Non-linear dose-response relationship between body mass index and stroke risk in middle-aged and elderly Chinese men: a nationwide Longitudinal Cohort Study from CHARLS

Joint association of estimated glucose disposal rate and body mass index with new-onset stroke

Background

Stroke is a major global health concern, and understanding its modifiable risk factors is critical for prevention. Body mass index (BMI) and estimated glucose disposal rate (eGDR), indicators of adiposity and insulin sensitivity, respectively, are independently associated with stroke risk. However, the combined effects of these factors remain underexplored.

Methods

This study utilized data from the China Health and Retirement Longitudinal Study (CHARLS), including 7,212 adults aged over 45 years. Cox proportional hazards models assessed the independent and joint associations of BMI and eGDR with new-onset stroke. Mediation analysis evaluated BMI's role in the eGDR-stroke relationship. Subgroup analyses by age, sex, and BMI categories were conducted.

Results

Over a 7-year follow-up, 587 participants (8.14%) experienced new-onset stroke. Higher BMI was positively associated with stroke incidence, while lower eGDR was linked to increased stroke risk. Participants with both obesity (BMI over 28 kg/m2) and lower eGDR faced the highest stroke risk (HR: 2.63; 95% CI: 1.78-3.89). Mediation analysis revealed that BMI significantly mediated 16.78% of the association between eGDR and new-onset stroke. Subgroup analyses showed consistent associations across age, sex, and BMI categories.

Conclusion

This study highlights the significant and interconnected roles of BMI and eGDR in new-onset stroke risk, with a compounding effect observed in individuals with obesity and low eGDR. Addressing both insulin resistance and adiposity through targeted interventions could effectively reduce stroke risk, particularly in high-risk populations.

Association between BMI and asthma in adults over 45 years of age: analysis of Global Burden of Disease 2021, China Health and Retirement Longitudinal Study, and National Health and Nutrition Examination Survey data

Background

Asthma is a major global health concern, and body mass index (BMI) is a key risk factor. This study aims to investigate the potential nonlinear relationship between BMI and asthma risk in populations over 45 years of age using large-scale, cross-national data.

Methods

This cross-sectional study utilised three databases: GBD 2021, China Health and Retirement Longitudinal Study (CHARLS; cross-sectional data from baseline survey, January 01, 2011 to December 31, 2011), and National Health and Nutrition Examination Survey (NHANES; cross-sectional data from 2011 to 2012 cycle). Participants aged ≥45 years after excluding those with missing data on BMI, asthma history, smoking history, age, sex, and BMI outside 10-80 kg/m2 were included. Asthma was defined by self-report in CHARLS and by physician diagnosis plus recent symptoms in NHANES. Smooth curve fitting was performed to visualise the BMI-asthma relationship, adjusting for multiple confounders. We applied segmented regression models to identify potential threshold effects, used likelihood ratio tests to compare linear and non-linear models, and employed bootstrap resampling for confidence intervals.

Findings

High BMI was the primary risk factor for asthma-related DALYs globally (14.93% in 2021). From CHARLS, we included 13,393 participants, comprising 6267 males (46.79%) and 7126 females (53.21%). From NHANES, we included 2925 participants, comprising 46.6% males and 53.4% females. CHARLS data revealed a U-shaped relationship between BMI and asthma risk, with critical points at 19.9 kg/m2 and 29.9 kg/m2. For BMI < 19.9 kg/m2, asthma risk increased by 28% with each unit decrease in BMI (OR = 1.28, 95% CI: 1.15-1.43). For BMI ≥ 29.9 kg/m2, asthma risk increased by 25% with each unit increase in BMI (OR = 1.25, 95% CI: 1.05-1.49). NHANES data showed a non-linear relationship with a turning point at 21.6 kg/m2. For BMI ≥ 21.6 kg/m2, asthma risk increased by 5% with each unit increase in BMI (OR = 1.05, 95% CI: 1.03-1.06).

Interpretation

This study elucidates a significant non-linear relationship between BMI and asthma risk in populations aged 45 years and older, providing insights for tailored asthma prevention strategies, although the cross-sectional design limits causal inference. Future studies should focus on collecting and stratifying longitudinal data and adjusting for asthma diagnosis timing to obtain more accurate results.

Funding

National Nature Science Foundation of China.

Association between the hemoglobin A1c/High-density lipoprotein cholesterol ratio and stroke incidence: a prospective nationwide cohort study in China

BACKGROUND

Stroke has emerged as an escalating public health challenge among middle-aged and older individuals in China, closely linked to glycolipid metabolic abnormalities. The Hemoglobin A1c/High-Density Lipoprotein Cholesterol (HbA1c/HDL-C) ratio, an integrated marker of glycolipid homeostasis, may serve as a novel predictor of stroke risk.

METHODS

Our investigation utilized data from the China Health and Retirement Longitudinal Study cohort (2011-2018). Stroke cases were identified based on self-reported, physician-confirmed diagnoses. Logistic regression models were established to determine the correlation between HbA1c/HDL-C and stroke prevalence (2011) as well as between cumulative mean HbA1c/HDL-C (2011-2015) and new stroke incidence (2015-2018). Additionally, smoothed curve fitting, subgroup analyses, and interaction tests were conducted to ensure the robustness of the findings.

RESULTS

In the cross-sectional analysis, 8,502 participants were enrolled, of whom 189 had a history of stroke. Our findings revealed a significant positive linear relationship between HbA1c/HDL-C and stroke prevalence after adjusting for covariates (OR: 1.26, 95% CI: 1.09-1.45). When HbA1c/HDL-C was categorized into tertiles, only the highest tertile (T3) showed a significant correlation with stroke prevalence compared to the lowest tertile (T1) (OR:1.71, 95% CI: 1.05-2.77). In the longitudinal analysis of 5,165 participants, 336 cases of new-onset stroke were identified over a follow-up period of 7 years. Adjusting for confounders, individuals with higher cumulative mean HbA1c/HDL-C exhibited an increased likelihood of new stroke incidence (OR: 1.14, 95% CI: 1.01-1.29). Using the T1 of cumulative mean HbA1c/HDL-C as a reference, the fully adjusted OR for stroke was 1.65 (95% CI: 1.21-2.24) in T2 and 1.54 (95% CI: 1.08-2.19) in T3. The predictive value of the HbA1c/HDL-C in stroke risk assessment have been significantly improved compared to the traditional HDL-C and HbA1c. Consistent associations were observed across most stratified subgroups.

CONCLUSIONS

Elevated baseline and cumulative mean HbA1c/HDL-C levels are significantly associated with an increased risk of stroke among middle-aged and older individuals in China, underscoring the potential of HbA1c/HDL-C as a clinical marker for long-term stroke risk assessment and prevention strategies.

Green space is associated with new-onset stroke among Chinese middle-aged and older adults: data from China Health and Retirement Longitudinal Study (CHARLS)

Background and aims

The relationship between green space and new-onset stroke is inconclusive. This study aimed to investigate the association between green space and stroke risk among Chinese middle-aged and older adults.

Methods

Data were taken from participants aged ≥45 years in the China Health and Retirement Longitudinal Study (CHARLS). Baseline data were collected in 2011 and new-onset stroke data were gathered during follow-up in 2013, 2015, 2018, and 2020. Multivariate Cox regression models were constructed to investigate the association between green space and stroke risk. Subgroup analysis was also performed.

Results

A total of 13,696 participants with a mean age of 59.3 ± 9.3 years were included. After a mean follow-up duration of 6.32 years, there were 728 stroke events during a total of 86,530 person-years of follow-up. The study found a L-shaped relationship between green space and the risk of new-onset stroke in participants. By using a two-piecewise linear regression model, we calculated that the inflection point for the per capita park green area was 10.61 square meters per person (log-likelihood ratio test p = 0.041). On the left of the inflection point, we observed a negative relationship between green space and the incidence of stroke (HR: 0.89, 95% CI: 0.84-0.94, p = 0.0001). On the right side of the inflection point, however, the relationship tended to be saturated (HR: 0.97, 95% CI: 0.94-1.01, p = 0.2111).

Conclusion

Our study found that the relationship between green space and the risk of new-onset stroke follows a L-shaped curve. A lower amount of green space is associated with an increased risk of new-onset stroke. These findings require confirmation in future studies.

The Impact of Insulin Resistance on the Development of Post-PCI Contrast-Induced Nephropathy in Non-Diabetic STEMI

Aims

Contrast-induced nephropathy (CIN) is a condition characterized by rapidly decreasing renal funciton following by the application of contrast material. Precutaneous coronary intervention (PCI) is a life-saving treatment method that should be applied under emergent conditions. Unfortunately, the incidence of CIN after PCI is common. Patients with insulin resistance or diabetes have a greater risk of developing CIN than most of the population. Therefore, studies on the predictive effects of insulin resistance indicators on CIN are gaining momentum. One of the most popular indicators is triglyceride/glucose-body mass index (TyG-BMI). In this study we aimed to evaluate the effect of TyG-BMI index on CIN.

Materials and Methods

A total of 960 patinets who underwent emergency PCI due to ST elevation myocardial infarction (STEMI) between 2020 and 2023 were included in the study. Laboratory and demographic parameters were compared between the patients who did and did not develop CIN.

Results

While CIN developed in 120 of the 980 patients included in the study, it did not develop in 860 patients. There were significant differences between the groups in terms of age (p < 0.001), gender (p = 0.005), presence of hypertension (p = 0.021), heart rate (p = 0.049), amount of contrast material (p < 0.001), left ventricular ejection fraction (p < 0.001), stent length (p = 0.022), SYNTAX score (p < 0.001), fasting plasma glucose (p < 0.001), baseline creatinine (p < 0.001), glomerular filtration rate (p < 0.001), uric acid (p < 0.001), C reactive protein (CRP) (p < 0.001), baseline creatin kinase myocard band (CKMB) (p = 0.019), CKMB peak (p = 0.030), triglyceride (p = 0.017), and TyG-BMI (p < 0.001). CRP, creatinine, uric asid, amount of contrast material, and TyG-BMI were independent predictors for the development of CIN.

Conclusions

TyG-BMI was a predictor of CIN in STEMI patient who underwent PCI under emergency conditions. In addition, the predicitive power of TyG-BMI was stronger than triglyceride-glucose index.

Prevalence and risk factors of headache in Chinese with stroke: a cross-sectional study based on CHARLS

BACKGROUND

Stroke ranks as the second leading cause of death worldwide. Meanwhile, headaches are considered the second leading cause of disability, and they often occur as a stroke complication. However, insufficient attention has been given to the treatment and rehabilitation of headaches among stroke patients, and the research on the epidemiology and risk factors of headaches in stroke patients in China is limited. Therefore, in this study, China Health and Retirement Longitudinal Study (CHARLS) data were utilized for a cross-sectional analysis to estimate the prevalence of headaches in stroke patients and identify the associated risk factors.

METHOD

This study utilized data, which included those of participants aged 45 and above from 28 provinces across China, from the nationally representative CHARLS 2018 database. A total of 876 stroke patients and 17,469 nonstroke patients were considered in this work. Stroke diagnosis and headache status were determined based on self-reported questionnaire responses. Cross-sectional analysis determined the prevalence of headaches in patients with strokes and those without through quantification of individuals diagnosed with headaches. Categorical variables were presented as percentages and counts, and univariate and multivariate logistic regression models were used to calculate the odds ratios (OR) for the risk factors associated with headaches in stroke patients.

RESULTS

In the 2018 data, 328 individuals with stroke-related headaches were screened and compared with 4,249 individuals without the condition. Overall, a cross-sectional survey revealed that the headache prevalence among stroke patients reached 37.44% (95% confidence interval (CI): 34.23%-40.74%), which was higher than the overall headache prevalence among nonstroke patients 24.32% (95% CI: 23.69%-24.97%). Headaches were considerably more common in women (45.95%; 95% CI: 41.31%-50.58%) than in men (26.70%; 95% CI: 24.44%-32.97%; gender difference, p < 0.001). According to multifactorial logistic regression analysis, the risk factors for stroke-related headaches included being female (OR: 1.45, 95% CI: 1.02-2.07), residency in Central (2.50, 1.37-4.54), Eastern (1.87, 1.07-3.27), and Northwest China (2.49, 1.06-5.84), Very poor self-health (4.06, 1.90-8.68), diabetes (1.85, 1.11-3.07), shoulder pain (4.01, 2.77-5.81), back pain (2.01, 1.32-3.05), and chest pain (2.51, 1.55-4.06).

CONCLUSION

Enhancement of self-awareness of health, effective management of diabetes, and minimization of the physical discomfort in the shoulders, back, and chest may contribute to the decreased occurrence of headaches. Therefore, targeted prevention and treatment of headaches are necessary.

Triglyceride-glucose index mediates the association between residual cholesterol and stroke among middle-aged and older adults in China: a prospective, nationwide, population-based study

Background

Both triglyceride-glucose (TyG) index and residual cholesterol (RC) are predictors of stroke; however, to what extent the RC is associated with stroke through TyG index is unclear. This study examined whether the TyG index mediates the association of RC with incident stroke and the extent of interaction or joint relations of RC and TyG index with stroke in middle-aged and older Chinese adults.

Methods

This is an ongoing prospective cohort study initiated in 2011 that included 10,569 middle-aged and older Chinese adults without stroke at baseline. The exposure was RC, the mediator was TyG index, and the outcome was stroke which followed up from June, 2011, to June, 2018. Mediation analysis was used to explore whether the TyG index mediated the association between RC and stroke risk.

Results

Of the 10,569 participants, 4,978 (47.1%) were men; the mean (SD) age was 59.01 (9.43) years. During a median follow-up of 7.1 years, 734 (7.0%) participants experienced a stroke. In the adjusted Cox models, A one SD increase in RC was associated with an elevated risk of stroke (HR, 1.09; 95% CI, 1.02-1.16), as well as TyG index (HR, 1.14; 95% CI, 1.06-1.23). No significant multiplicative or additive interactions were found between the TyG index and RC on stroke risk (HR for multiplicative: 1.07, 95% CI, 0.67-1.70; Synergy index: 1.05, 95% CI, 0.16-6.88). TyG index mediated the association between RC and stroke (b, -0.16; 95% CI, -0.30 to -0.03). Subgroup analyses and sensitivity analyses showed consistent results.

Conclusions

This study evidence that the TyG index completely mediates the association between RC and stroke risk among middle-aged and older Chinese adults. These findings highlight the importance of considering RC and the TyG index in stroke risk assessment.

Association between platelet-to-high-density lipoprotein cholesterol ratio and future stroke risk: a national cohort study based on CHARLS

Background

According to recent research, there is a considerable correlation between the severity of coronary artery disease and the platelet-to-high-density lipoprotein cholesterol ratio (PHR), which suggests that PHR is a potentially valuable inflammatory biomarker. However, the body of current research offers insufficiently strong evidence to clarify the connection between PHR and the incidence of stroke. Therefore, this study aims to elucidate any potential associations between PHR and stroke risk.

Methods

This study employed data from the China Health and Retirement Longitudinal Study (CHARLS) covering the period from 2011 to 2018. It included 5,872 participants who did not have a history of stroke in 2011. These patients were separated into four groups according to their baseline PHR quartiles. The main goal of the study was to focus on stroke outcomes. Stroke was defined as an occurrence of a cerebrovascular accident confirmed by a physician. We employed Cox proportional hazards regression models to investigate the association between PHR and the likelihood of experiencing a stroke. Furthermore, we conducted restricted cubic spline regression analysis and subgroup analysis.

Results

The average follow-up period was 77.5 months, during which 390 participants experienced a stroke. In comparison to the lowest quartile group, participants in the highest quartile of PHR had a 49% increased risk of stroke (HR 1.49, 95% CI 1.13-1.96, p = 0.004). The adjusted multivariable Cox regression analysis maintained the statistical significance of this association (aHR 1.42, 95% CI 1.06-1.90, p = 0.019). After adjustment, a positive linear relationship between stroke risk and PHR was identified through restricted cubic spline regression analysis (nonlinear p > 0.05). Additionally, the impact of stroke was consistent across a variety of subgroups, as evidenced by subgroup analysis.

Conclusion

Our study indicates that higher PHR levels are significantly associated with an increased risk of stroke and that these levels can be used to identify groups that are at high risk of stroke.

A non-linear connection between the total cholesterol to high-density lipoprotein cholesterol ratio and stroke risk: a retrospective cohort study from the China Health and Retirement Longitudinal Study

OBJECTIVE

The connection between total cholesterol to high-density lipoprotein cholesterol (TC/HDL-C) ratio and stroke risk is controversial. This study aims to examine the connection between the TC/HDL-C ratio and stroke in middle-aged and older individuals who are part of the China Health and Retirement Longitudinal Study (CHARLS).

METHODS

This study conducted a retrospective cohort analysis, enrolling a total of 10,184 participants who met the designated criteria from CHARLS between 2011 and 2012. We then used the Cox proportional-hazards regression model to analyze the relationship between the TC/HDL-C ratio and stroke risk. Using a Cox proportional hazards regression model with cubic spline functions and smooth curve fitting, we were able to identify the non-linear relationship between the TC/HDL-C ratio and stroke occurrence. The sensitivity and subgroup analyses were also performed to investigate the connection between TC/HDL-C ratio and stroke.

RESULTS

This study revealed a statistically significant association between the TC/HDL-C ratio and stroke risk in subjects aged 45 years or older after adjusting for risk factors (HR: 1.05, 95%CI 1.00-1.10, P = 0.0410). Furthermore, a non-linear connection between the TC/HDL-C ratio and stroke risk was detected, with a TC/HDL-C ratio inflection point of 3.71. We identified a significant positive connection between the TC/HDL-C ratio and stroke risk, when the TC/HDL-C ratio was less than 3.71 (HR: 1.25, 95%CI 1.07-1.45, P = 0.0039). However, their connection was not significant when the TC/HDL-C ratio exceeded 3.71 (HR: 1.00, 95%CI 0.94-1.06, P = 0.9232). The sensitivity analysis and subgroup analyses revealed that our findings were well-robust.

CONCLUSION

Our study demonstrated a positive, non-linear connection between the TC/HDL-C ratio and stroke risk in middle-aged and older individuals. There was a significant positive connection between the TC/HDL-C ratio and stroke risk, when the TC/HDL-C ratio was less than 3.71. The current research can be used as a guideline to support clinician consultation and optimize stroke prevention measures for middle-aged and older adults.

Link between triglyceride-glucose-body mass index and future stroke risk in middle-aged and elderly chinese: a nationwide prospective cohort study

OBJECTIVE

Current literature is deficient in robust evidence delineating the correlation between the triglyceride glucose-body mass index (TyG-BMI) and the incidence of stroke. Consequently, this investigation seeks to elucidate the potential link between TyG-BMI and stroke risk in a cohort of middle-aged and senior Chinese individuals.

METHODS

This study employs longitudinal data from four waves of the China Health and Retirement Longitudinal Study (CHARLS) conducted in 2011, 2013, 2015, and 2018, encompassing 8,698 participants. The CHARLS cohort was assembled using a multistage probability sampling technique. Participants underwent comprehensive evaluations through standardized questionnaires administered via face-to-face interviews. Our analytic strategy involved the application of Cox proportional hazards regression models to investigate the association between TyG-BMI and the risk of stroke. To discern potential non-linear relationships, we incorporated Cox proportional hazards regression with smooth curve fitting. Additionally, we executed a battery of sensitivity and subgroup analyses to validate the robustness of our findings.

RESULTS

Our study utilized a multivariate Cox proportional hazards regression model and found a significant correlation between the TyG-BMI and the risk of stroke. Specifically, a 10-unit increase in TyG-BMI corresponded to a 4.9% heightened risk of stroke (HR = 1.049, 95% CI 1.029-1.069). The analysis also uncovered a non-linear pattern in this relationship, pinpointed by an inflection point at a TyG-BMI value of 174.63. To the left of this inflection point-meaning at lower TyG-BMI values-a 10-unit hike in TyG-BMI was linked to a more substantial 14.4% rise in stroke risk (HR 1.144; 95% CI 1.044-1.253). Conversely, to the right of the inflection point-at higher TyG-BMI values-each 10-unit increment was associated with a smaller, 3.8% increase in the risk of stroke (HR 1.038; 95% CI 1.016-1.061).

CONCLUSIONS

In the middle-aged and elderly Chinese population, elevated TyG-BMI was significantly and positively associated with stroke risk. In addition, there was also a specific non-linear association between TyG-BMI and stroke (inflection point 174.63). Further reduction of TyG-BMI below 174.63 through lifestyle changes and dietary control can significantly reduce the risk of stroke.

Exercise Effects on Health-Related Quality of Life (HRQOL), Muscular Function, Cardiorespiratory Function, and Body Composition in Smokers: A Narrative Review

Smoking is amongst the leading global threats with high incidences of preventable premature mortality, morbidity, and various chronic diseases. The World Health Organization (WHO) proclaims a decrease in the prevalence of daily smoking in both males and females from 1980 to 2012, however, the number of regular smokers since then has exponentially increased. The low socio-income status individuals contribute greatly towards tobacco-attributable diseases due to limited access to healthcare systems, mostly in developing countries as compared to developed countries. Smoking affects the optimal functioning of the human body, which results in altered body system processes. Although a high intake of nicotine can lead to prolonged adherence and dependence on smoking, other factors, such as an individual's level of health-related quality of life (HRQOL), stress, depression, and anxiety, can produce similar effects. Smoking has a wide impact on lifestyle factors, which explains the increase in the number of sedentary smokers with decreased health fitness levels and poor lifestyle conditions. Therefore, this study seeks to investigate the exercise effects on health-related quality of life (HRQOL), muscular function, cardiorespiratory function, and body composition in smokers. Concurrently, exercise as an intervention has been sourced as a rehabilitation strategy during smoking cessation programmes to restore the diminishing health components, however, a high rate of relapse occurs due to intolerable withdrawal symptoms.