N1)pmd09 was observed. Influenza vaccination was a protective factor for A(H1N1)pmd09 infection (aOR 0·41, 95% CI 0·23-0·73) but not for hospitalization. We conclude that manual workers have the highest risk of hospitalization when infected by influenza than other occupations but they do not have a different probability of being infected by influenza.

Sex differences in trends of incidence and mortality of first-ever stroke in rural Tianjin, China, from 1992 to 2012

BACKGROUND AND PURPOSE

Sex differences in secular trends of stroke incidence are rarely reported. We aimed to explore sex differences in incidence and mortality of stroke in rural China from 1992 to 2012.

METHODS

In 1992, 14 920 residents were recruited to participate in the Tianjin Brain Study, a population-based study on stroke surveillance. Stroke events and all deaths were annually registered.

RESULTS

We observed 908 incident strokes (366 in women) from 1992 to 2012. Women were significantly younger than men (64±12 versus 68±11 years) in 1992 to 1998 (P=0.024). The incidence of first-ever stroke per 100 000 person-years for men was 166 in 1992 to 1998, 227 in 1999 to 2005, and 376 in 2006 to 2012; for women, the rates were 86 (1992-1998), 148 (1999-2005), and 264 (2006-2012). From 1992 to 2012, the incidence grew annually by 5.8% in men and 8.0% in women. The male/female incidence ratio declined significantly: 1.9 in 1992 to 1998, 1.5 in 1999 to 2005, and 1.4 in 2006 to 2012. There were no significant sex differences in mortality. The prevalence of obesity and diabetes mellitus, the levels of total cholesterol and triglycerides, and the age of menopause and reproductive years in women concurrently increased in 2011.

CONCLUSIONS

There was a significant increase in the incidence of first-ever stroke in women annually and a declining trend in the male/female rate ratio in rural China during the past 21 years. These results suggest that stroke will become one of the major diseases affecting women in future decades in China.