Relationship between sex and cardiovascular mortality in chronic kidney disease: A systematic review and meta-analysis

Sex and the Risk of Atheromatous and Non-Atheromatous Cardiovascular Disease in CKD: Findings From the CKD-REIN Cohort Study

RATIONALE & OBJECTIVE

Sex differences in cardiovascular disease (CVD) are well-established, but whether chronic kidney disease (CKD) modifies these risk differences, and whether they differ between atheromatous (ACVD) and non-atheromatous (N-ACVD) CVD is unknown. Assessing this interaction was the principal goal of this study.

STUDY DESIGN

Prospective cohort study.

SETTING & PARTICIPANTS

Adults enrolled in the CKD-Renal Epidemiology and Information Network (CKD-REIN) cohort from from 2013 to 2020, a nationally representative sample of 40 nephrology clinics in France.

EXPOSURE

Sex.

OUTCOMES

Fatal and non-fatal composite ACVD events (ischaemic coronary, cerebral, and peripheral artery disease) and composite N-ACVD events (heart failure, haemorrhagic stroke, and arrhythmias).

ANALYTICAL APPROACH

Multivariable cause-specific Cox proportional hazards models.

RESULTS

1,044 women and 1,976 men with moderate to severe CKD (median age, 67 vs. 69; mean estimated glomerular filtration rate [eGFR], 32±12 vs. 33±12 mL/min/1.73m2) were studied. Over a median follow-up of 5.0 (interquartile range, 4.8;5.2) years, the ACVD rate (per 100 patient-years) was significantly lower in women than men: 2.1 (95% confidence interval: 1.6-2.5) vs 3.6 (3.2-4.0) (P<0.01), while the N-ACVD rate was not: 5.7 (5.0-6.5) vs 6.4 (5.8-7.0) (P=0.55). N-ACVD had a steeper relationship with eGFR than did ACVD. There was an interaction (P<0.01) between sex and baseline eGFR and the ACVD hazard: the adjusted hazard ratio for women compared to men was 0.42 (0.25;0.71) at 45 mL/min/1.73m2 and gradually attenuated at lower levels of eGFR, reaching 1.00 (0.62;1.63) at 16 mL/min/1.73m2. In contrast, the N-ACVD hazard did not differ between the sexes across the eGFR range studied.

LIMITATIONS

Cardiovascular biomarkers and sex hormones were not assessed.

CONCLUSION

This study shows how the lower risk of ACVD among women compared to men attenuates fully with kidney disease progression. The equal risk of N-ACVD between sexes across CKD stages and its steeper association with eGFR suggest an important contribution of CKD to the development of this CVD type.

Sex differences in sympathetic activity and pulse wave velocity in adults with chronic kidney disease

Chronic kidney disease (CKD) is characterized by sympathetic nervous system (SNS) overactivity that contributes to increased vascular stiffness and cardiovascular risk. Although it is well established that SNS activity and vascular stiffness are substantially elevated in CKD, whether sex differences in autonomic and vascular function exist in CKD remains unknown. We tested the hypothesis that compared with females, males with CKD have higher baseline sympathetic activity that is related to increased arterial stiffness. One hundred twenty-nine participants (96 males and 33 females) with CKD stages III and IV were recruited and enrolled. During two separate study visits, vascular stiffness was assessed by measuring carotid-to-femoral pulse wave velocity (cfPWV), and resting muscle sympathetic nerve activity (MSNA) was measured by microneurography. Males with CKD had higher resting MSNA compared with females with CKD (68 ± 16 vs. 55 ± 14 bursts/100 heart beats, P = 0.005), whereas there was no difference in cfPWV between the groups (P = 0.248). Resting MSNA was not associated with cfPWV in both males and females. In conclusion, males with CKD have higher resting sympathetic activity compared with females with CKD. However, there was no difference in vascular stiffness between the sexes. There was no correlation between resting MSNA and cfPWV, suggesting that non-neural mechanisms may play a greater role in the progression of vascular stiffness in CKD, particularly in females.NEW & NOTEWORTHY Males with chronic kidney disease (CKD) have higher resting muscle sympathetic nerve activity (MSNA) compared with females. There was no correlation between MSNA and carotid-to-femoral pulse wave velocity (cfPWV), suggesting that non-neural mechanisms may play a greater role in the progression of vascular stiffness in CKD. Sex differences in SNS activity may play a mechanistic role in observations from epidemiological studies suggesting greater cardiovascular risk in males compared with females with CKD.

Sex disparities in mortality and cardiovascular outcomes in chronic kidney disease

Sex (biologically determined) and gender (socially constructed) modulate manifestations and prognosis of a vast number of diseases, including cardiovascular disease (CVD) and chronic kidney disease (CKD). CVD remains the leading cause of death in CKD patients. Population-based studies indicate that women present a higher prevalence of CKD and experience less CVD than men in all CKD stages, although this is not as clear in patients on dialysis or transplantation. When compared to the general population of the same sex, CKD has a more negative impact on women on kidney replacement therapy. European women on dialysis or recipients of kidney transplants have life expectancy up to 44.8 and 19.8 years lower, respectively, than their counterparts of similar age in the general population. For men, these figures stand at 37.1 and 16.5 years, representing a 21% to 20% difference, respectively. Hormonal, genetic, societal, and cultural influences may contribute to these sex-based disparities. To gain a more comprehensive understanding of these differences and their implications for patient care, well-designed clinical trials that involve a larger representation of women and focus on sex-related variables are urgently needed. This narrative review emphasizes the importance of acknowledging the epidemiology and prognosis of sex disparities in CVD among CKD patients. Such insights can guide research into the underlying pathophysiological mechanisms, leading to optimized treatment strategies and ultimately, improved clinical outcomes.

Differences in the epidemiology, management and outcomes of kidney disease in men and women

Improved understanding of differences in kidney disease epidemiology, management and outcomes in men and women could help nephrologists to better meet the needs of their patients from a sex- and gender-specific perspective. Evidence of sex differences in the risk and outcomes of acute kidney injury is mixed and dependent on aetiology. Women have a higher prevalence of chronic kidney disease (CKD) stages 3-5 than men, whereas men have a higher prevalence of albuminuria and hence CKD stages 1-2. Men show a faster decline in kidney function, progress more frequently to kidney failure and have higher mortality and risk of cardiovascular disease than women. However, the protective effect of female sex is reduced with CKD progression. Women are less likely than men to be aware of, screened for and diagnosed with CKD, started on antiproteinuric medication and referred to nephrologist care. They also consistently report a poorer health-related quality of life and a higher symptom burden than men. Women experience greater barriers than men to access the waiting list for kidney transplantation, particularly with respect to older age and obesity. However, women also have longer survival than men after transplantation, which may partly explain the comparable prevalence of transplantation between the sexes.

Sex Differences in Cardiovascular and All-Cause Mortality in Adults with and without CKD: NHANES 1999-2018

Women with CKD had a lower cardiovascular disease mortality risk than men. Kidney function markers (i.e. , eGFR and urinary albumin-to-creatinine ratio) may influence mortality risk in women with CKD, but not in men.

Gaps in Modern Heart Failure and Chronic Kidney Disease Research

Heart failure and chronic kidney disease are common conditions and often coexist. Modern clinical trials are not entirely representative of heart failure patients in the community with respect to age and sex. Despite this, another group of heart failure patients, those with advanced chronic kidney disease, are even less represented in modern clinical trials. This review summarises the evidence for heart failure therapies across age, sex and severity of chronic kidney disease, and outlines the need for further research in these populations.

Sex Disparity in Cause-Specific and All-Cause Mortality Among Incident Dialysis Patients

RATIONALE & OBJECTIVE

Early mortality rates of female patients receiving dialysis have been, at times, observed to be higher than rates among male patients. The differences in cause-specific mortality between male and female incident dialysis patients with kidney failure are not well understood and were the focus of this study.

STUDY DESIGN

Retrospective cohort study.

SETTING & PARTICIPANTS

Incident patients who had initiated dialysis in Australia and New Zealand in 1998-2018.

EXPOSURE

Sex.

OUTCOMES

Cause-specific and all-cause mortality while receiving dialysis, censored for kidney transplant.

ANALYTICAL APPROACH

Adjusted cause-specific proportional hazards models, focusing on the first 5 years following initiation of dialysis.

RESULTS

Among 53,414 patients (20,876 [39%] female) followed for a median period of 2.8 (IQR, 1.3-5.2) years, 27,137 (51%) died, with the predominant cause of death attributed to cardiovascular disease (18%), followed by dialysis withdrawal (16%). Compared with male patients, female patients were more likely to die in the first 5 years after dialysis initiation (adjusted hazard ratio [AHR], 1.08 [95% CI, 1.05-1.11]). Even though female patients experienced a lower risk of cardiovascular disease-related mortality (AHR, 0.93 [95% CI, 0.89-0.98]) than male patients, they experienced a greater risk of infection-related (AHR, 1.20 [95% CI, 1.10-1.32]) and dialysis withdrawal-related (AHR, 1.19 [95% CI, 1.13-1.26]) mortality.

LIMITATIONS

Possibility of residual and unmeasured confounders.

CONCLUSIONS

Compared with male patients, female patients had a higher risk of all-cause mortality in the first 5 years after dialysis initiation, a difference driven by higher rates of mortality from infections and dialysis withdrawals. These findings may inform the study of sex differences in mortality in other geographic settings.

Chronic Kidney Disease Induces Proarrhythmic Remodeling

BACKGROUND

Patients with chronic kidney disease (CKD) are at increased risk of developing cardiac arrhythmogenesis and sudden cardiac death; however, the basis for this association is incompletely known.

METHODS

Here, using murine models of CKD, we examined interactions between kidney disease progression and structural, electrophysiological, and molecular cardiac remodeling.

RESULTS

C57BL/6 mice with adenine supplemented in their diet developed progressive CKD. Electrocardiographically, CKD mice developed significant QT prolongation and episodes of bradycardia. Optical mapping of isolated-perfused hearts using voltage-sensitive dyes revealed significant prolongation of action potential duration with no change in epicardial conduction velocity. Patch-clamp studies of isolated ventricular cardiomyocytes revealed changes in sodium and potassium currents consistent with action potential duration prolongation. Global transcriptional profiling identified dysregulated expression of cellular stress response proteins RBM3 (RNA-binding motif protein 3) and CIRP (cold-inducible RNA-binding protein) that may underlay the ion channel remodeling. Unexpectedly, we found that female sex is a protective factor in the progression of CKD and its cardiac sequelae.

CONCLUSIONS

Our data provide novel insights into the association between CKD and pathologic proarrhythmic cardiac remodeling. Cardiac cellular stress response pathways represent potential targets for pharmacologic intervention for CKD-induced heart rhythm disorders.

CKD-Associated Cardiovascular Mortality in the United States: Temporal Trends From 1999 to 2020

Rationale & Objective

Chronic kidney disease (CKD) is associated with an increased risk of cardiovascular (CV) mortality, but there are limited data on temporal trends disaggregated by sex, race, and urban/rural status in this population.

Study Design

Retrospective observational study.

Setting & Participants

The Centers for Disease Control and Prevention Wide-Ranging, Online Data for Epidemiologic Research database.

Exposure & Predictors

Patients with CKD and end-stage kidney disease (ESKD) stratified according to key demographic groups.

Outcomes

Etiologies of CKD- and ESKD-associated mortality between 1999 and 2000.

Analytical Approach

Presentation of age-adjusted mortality rates (per 100,000 people) characterized by CV categories, ethnicity, sex (male or female), age categories, state, and urban/rural status.

Results

Between 1999 and 2020, we identified 1,938,505 death certificates with CKD (and ESKD) as an associated cause of mortality. Of all CKD-associated mortality, the most common etiology was CV, with 31.2% of cases. Between 1999 and 2020, CKD-related age-adjusted mortality increased by 50.2%, which was attributed to an 86.6% increase in non-CV mortality but a 7.1% decrease in CV mortality. Black patients had a higher rate of CV mortality throughout the study period, although Black patients experienced a 38.6% reduction in mortality whereas White patients saw a 2.7% increase. Hispanic patients experienced a greater reduction in CV mortality over the study period (40% reduction) compared to non-Hispanic patients (3.6% reduction). CV mortality was higher in urban areas in 1999 but in rural areas in 2020.

Limitations

Reliance on accurate characterization of causes of mortality in a large dataset.

Conclusions

Among patients with CKD-related mortality in the United States between 1999 and 2020, there was an increase in all-cause mortality though a small decrease in CV-related mortality. Overall, temporal decreases in CV mortality were more prominent in Hispanic versus non-Hispanic patients and Black patients versus White patients.

Sex differences in microvascular function and arterial hemodynamics in nondialysis chronic kidney disease

Cardiovascular disease (CVD) is the leading cause of death in chronic kidney disease (CKD). Abnormal arterial hemodynamics contribute to CVD, a relationship that can be mediated by microvascular dysfunction. The purpose of this study was to investigate potential sex differences in arterial hemodynamics and microvascular dysfunction in patients with stages 3 to 4 CKD. Vascular function was assessed in 22 male (mean ± SD; age, 56 ± 13 yr) and 10 female (age, 63 ± 9 yr) patients. Arterial hemodynamics were acquired with combined tonometry and oscillometry. Skin blood flow was used as a model of microvascular function. Participants were instrumented with three microdialysis fibers for the delivery of 1) Ringer's solution; 2) superoxide dismutase mimetic, Tempol; and 3) nicotinamide adenine dinucleotide phosphate (NADPH) oxidase inhibitor, apocynin. Blood flow was measured via laser-Doppler flowmetry during standardized local heating (42°C). Central pulse pressure (mean ± SE; 62 ± 9 vs. 46 ± 3 mmHg; P = 0.01) and augmentation index (36 ± 3 vs. 26 ± 3%; P = 0.03) were higher in females. There was a trend for higher central systolic pressures in females (146 ± 9 vs. 131 ± 3 mmHg; P = 0.06). Females reported higher forward (39 ± 4 vs. 29 ± 2 mmHg; P = 0.004) and reflected (27 ± 3 vs. 19 ± 1 mmHg; P < 0.001) wave amplitudes. Cutaneous vascular function was impaired in females compared with males (77 ± 3 vs. 89 ± 1%, P = 0.001). Microvascular function was improved following the delivery of Tempol and apocynin in females but not in males. Female patients with CKD had poorer central hemodynamics and reduced microvascular function compared with their male counterparts. Oxidative stress may contribute to lower microvascular function observed in females.NEW & NOTEWORTHY There are limited data regarding the physiological mechanisms of potential sex differences in central hemodynamics and vascular function in chronic kidney disease (CKD). We report that older female patients with nondialysis CKD have higher central pulse pressures compared with male patients with CKD. In addition, older females with CKD have lower microvascular function compared with their male counterparts, and oxidative stress contributes to the lower microvascular function in older female patients with CKD.

Hypertension in chronic kidney disease: What lies behind the scene

Hypertension is a frequent condition encountered during kidney disease development and a leading cause in its progression. Hallmark factors contributing to hypertension constitute a complexity of events that progress chronic kidney disease (CKD) into end-stage renal disease (ESRD). Multiple crosstalk mechanisms are involved in sustaining the inevitable high blood pressure (BP) state in CKD, and these play an important role in the pathogenesis of increased cardiovascular (CV) events associated with CKD. The present review discusses relevant contributory mechanisms underpinning the promotion of hypertension and their consequent eventuation to renal damage and CV disease. In particular, salt and volume expansion, sympathetic nervous system (SNS) hyperactivity, upregulated renin–angiotensin–aldosterone system (RAAS), oxidative stress, vascular remodeling, endothelial dysfunction, and a range of mediators and signaling molecules which are thought to play a role in this concert of events are emphasized. As the control of high BP via therapeutic interventions can represent the key strategy to not only reduce BP but also the CV burden in kidney disease, evidence for major strategic pathways that can alleviate the progression of hypertensive kidney disease are highlighted. This review provides a particular focus on the impact of RAAS antagonists, renal nerve denervation, baroreflex stimulation, and other modalities affecting BP in the context of CKD, to provide interesting perspectives on the management of hypertensive nephropathy and associated CV comorbidities.

Sex Differences in CKD-Associated Mortality From 1990 to 2019: Data From the Global Burden of Disease Study

Rationale & Objective

Previous studies have shown chronic kidney disease (CKD) mortality rates to be lower among females than males. We aimed to examine the extent to which sex differences vary over time, among countries, and with age, using Global Burden of Disease (GBD) Study data.

Study Design

Observational epidemiological study.

Setting & Participants

GBD Study, which used published literature, vital registration systems, kidney replacement therapy registries, and household surveys.

Exposures

Sex.

Outcomes

CKD-associated mortality rate (per 100,000 population).

Analytical Approach

Changes in CKD mortality between 1990 and 2019 were compared between sexes, globally, and separately for the 50 most populous countries. For 2019 only, sex differences in age-standardized and age-specific mortality were compared between countries.

Results

There was no change in global age-standardized mortality for either sex between 1990 and 2019, with female mortality consistently 30% lower than male mortality. Percentage changes were less favorable among females than males in two-thirds of the 50 countries examined, with the greatest change disparities observed in Egypt, Thailand, and Malaysia. Although Mexico exhibited the greatest overall percentage increase, the increase was smaller in females (81% vs 138%). In 2019, female mortality varied between 47% lower and 60% higher than male mortality (in Angola and Egypt, respectively). In most countries, female mortality was lower across all age groups, with no narrowing of sex differences with age.

Limitations

We were not able to assess the sex differences according to CKD stage and we did not explore other disease metrics (eg, disability-adjusted life years).

Conclusions

Percentage changes in age-standardized CKD mortality have tended to be less favorable among females than males, with notable exceptions. Similarly, although female mortality is generally lower than male mortality, there are multiple examples of the opposite. Country-specific assessments of sex differences in CKD-associated outcomes are essential for equitable care.

Multiple pathways and mediation effects of built environment on kidney disease rate via mitigation of atmospheric threats

Air pollution and high temperatures can increase kidney disease rate, especially under climate change. A well-designed urban environment has mediating effects on atmospheric environmental threats and promoting human health, but previous studies have overlooked these effects. This study used partial least squares modeling and urban-scale data from Taiwan to identify the crucial effects (i.e., direct, indirect, and total effects) and pathways of urban form (i.e., urban development intensity, land-use mix, and urban sprawl), urban greening (i.e., green coverage), urban industrial status (e.g., industrial level), atmospheric environment (i.e., high temperature and air pollution), and socioeconomic status (i.e., elderly ratio, medical resources, and economic status) on kidney disease rate. Maximizing land-use mix and green coverage and minimizing urban development intensity, urban sprawl, and industrial levels could help reduce kidney disease rate. Air pollution and high temperature had a mediation effect of built environment on kidney disease rate; with the mediation effect of air pollution was greater than that of high temperature. Furthermore, air pollution, high temperature, and elderly ratio increased kidney disease rate, whereas medical resources decreased kidney disease rate. This study is the first to consider the impact (i.e., direct, indirect, and total effects) and pathways of built environment characteristics on kidney disease rate. The findings revealed that an appropriate urban policy might be a practical strategy and lower kidney disease rate for a healthy city development. Moreover, this study provides a new approach for clarifying complex relationships and identifying crucial factors.

A systematic review and meta-analysis of the association between uric acid levels and chronic kidney disease

The function of uric acid (UA) in the genesis and evolution of chronic kidney disease (CKD) has motivated numerous studies, but the results remain inconclusive. We sought to conduct a systematic review and meta-analysis of cohort studies aiming to analyze the association of UA levels with the incidence and progression of CKD. Pubmed/Medline, Lilacs/Bireme and Web of Science were searched to identify eligible studies, following the PRISMA protocol. Data were presented for CKD incidence and progression separately. For the meta-analysis, studies with data stratified by subgroups according to serum UA levels were selected. The inverse variance-weighted random effects model was used to generate a combined effect estimate. Meta-regressions were performed to identify the causes of heterogeneity. The Newcastle-Ottawa Scale was used to assess the risk of bias. The publication bias was tested by funnel plot and Egger's test. Eighteen CKD incidence studies (n = 398,663) and six CKD progression studies (n = 13,575) were included. An inverse relationship was observed between UA levels and protection from CKD incidence and progression. Lower UA levels were protective for the risk of CKD incidence (RR 0.65 [95% CI 0.56-0.75]) and progression (RR 0.55 [95% CI 0.44-0.68]). UA seems to be implicated both in the genesis of CKD and its evolution.

Does Chronic Kidney Disease Really Affect the Complications and Prognosis After Liver Resection for Hepatocellular Carcinoma? A Meta-Analysis

Purpose

The purpose of this meta-analysis was to analyze whether chronic kidney disease (CKD) affected the complications and prognosis after liver resection for hepatocellular carcinoma.

Methods

The PubMed, Embase, and Cochrane Library databases were searched from inception to 22 February 2022 to find eligible studies. Complications, overall survival (OS), and disease-free survival (DFS) were collected, and this meta-analysis was performed with RevMan 5.3.

Results

A total of nine studies including 6,541 patients were included in this meta-analysis. After pooling all baseline information, the CKD group had a higher rate of Child-Pugh grade B than the Non-CKD group (OR = 1.58, 95% CI = 1.3 to 1.93, P < 0.00001). As for surgery-related information, the CKD group had larger blood loss (MD = −404.79, 95% CI = −509.70 to −299.88, P < 0.00001), and higher rate of blood transfusion (OR = 2.47, 95% CI = 1.85 to 3.3, P < 0.00001). In terms of complications, the CKD group had a higher rate of overall complications (OR = 2.1, 95% CI = 1.57 to 2.81, P < 0.00001) and a higher rate of ≥ grade III complications (OR = 2.04, 95% CI = 1.57 to 2.81, P = 0.0002). The CKD group had poor OS compared with the non-CKD group (HR = 1.28, 95% CI = 1.1 to 1.49, P = 0.001). However, in terms of DFS, no significant difference was found (HR = 1.11, 95% CI = 0.96 to 1.28, P = 0.16).

Conclusion

Preexisting CKD was associated with higher ratio of complications and poor OS.

Sex, Gender, and Cardiovascular Disease in Chronic Kidney Disease

This review on sex, gender, and cardiovascular diseases in chronic kidney disease attempts to summarize what we know and what we do not know about the effects of sex and gender on cardiovascular disease in chronic kidney disease. We discuss and define the terminology of sex and gender, and the underlying physiology for differences observed. We explore how sex and gender affect specific cardiovascular diseases such as coronary artery disease, congestive heart failure, arrhythmias, cardiovascular mortality, and pre-eclampsia. We conclude with a review of recent randomized controlled trials and highlight the pharmacokinetic and pharmacodynamic differences in both sexes.