Association between annual household income and adverse outcomes in patients who had ischaemic stroke

Mediation Analyses of the Mechanisms by Which Socioeconomic Status, Comorbidity, Stroke Severity, and Acute Care Influence Stroke Outcome

BACKGROUND AND OBJECTIVES

Low socioeconomic status (SES) is associated with increased risk of death and disability after stroke, but interventional targets to minimize disparities remain unclear. We aim to assess the extent to which SES-based disparities in the association between low SES and death and dependency at 3 months after stroke could be eliminated by offsetting differences in comorbidity, stroke severity, and acute care.

METHODS

This nationwide register-based cohort study included all 72 hospitals caring for patients with acute stroke in Sweden. All patients registered with an acute ischemic stroke in the Swedish Stroke Register in 2015-2016 who were independent in activities of daily living (ADL) during stroke were included. Data on survival and SES the year before stroke were retrieved by cross-linkage with other national registers. SES was defined by education and income and categorized into low, mid, and high. Causal mediation analysis was used to study the absolute risk of death and ADL dependency at 3 months depending on SES and to what extent hypothetical interventions on comorbidities, stroke severity, and acute care would equalize outcomes.

RESULTS

Of the 25,846 patients in the study, 6,798 (26.3%) were dead or ADL dependent 3 months after stroke. Adjusted for sex and age, low SES was associated with an increased absolute risk of 5.4% (95% CI 3.9%-6.9%; p < 0.001) compared with mid SES and 10.1% (95% CI 8.1%-12.2%; p < 0.001) compared with high SES. Intervening to shift the distribution of all mediators among patients with low SES to those of the more privileged groups would result in absolute reductions of these effects by 2.2% (95% CI 1.2%-3.2%; p < 0.001) and 4.0% (95% CI 2.6%-5.5%; p < 0.001), respectively, with the largest reduction accomplished by equalizing stroke severity.

DISCUSSION

Low SES patients have substantially increased risks of death and ADL dependency 3 months after stroke compared with more privileged patient groups. This study suggests that if we could intervene to equalize SES-related differences in the distributions of comorbidity, acute care, and stroke severity, up to 40 of every 1,000 patients with low SES could be prevented from dying or becoming ADL dependent.

Associations between socioeconomic status and stroke in American adults: A population-based study

Stroke is an acute cerebrovascular disease that can lead to disability and death. This study aimed to investigate the relationship between socioeconomic status (SES) and stroke. SES was evaluated by two variables: poverty to income ratio (PIR) and education level. In this multi-subject study, we collected data from the National Health and Nutrition Examination Survey (NHANES) database between 2009 and 2018, and finally 22,792 adults (≥20 years old) were included in the study. We proceeded with weighted multivariate logistic regression analysis as well as subgroup analysis. When analyzing the effect of PIR on stroke alone, the results showed that an increase in PIR levels was associated with a decrease in stroke incidence (OR = 0.764 95% CI: (0.711, 0.820), p < 0.001). The multivariate analysis presented a decline in stroke incidence in the highest quartile PIR group compared to the lowest quartile PIR group (OR = 0.296 95% CI: (0.214, 0.409), P＜0.001). Our results indicated that PIR is a protective factor for stroke, but there are exceptions in this relationship among different people. Hence, it is imperative that policymakers, healthcare providers, and clinicians take into account the inequality distribution of SES among adults while developing and executing stroke prevention and treatment strategies.

Socioeconomic Inequalities in Functional Outcome After Reperfusion-Treated Ischemic Stroke

BACKGROUND

We aimed to investigate whether socioeconomic status (SES) was associated with functional outcome in patients with ischemic stroke treated with reperfusion therapy (intravenous thrombolysis and/or thrombectomy).

METHODS

This nationwide cohort study included reperfusion-treated patients with ischemic stroke ≥18 years registered in the Danish Stroke Registry between 2015 and 2018. Functional outcome was determined by the modified Rankin Scale score 90 days after stroke. SES was defined by educational attainment, family income, and employment status before stroke. SES data were available from Statistics Denmark and linked on the individual level with data from the Danish Stroke Registry. Uni- and multivariable ordinal logistic regression was performed for each socioeconomic parameter individually (education, income, and employment) to estimate the common odds ratios (cORs) for lower 90-day modified Rankin Scale scores.

RESULTS

A total of 5666 patients were included. Mean age was 68.7 years (95% CI, 68.3-69.0), and 38.4% were female. Low SES was associated with lower odds for achieving lower 90-day modified Rankin Scale score: Low versus high education, cOR, 0.69 (95% CI, 0.61-0.79), low versus high income, cOR, 0.59 (95% CI, 0.53-0.67), and unemployed versus employed, cOR, 0.70 (95% CI, 0.58-0.83). Inequalities were reduced after adjusting for age, sex, and immigrant status, except for unemployed versus employed patients, adjusted cOR, 0.66 (95% CI, 0.54-0.80). No statistically significant differences remained after adjusting for potentially mediating variables (eg, stroke severity, prestroke modified Rankin Scale, and smoking).

CONCLUSIONS

Socioeconomic inequalities were observed in functional outcome after reperfusion treated ischemic stroke. In particular, prestroke unemployment was negatively associated with good functional outcome. A more adverse prognostic profile among patients with low SES appeared to explain the majority of these inequalities.

Dissecting the causal relationship between household income status and genetic susceptibility to cardiovascular-related diseases: Insights from bidirectional mendelian randomization study

OBJECTIVES

Observational studies have revealed that socioeconomic status is associated with cardiovascular health. However, the potential causal effect remains unclear. Hence, we aimed to investigate the causal relationship between household income status and genetic susceptibility to cardiovascular-related diseases using a bidirectional Mendelian randomization (MR) study.

METHODS

An MR study based on a large-sample cohort of the European population from a publicly available genome-wide association study datasets was conducted using a random-effects inverse-variance weighting model as the main standard. Simultaneously, MR-Egger regression, weighted median, and maximum likelihood estimation were used as supplements. Sensitivity analysis, consisting of a heterogeneity test and horizontal pleiotropy test, was performed using Cochran's Q, MR-Egger intercept, and MR-PRESSO tests to ensure the reliability of the conclusion.

RESULTS

The results suggested that higher household income tended to lower the risk of genetic susceptibility to myocardial infarction (OR: 0.503, 95% CI = 0.405-0.625, P < 0.001), hypertension (OR: 0.667, 95% CI = 0.522-0.851, P = 0.001), coronary artery disease (OR: 0.674, 95% CI = 0.509-0.893, P = 0.005), type 2 diabetes (OR: 0.642, 95% CI = 0.464-0.889, P = 0.007), heart failure (OR: 0.825, 95% CI = 0.709-0.960, P = 0.013), and ischemic stroke (OR: 0.801, 95% CI = 0.662-0.968, P = 0.022). In contrast, no association was evident with atrial fibrillation (OR: 0.970, 95% CI = 0.767-1.226, P = 0.798). The reverse MR study suggested a potentially negative trend between heart failure and household income status. A sensitivity analysis verified the reliability of the results.

CONCLUSIONS

The results revealed that the population with higher household income tended to have a lower risk of genetic susceptibility to myocardial infarction and hypertension.