Mild-to-Moderate Kidney Dysfunction and Cardiovascular Disease: Observational and Mendelian Randomization Analyses

Recent advances in the application of Mendelian randomization to chronic kidney disease

OBJECTIVE

Chronic kidney disease (CKD) is a condition influenced by both genetic and environmental factors and has been a focus of extensive research. Utilizing Mendelian randomization, researchers have begun to untangle the complex causal relationships underlying CKD. This review delves into the advances and challenges in the application of MR in the field of nephrology, shifting from a mere summary of its principles and limitations to a more nuanced exploration of its contributions to our understanding of CKD.

METHODS

Key findings from recent studies have been pivotal in reshaping our comprehension of CKD. Notably, evidence indicates that elevated testosterone levels may impair renal function, while higher sex hormone-binding globulin (SHBG) levels appear to be protective, predominantly in men. Surprisingly, variations in plasma glucose and glycated hemoglobin levels seem unaffected by genetically induced changes in the estimated glomerular filtration rate (eGFR), suggesting an independent pathway for renal function impairment.

RESULTS

Furthermore, lifestyle factors such as physical activity and socioeconomic status emerge as significant influencers of CKD risk and kidney health. The relationship between sleep duration and CKD is nuanced; short sleep duration is linked to increased risk, while long sleep duration does not exhibit a clear causal effect. Additionally, lifestyle factors, including diet, exercise, and mental wellness activities, play a crucial role in kidney health. New insights also reveal a substantial causal connection between both central and general obesity and CKD onset, while no significant links were found between genetically modified LDL cholesterol or triglyceride levels and kidney function.

CONCLUSION

This review not only presents the recent achievements of MR in CKD research but also illuminates the path forwards, underscoring critical unanswered questions and proposing future research directions in this dynamic field.

Cross-sectional studies of the causal link between asthma and osteoporosis: insights from Mendelian randomization and bioinformatics analysis

The study, using data from Chongqing, China, and employing Mendelian randomization along with bioinformatics, establishes a causal link between asthma and osteoporosis, beyond glucocorticoid effects. Asthma may contribute to osteoporosis by accelerating bone turnover through inflammatory factors, disrupting the coupling between osteoblasts and osteoclasts, ultimately leading to osteoporosis.

INTRODUCTION

Asthma and osteoporosis are prevalent health conditions with substantial public health implications. However, their potential interplay and the underlying mechanisms have not been fully elucidated. Previous research has primarily focused on the impact of glucocorticoids on osteoporosis, often overlooking the role of asthma itself.

METHODS

We conducted a multi-stage stratified random sampling in Chongqing, China and excluded individuals with a history of glucocorticoid use. Participants underwent comprehensive health examinations, and their clinical data, including asthma status, were recorded. Logistic regression and Mendelian randomization were employed to investigate the causal link between asthma and osteoporosis. Furthermore, bioinformatics analyses and serum biomarker assessments were conducted to explore potential mechanistic pathways.

RESULTS

We found a significant association between asthma and osteoporosis, suggesting a potential causal link. Mendelian Randomization analysis provided further support for this causal link. Bioinformatics analyses revealed that several molecular pathways might mediate the impact of asthma on bone health. Serum alkaline phosphatase levels were significantly elevated in the asthma group, suggesting potential involvement in bone turnover.

CONCLUSION

Our study confirms a causal link between asthma and osteoporosis and highlights the importance of considering asthma in osteoporosis prediction models. It also suggests that asthma may accelerate osteoporosis by increasing bone turnover through inflammatory factors, disrupting the coupling between osteoblasts and osteoclasts, ultimately leading to bone loss.

Proteinuria and risk of ocular motor cranial nerve palsy: a nationwide population-based study

Understanding the association between dipstick-detected proteinuria and oculomotor cranial nerve palsy (CNP) could have significant implications for understanding the mechanism of CNP development and for developing preventive strategies against CNP development in patients with proteinuria. This study aimed to determine the relationship between dipstick-determined proteinuria and ocular motor CNP using National Sample Cohort (NSC) database from Korea's National Health Insurance Service (NHIS). A nationwide population-based cohort study was conducted using data from the NSC database of Korea's NHIS. These data were collected from 2009 to 2018. A one-year time lag was established to prevent a situation in which the causal link was inverted. Participants aged 20 years or more who were diagnosed with proteinuria in 2009 were included. Individuals with specific pre-existing CNP, missing data, and those who were newly diagnosed with CNP or who died within one year of being tested were excluded. The study population was classified into six groups according to the degree of proteinuria (negative, trace, or between 1 + and 4 +) based on the urine dipstick test. A Cox proportional hazard regression analysis was performed to determine the linkage between the degree of proteinuria and ocular motor CNP. A total of 5,807 (0.14% of subjects) with ocular motor CNP were assigned to the ocular motor CNP group and 4,047,205 subjects were assigned to the control group. After full adjustment of comorbidities, hazard ratios (HRs) for 1 + , 2 + , 3 + and 4 + proteinuria groups were 1.449 (95% confidence interval [CI] 1.244-1.687), 2.081 (1.707-2.538), 1.96 (1.322-2.904), and 3.011 (1.507-6.014), respectively, for developing ocular motor CNP compared to the proteinuria-negative group. In subgroup analysis, the HR of patients with proteinuria for the development of ocular motor CNP was higher in the younger age group (less than 40 years) (P = 0.0242) and the group with DM (P = 0.04). Our population-based cohort study demonstrated a significant association between proteinuria and the incidence of CNP, suggesting that urine protein level could be a new clinical marker for predicting the development of CNP.

Aortic Stenosis and Renal Function: A Bidirectional Mendelian Randomization Analysis

BACKGROUND

Large observational studies have demonstrated a clear inverse association between renal function and risk of aortic stenosis (AS). Whether this represents a causal, reverse causal or correlative relationship remains unclear. We investigated this using a bidirectional 2-sample Mendelian randomization approach.

METHODS AND RESULTS

We collected summary statistics for the primary analysis of chronic kidney disease (CKD) and AS from genome-wide association study meta-analyses including 480 698 and 653 867 participants, respectively. We collected further genome-wide association study summary statistics from up to 1 004 040 participants for sensitivity analyses involving estimated glomerular filtration rate (eGFR) derived from creatinine, eGFR derived from cystatin C, and serum urea nitrogen. Inverse-variance weighted was the primary analysis method, with weighted-median, weighted-mode, Mendelian randomization-Egger, and Mendelian randomization-Pleiotropy Residual Sum and Outlier as sensitivity analyses. We did not find evidence of a causal relationship between genetically predicted CKD liability as the exposure and AS as the outcome (odds ratio [OR], 0.94 per unit increase in log odds of genetic liability to CKD [95% CI, 0.85-1.04], P=0.26) nor robust evidence of AS liability as the exposure and CKD as the outcome (OR, 1.04 per unit increase in log odds of genetic liability to AS [95% CI, 0.97-1.12], P=0.30). The sensitivity analyses were neutral overall, as were the analyses using eGFR derived from creatinine, eGFR derived from cystatin C, and serum urea nitrogen. All positive controls demonstrated strong significant associations.

CONCLUSIONS

The present study did not find evidence of a substantial effect of genetically predicted renal impairment on risk of AS. This has important implications for research efforts that attempt to identify prevention and treatment targets for both CKD and AS.

Nonlinear relationship between high-density lipoprotein cholesterol and cardiovascular disease: an observational and Mendelian randomization analysis

BACKGROUND

Clinical trials and Mendelian randomization (MR) studies reported null effects of high-density lipoprotein cholesterol (HDL-C) on risk of cardiovascular disease (CVD), which might have overlooked a nonlinear causal association. We aimed to investigate the dose-response relationship between circulating HDL-C concentrations and CVD in observational and MR frameworks.

METHODS

We included 348,636 participants (52,919 CVD cases and 295,717 non-cases) of European ancestry with genetic data from the UK Biobank (UKB) and acquired genome-wide association summary data for HDL-C of Europeans from the Global Lipids Genetics Consortium (GLGC). Observational analyses were conducted in the UKB. Stratified MR analyses were conducted combing genetic data for CVD from UKB and lipids from GLGC.

RESULTS

Observational analyses showed L-shaped associations of HDL-C with CVD, with no further risk reduction when HDL-C levels exceeded 70 mg/dL. Multivariable MR analyses across entire distribution of HDL-C found no association of HDL-C with CVD, after control of the pleiotropic effect on other lipids and unmeasured pleiotropism. However, in stratified MR analyses, significant inverse associations of HDL-C with CVD were observed in the stratum of participants with HDL-C ≤ 50 mg/dL (odds ratio per unit increase, 0.86; 95 % confidence interval, 0.79-0.94), while null associations were observed in any stratum above 50 mg/dL.

CONCLUSIONS

Our data suggest a potentially causal inverse association of HDL-C at low levels with CVD risks. These findings advance our knowledge about the role of HDL as a potential target in CVD prevention and therapy.

Cardiovascular and renal outcomes with varying degrees of kidney disease in high-risk people with type 2 diabetes: An epidemiological analysis of data from the AMPLITUDE-O trial

AIMS

To estimate the incidence of a major adverse cardiovascular event (MACE) and a composite kidney outcome across estimated glomerular filtration rate (eGFR) and urine albumin-to-creatinine ratio (UACR) levels, and to determine whether efpeglenatide's effect varies with these indices.

MATERIALS AND METHODS

AMPLITUDE-O trial data were used to estimate the relationship of eGFR, UACR, and Kidney Disease Improving Global Outcomes (KDIGO) category to the hazard of MACE and the kidney composite. Interactions on these outcomes between eGFR and the UACR, and between each of these variables and efpeglenatide were also assessed.

RESULTS

Baseline eGFR and UACR were available for 3983 participants (mean age 64.5 years). During a median follow-up of 1.8 years, the hazards of MACE and the kidney composite for the lowest versus highest eGFR third were 1.6 (95% confidence interval [CI] 1.2, 2.2) and 2.3 (95% CI 1.9, 2.8), respectively. The hazards for the highest versus the lowest UACR third were 2.3 (95% CI 1.8, 3.1) and 18.0 (95% CI 12.7, 25.5), respectively, and for the high- versus low-risk KDIGO categories the hazards were 2.4 (95% CI 1.8, 3.1) and 16.0 (95% CI 11.6, 22.0), respectively. eGFR and UACR were independent determinants of both outcomes, but negatively interacted with each other for the kidney outcome. Efpeglenatide's effect on both outcomes did not vary with any kidney disease measure (all interaction p values ≥0.26).

CONCLUSIONS

In high-risk people with diabetes, eGFR, UACR, and KDIGO category have different relationships to incident cardiovascular and kidney outcomes. The beneficial effect of efpeglenatide on these outcomes is independent of kidney-related risk category.

2024 Heart Disease and Stroke Statistics: A Report of US and Global Data From the American Heart Association

BACKGROUND

The American Heart Association (AHA), in conjunction with the National Institutes of Health, annually reports the most up-to-date statistics related to heart disease, stroke, and cardiovascular risk factors, including core health behaviors (smoking, physical activity, nutrition, sleep, and obesity) and health factors (cholesterol, blood pressure, glucose control, and metabolic syndrome) that contribute to cardiovascular health. The AHA Heart Disease and Stroke Statistical Update presents the latest data on a range of major clinical heart and circulatory disease conditions (including stroke, brain health, complications of pregnancy, kidney disease, congenital heart disease, rhythm disorders, sudden cardiac arrest, subclinical atherosclerosis, coronary heart disease, cardiomyopathy, heart failure, valvular disease, venous thromboembolism, and peripheral artery disease) and the associated outcomes (including quality of care, procedures, and economic costs).

METHODS

The AHA, through its Epidemiology and Prevention Statistics Committee, continuously monitors and evaluates sources of data on heart disease and stroke in the United States and globally to provide the most current information available in the annual Statistical Update with review of published literature through the year before writing. The 2024 AHA Statistical Update is the product of a full year's worth of effort in 2023 by dedicated volunteer clinicians and scientists, committed government professionals, and AHA staff members. The AHA strives to further understand and help heal health problems inflicted by structural racism, a public health crisis that can significantly damage physical and mental health and perpetuate disparities in access to health care, education, income, housing, and several other factors vital to healthy lives. This year's edition includes additional global data, as well as data on the monitoring and benefits of cardiovascular health in the population, with an enhanced focus on health equity across several key domains.

RESULTS

Each of the chapters in the Statistical Update focuses on a different topic related to heart disease and stroke statistics.

CONCLUSIONS

The Statistical Update represents a critical resource for the lay public, policymakers, media professionals, clinicians, health care administrators, researchers, health advocates, and others seeking the best available data on these factors and conditions.

Adolescent Body Mass Index and Early Chronic Kidney Disease in Young Adulthood

Importance

Despite increasing obesity rates in adolescents, data regarding early kidney sequelae are lacking.

Objective

To assess the association between adolescent body mass index (BMI) and early chronic kidney disease (CKD) in young adulthood (<45 years of age).

Design, Setting, and Participants

This cohort study linked screening data of mandatory medical assessments of Israeli adolescents to data from a CKD registry of a national health care system. Adolescents who were aged 16 to 20 years; born since January 1, 1975; medically evaluated for mandatory military service through December 31, 2019; and insured by Maccabi Healthcare Services were assessed. Individuals with kidney pathology, albuminuria, hypertension, dysglycemia, or missing blood pressure or BMI data were excluded. Body mass index was calculated as weight in kilograms divided by height in meters squared and categorized by age- and sex-matched percentiles according to the US Centers for Disease Control and Prevention. Follow-up started at the time of medical evaluation or January 1, 2000 (whichever came last), and ended at early CKD onset, death, the last day insured, or August 23, 2020 (whichever came first). Data analysis was performed from December 19, 2021, to September 11, 2023.

Main Outcomes and Measures

Early CKD, defined as stage 1 to 2 CKD by moderately or severely increased albuminuria, with an estimated glomerular filtration rate of 60 mL/min/1.73 m2 or higher.

Results

Of 629 168 adolescents evaluated, 593 660 (mean [SD] age at study entry, 17.2 [0.5] years; 323 293 [54.5%] male, 270 367 [45.5%] female) were included in the analysis. During a mean (SD) follow-up of 13.4 (5.5) years for males and 13.4 (5.6) years for females, 1963 adolescents (0.3%) developed early CKD. Among males, the adjusted hazard ratios were 1.8 (95% CI, 1.5-2.2) for adolescents with high-normal BMI, 4.0 (95% CI, 3.3-5.0) for those with overweight, 6.7 (95% CI, 5.4-8.4) for those with mild obesity, and 9.4 (95% CI, 6.6-13.5) for those with severe obesity. Among females, the hazard ratios were 1.4 (95% CI, 1.2-1.6) for those with high-normal BMI, 2.3 (95% CI, 1.9-2.8) for those with overweight, 2.7 (95% CI, 2.1-3.6) for those with mild obesity, and 4.3 (95% CI, 2.8-6.5) for those with severe obesity. The results were similar when the cohort was limited to individuals who were seemingly healthy as adolescents, individuals surveyed up to 30 years of age, or those free of diabetes and hypertension at the end of the follow-up.

Conclusions and Relevance

In this cohort study, high BMI in late adolescence was associated with early CKD in young adulthood. The risk was also present in seemingly healthy individuals with high-normal BMI and before 30 years of age, and a greater risk was seen among those with severe obesity. These findings underscore the importance of mitigating adolescent obesity rates and managing risk factors for kidney disease in adolescents with high BMI.

Association between the Suita Score and Body Composition in Japanese Adults: A Large Cross-Sectional Study

The purpose of this study was to clarify the relationship between the Suita score (a prediction model for the development of cardiovascular disease) and body composition in Japanese health check-up subjects (6873 men and 8685 women). The Suita score includes 8 items (age, gender, smoking, diabetes, blood pressure, low-density lipoprotein, high-density lipoprotein, and chronic kidney disease). Factors associated with the Suita score within body composition-related parameters (body mass index (BMI), waist circumference (WC), fat mass index, fat-free mass index, fat mass to fat-free mass ratio (F-FF ratio), and water mass index) as assessed by bioelectrical impedance analysis were examined. The mean age of subjects was 54.8 years in men and 52.8 years in women (p < 0.0001). The mean BMI was 23.9 kg/m2 in men and 21.8 kg/m2 in women (p < 0.0001). Diabetes mellitus was found in 1282 subjects (18.7%) among men and 816 subjects (9.4%) among women (p < 0.0001). The mean Suita score was 42.0 in men and 29.6 in women (p < 0.0001). In multivariate analysis, WC (p < 0.0001), F-FF ratio (p < 0.0001), and water mass index (p < 0.0001) were independent factors linked to the Suita score for both genders. In conclusion, body composition can be associated with the Suita score in Japanese adults receiving health check-ups.

Association of Chronic Kidney Disease with Cardiovascular Disease in Cancer Patients: A Cross-Sectional Study

INTRODUCTION

Due to the cardiotoxicity of cancer treatment and traditional risk factors for cardiovascular disease (CVD) such as obesity, diabetes, dyslipidemia, and hypertension, cancer patients are at higher risk of developing CVD. However, limited research exists on the correlation between chronic kidney disease (CKD) and CVD risk in cancer patients.

METHODS

This cross-sectional study selected cancer patients aged ≥20 years from the National Health and Nutrition Examination Survey (NHANES) conducted from 2015 to 2020. Multivariable logistic regression was used to assess the association between CKD and CVD in cancer patients. Additionally, subgroup analyses were conducted to investigate the association among different groups of cancer patients.

RESULTS

We included 1,700 adult cancer patients (52.53% were females). After multivariable adjustment for covariates including traditional CVD factors, CKD was significantly associated with CVD, with an odds ratio (95% confidence interval) and p value of 1.61 (1.18, 2.19) and 0.004. Subgroup analyses after multivariable adjustment showed a significant correlation between CKD and increased CVD risk in the following cancer patients: age ≥60 years, males, white ethnicity, and individuals with or without traditional CVD factors (obesity, diabetes, dyslipidemia, and hypertension).

CONCLUSIONS

CKD remains a significant factor in the higher risk of CVD among adult cancer patients in the United States, even after adjustment for traditional CVD risk factors. Therefore, to reduce the risk of CVD in cancer patients, it is important to treat CKD as a non-traditional risk factor for CVD and actively manage it.

Violation of the Constant Genetic Effect Assumption Can Result in Biased Estimates for Non-Linear Mendelian Randomization

INTRODUCTION

Non-linear Mendelian randomization is an extension of conventional Mendelian randomization that performs separate instrumental variable analyses in strata of the study population with different average levels of the exposure. The approach estimates a localized average causal effect function, representing the average causal effect of the exposure on the outcome at different levels of the exposure. The commonly used residual method for dividing the population into strata works under the assumption that the effect of the genetic instrument on the exposure is linear and constant in the study population. However, this assumption may not hold in practice.

METHODS

We use the recently developed doubly ranked method to re-analyse various datasets previously analysed using the residual method. In particular, we consider a genetic score for 25-hydroxyvitamin D (25[OH]D) used in a recent non-linear Mendelian randomization analysis to assess the potential effect of vitamin D supplementation on all-cause mortality.

RESULTS

The effect of the genetic score on 25(OH)D concentrations varies strongly, with a five-fold difference in the estimated genetic association with the exposure in the lowest and highest decile groups. Evidence for a protective causal effect of vitamin D supplementation on all-cause mortality in low vitamin D individuals is evident for the residual method but not for the doubly ranked method. We show that the constant genetic effect assumption is more reasonable for some exposures and less reasonable for others. If the doubly ranked method indicates that this assumption is violated, then estimates from both the residual and doubly ranked methods can be biased, although bias was smaller on average in the doubly ranked method.

CONCLUSION

Analysts wanting to perform non-linear Mendelian randomization should compare results from both the residual and doubly ranked methods, as well as consider transforming the exposure for the residual method to reduce heterogeneity in the genetic effect on the exposure.

Epidemiology and Risk Factors for Stroke in Chronic Kidney Disease: A Narrative Review

Patients with chronic kidney disease (CKD) have a higher risk ofboth ischemic and hemorrhagic stroke. This association appears to be partly independent from the higher prevalence of established risk factors for stroke in patients with CKD, including hypertension and atrial fibrillation. In the present review we aim to discuss the impact of CKD on the risk of stroke and stroke-related consequences, and explore the pathophysiology underpinning the increased risk of stroke in patients with CKD. We cover the clinical association between renal dysfunction and cerebrovascular disease including stroke, silent brain infarct, cerebral small vessel disease, microbleeds, and white matter hyperintensity, and discuss the underlying mechanisms.

Estimation of glomerular filtration rate in cardiorenal patients: a step forward

The progressive reduction in estimated glomerular filtration rate (eGFR) resulting in chronic kidney disease (CKD) is associated with increased risk of cardiovascular disease (CVD) (i.e., cardiorenal disease). Cardiorenal disease is associated with poor outcomes, mainly due to increased cardiovascular (CV) complications and CV death. Data from general population-based studies and studies of cohorts with CKD and/or CVD show that compared with creatinine-based eGFR, cystatin C-based eGFR and creatinine plus cystatin C-based eGFR detect higher risks of adverse CV outcomes and add predictive discrimination to current CVD risk scores. On the other hand, growing clinical evidence supports kidney and CV protective effects of sodium-glucose cotransporter-2 (SGLT2) inhibitors in cardiorenal patients. However, recent data suggest that some detrimental effects of SGLT2 inhibitors on skeletal muscle mass may lead to overestimation of creatinine-based eGFR and subsequent misinterpretation of associated CV risk in patients treated with these agents. Within this framework, we suggest the advisability of using cystatin C and/or creatinine plus cystatin C-based eGFR for routine clinical practice in cardiorenal patients to more accurately stratify CV risk and evaluate the kidney and CV protective effects of SGLT2 inhibitors. In this regard, we make a call to action to investigate the protective effects of these pharmacological agents using cystatin C-based eGFR.

Nuts and Cardiovascular Disease Outcomes: A Review of the Evidence and Future Directions

Nuts are nutrient-rich foods that contain many bioactive compounds that are beneficial for cardiovascular health. Higher consumption of nuts has been associated with a reduced risk of several cardiovascular diseases (CVD) in prospective cohort studies, including a 19% and 25% lower risk of CVD incidence and mortality, respectively, and a 24% and 27% lower risk of coronary heart disease incidence and mortality, respectively. An 18% lower risk of stroke mortality, a 15% lower risk of atrial fibrillation, and a 19% lower risk of total mortality have also been observed. The role of nuts in stroke incidence, stroke subtypes, peripheral arterial disease and heart failure has been less consistent. This narrative review summarizes recommendations for nuts by clinical practice guidelines and governmental organizations, epidemiological evidence for nuts and CVD outcomes, nut-containing dietary patterns, potential mechanisms of nuts and CVD risk reduction, and future research directions, such as the use of biomarkers to help better assess nut intake. Although there are still some uncertainties around nuts and CVD prevention which require further research, as summarized in this review, there is a substantial amount of evidence that supports that consuming nuts will have a positive impact on primary and secondary prevention of CVD.