Impact of Kidney Function on Cardiovascular Risk and Mortality: A Comparison of South Asian and European Cohorts

Prospective Study on Kidney Dysfunction Markers and Risk for Mortality among South Asians

Introduction

Associations between markers of impaired kidney function and adverse outcomes among South Asians is understudied and could differ from existing data derived mostly from North American or European cohorts.

Methods

We conducted a prospective analysis of 9797 participants from the ongoing cardiometabolic risk reduction study in South Asia, India. We examined the associations between baseline spot urine albumin-to-creatinine (UACR) ratio and creatinine-based estimated glomerular filtration rate (eGFR) estimating equations with all-cause mortality using Cox proportional hazards regression, adjusting for baseline age, sex, diabetes, systolic blood pressure, tobacco, history of cardiovascular disease, and cholesterol. Additionally, we calculated population attributable fraction (PAF) for both markers.

Results

Over a median 7-year follow-up, with 66,909 person-years, 791 deaths occurred. At baseline, the weighted prevalence of UACR ≥ 30 mg/g and eGFRCKD-EPI 2009 <60 ml/min per 1.73 m2 was 6.6% and 1.6%, respectively. The risk for mortality was increased with higher UACR (10-30 hazard ratio [HR]: 1.6 [1.2-2.1]), 30-300 HR: 2.4 [1.8-3.1]), and ≥300 (HR: 6.0 [3.8-9.4] relative to UACR <10 mg/g). Risk for mortality was also higher with lower eGFRCKD-EPI 2009 (44-30; HR: 4.5 [2.5-8.3] and <30 HR: 7.0 [3.7-13.0], relative to 90-104 ml/min per 1.73 m2). PAF for mortality because of UACR ≥30 mg/g and eGFRCKD-EPI 2009 <45 ml/min per 1.73 m2 were 24.4% and 13.4%, respectively.

Conclusion

Single-time point assessment of UACR ≥30 mg/g or eGFRCKD-EPI 2009 <45 ml/min per 1.73 m2 portends higher mortality risk among urban South Asians. Because albuminuria is common and associated with accelerated decline in GFR, screening and targeted efforts to reduce albuminuria are warranted.

Kidney function decline is associated with mortality events: over a decade of follow-up from Tehran Lipid and Glucose Study

BACKGROUND

To investigate the association between estimated glomerular filtration rate (eGFR) change and mortality risk in a cohort from the Middle East and North Africa region with increasing chronic kidney disease burden.

METHODS

We included 2210 participants aged ≥ 50 years from the prospective cohort of the Tehran Lipid and Glucose Study. The interval for eGFR measurement was between the examinations in 2002-2005 to 2009-2011, and participants were followed through March 2018. Glomerular filtration rate was estimated from serum creatinine using the CKD-EPI creatinine equation. We assessed the association of rapid kidney function decline, (defined as annual eGFR decline ≥ 3 ml/min/1.73 m2 per year); ≥ 30% eGFR decline over six years; and certain drop in kidney function (≥ 25% eGFR decline plus drop in eGFR category) with mortality outcomes.

RESULTS

During a median follow-up of 14.3 years after recruitment, 315 all-cause and 112 cardiovascular disease deaths were recorded. The multivariable-adjusted hazard ratios (HRs) and 95% confidence intervals (CIs) of all-cause death for rapid kidney function decline, ≥ 30% decline in eGFR over 6 years, and drop in kidney function were 1.68 (1.24-2.27), 2.01 (1.46-2.78), and 1.49 (1.11-1.98), respectively. The HRs of all-cause death and for rapid kidney function decline in those without and with chronic kidney disease were 1.41 (1.03-1.91) and 3.38 (1.69-6.76), respectively. Similar findings were observed regarding cardiovascular disease-related and non-cardiovascular disease-related mortality.

CONCLUSIONS

Estimated GFR decline is associated with an increased mortality risk, indicating its ability to provide additional prognostic information beyond traditional risk predictors in the general population.

Prevalence of Cardiovascular Diseases in South Asians: Scrutinizing Traditional Risk Factors and Newly Recognized Risk Factors Sarcopenia and Osteopenia/Osteoporosis

One of the primary reasons for complications and death worldwide are cardiovascular diseases (CVDs), with a death toll of approximately 18 million per year. CVDs include cardiomyopathy, hypertension, ischemic heart disease, coronary heart disease, myocardial infarction, heart attack, hearth failure, etc. Over 80% of the CVD mortality is recorded from lower and middle-income countries. Records from the past decade have highlighted the increase of CVDs among the South Asian populations, and the prime purpose of the review is to jot down the reasons for the steep spike in CVDs. Studies analyzing the causative factors for the increase of CVDs in South Asians are still to be verified. Apart from known predisposing and lifestyle factors, other emerging risk factors associated with CVDs, namely the musculoskeletal diseases sarcopenia and osteopenia, should be tracked to tackle research gaps in upcoming analyses. This requires loads of scientific efforts. With proper monitoring, the raising alarm that the CVD burden generates can be reduced. This review discusses the already established signs and recognizes important clues to the emerging etiology of CVDs in the Asian population and prevention measures to keep it at bay.

Disentangling Dual Threats: Premature Coronary Artery Disease and Early-Onset Type 2 Diabetes Mellitus in South Asians

South Asian individuals (SAs) face heightened risks of premature coronary artery disease (CAD) and early-onset type 2 diabetes mellitus (T2DM), with grave health, societal, and economic implications due to the region's dense population. Both conditions, influenced by cardiometabolic risk factors such as insulin resistance, hypertension, and central adiposity, manifest earlier and with unique thresholds in SAs. Epidemiological, demographic, nutritional, environmental, sociocultural, and economic transitions in SA have exacerbated the twin epidemic. The coupling of premature CAD and T2DM arises from increased obesity due to limited adipose storage, early-life undernutrition, distinct fat thresholds, reduced muscle mass, and a predisposition for hepatic fat accumulation from certain dietary choices cumulatively precipitating a decline in insulin sensitivity. As T2DM ensues, the β-cell adaptive responses are suboptimal, precipitating a transition from compensatory hyperinsulinemia to β-cell decompensation, underscoring a reduced functional β-cell reserve in SAs. This review delves into the interplay of these mechanisms and highlights a prediabetes endotype tied to elevated vascular risk. Deciphering these mechanistic interconnections promises to refine stratification paradigms, surpassing extant risk-prediction strategies.

Kidney Function and Long-Term Risk of End-Stage Kidney Disease and Mortality in a Multiethnic Population

Introduction

Contemporary differences between South Asian and White ethnicities in the incidence of end-stage kidney disease (ESKD) and mortality are poorly described.

Methods

Data for all South Asian patients who had an estimated glomerular filtration rate (eGFR) measure after January 1, 2006, and 1 million randomly selected participants of other ethnicities were extracted from the Clinical Practice Research Datalink (CPRD). All participants were followed-up with from index date until ESKD, all-cause mortality, or end of study. All-cause mortality rate and ESKD incidence rate by age were described among Whites and South Asians, and adjusted hazard ratios (HRs) of these 2 outcomes by baseline eGFR estimated using Cox proportional hazard model.

Results

A total of 40,888 South Asians and 236,634 Whites were followed for a median of 5.3 and 9.4 years for ESKD incidence and mortality outcomes, respectively. All-cause mortality rates were higher among Whites than South Asians; South Asian women aged between 70 and 85 years had a slightly higher ESKD incidence rate compared to their White counterparts. Compared to Whites with a baseline eGFR of 90 ml/min per 1.73 m2, adjusted HRs for all-cause mortality were significantly lower among South Asians than Whites; however, adjusted HRs for ESKD incidence by baseline eGFR were similar in both ethnicities. Calculating South Asian eGFRs using an ethnicity-specific equation had no impact on the results.

Conclusions

South Asians experience lower mortality than Whites but not substantially higher rates of ESKD. Further research is warranted to better understand the reasons for these ethnic differences and possible impacts on chronic kidney disease (CKD) service delivery and patient outcomes.

One Heartbeat Away from a Prediction Model for Cardiovascular Diseases in Patients with Chronic Kidney Disease: A Systematic Review

INTRODUCTION

Patients with chronic kidney disease (CKD) have a high risk of cardiovascular disease (CVD). Prediction models, combining clinical and laboratory characteristics, are commonly used to estimate an individual's CVD risk. However, these models are not specifically developed for patients with CKD and may therefore be less accurate. In this review, we aim to give an overview of CVD prognostic studies available, and their methodological quality, specifically for patients with CKD.

METHODS

MEDLINE was searched for papers reporting CVD prognostic studies in patients with CKD published between 2012 and 2021. Characteristics regarding patients, study design, outcome measurement, and prediction models were compared between included studies. The risk of bias of studies reporting on prognostic factors or the development/validation of a prediction model was assessed with, respectively, the QUIPS and PROBAST tool.

RESULTS

In total, 134 studies were included, of which 123 studies tested the incremental value of one or more predictors to existing models or common risk factors, while only 11 studies reported on the development or validation of a prediction model. Substantial heterogeneity in cohort and study characteristics, such as sample size, event rate, and definition of outcome measurements, was observed across studies. The most common predictors were age (87%), sex (75%), diabetes (70%), and estimated glomerular filtration rate (69%). Most of the studies on prognostic factors have methodological shortcomings, mostly due to a lack of reporting on clinical and methodological information. Of the 11 studies on prediction models, six developed and internally validated a model and four externally validated existing or developed models. Only one study on prognostic models showed a low risk of bias and high applicability.

CONCLUSION

A large quantity of prognostic studies has been published, yet their usefulness remains unclear due to incomplete presentation, and lack of external validation of prognostic models. Our review can be used to select the most appropriate prognostic model depending on the patient population, outcome, and risk of bias. Future collaborative efforts should aim at improving existing models by externally validating them, evaluating the addition of new predictors, and assessment of the clinical impact.

REGISTRATION

We have registered the protocol of our systematic review on PROSPERO (CRD42021228043).

Differential Associations of Cystatin C Versus Creatinine-Based Kidney Function With Risks of Cardiovascular Event and Mortality Among South Asian Individuals in the UK Biobank

Background South Asian individuals have increased cardiovascular disease and mortality risks. Reliance on creatinine- rather than cystatin C-based estimated glomerular filtration rate (eGFRcys) may underestimate the cardiovascular disease risk associated with chronic kidney disease. Methods and Results Among 7738 South Asian UK BioBank participants without prevalent heart failure (HF) or atherosclerotic cardiovascular disease, we investigated associations of 4 eGFRcys and creatinine-based estimated glomerular filtration rate categories (<45, 45-59, 60-89, and ≥90 mL/min per 1.73 m2) with risks of all-cause mortality, incident HF, and incident atherosclerotic cardiovascular disease. The mean age was 53±8 years; 4085 (53%) were women. Compared with creatinine, cystatin C identified triple the number of participants with estimated glomerular filtration <45 (n=35 versus n=113) and 6 times the number with estimated glomerular filtration 45 to 59 (n=80 versus n=481). After multivariable adjustment, the eGFRcys 45 to 59 category was associated with higher risks of mortality (hazard ratio [HR], 2.38 [95% CI, 1.55-3.65]) and incident HF (sub-HR [sHR], 1.87 [95% CI, 1.09-3.22]) versus the eGFRcys ≥90 category; the creatinine-based estimated glomerular filtration rate 45 to 59 category had no significant associations with outcomes. Of the 7623 participants with creatinine-based estimated glomerular filtration rate ≥60, 498 (6.5%) were reclassified into eGFRcys <60 categories. Participants who were reclassified as having eGFRcys <45 had higher risks of mortality (HR, 4.88 [95% CI, 2.56-9.31]), incident HF (sHR, 4.96 [95% CI, 2.21-11.16]), and incident atherosclerotic cardiovascular disease (sHR, 2.29 [95% CI, 1.14-4.61]) versus those with eGFRcys ≥90; those reclassified as having eGFRcys 45 to 59 had double the mortality risk (HR, 2.25 [95% CI, 1.45-3.51]). Conclusions Among South Asian individuals, cystatin C identified a high-risk chronic kidney disease population that was not detected by creatinine and enhanced estimated glomerular filtration rate-based risk stratification for mortality, incident HF, and incident atherosclerotic cardiovascular disease.

South Asian ethnicity: What can we do to make this risk enhancer a risk equivalent?

South Asians account for around 25% of the global population and are the fastest-growing ethnicity in the US. This population has an increasing burden of atherosclerotic cardiovascular disease (ASCVD) which is also seen in the diaspora. Current risk prediction equations underestimate this risk and consider the South Asian ethnicity as a risk-enhancer among those with borderline-intermediate risk. In this review, we discuss why the South Asian population is at a higher risk of ASCVD and strategies to mitigate this increased risk.

Estimated glomerular filtration rate trajectories in south Asians: Findings from the cardiometabolic risk reduction in south Asia study

Background

Few longitudinal data characterize kidney function decline among South Asians, one of the world's largest population groups. We aimed to identify estimated glomerular filtration rate (eGFR) trajectories in a population-based cohort from India and assess predictors of rapid kidney function decline.

Methods

We used 6-year longitudinal data from participants of a population-representative study from Delhi and Chennai, India who had at least two serum creatinine measures and baseline CKD-EPI eGFR> 60 ml/min/1.73m² (n=7779). We used latent class trajectory modeling to identify patterns of kidney function trajectory (CKD-EPI eGFR) over time. In models accounting for age, sex, education, and city, we tested the association between 15 hypothesized risk factors and rapid kidney function decline.

Findings

Baseline mean eGFR was 108 (SD 16); median eGFR was 110 [IQR: 99-119] ml/min/1.73m². Latent class trajectory modeling and functional characterization identified three distinct patterns of eGFR: class-1 (no decline; 58%) annual eGFR change 0.2 [0.1, 0.3]; class-2 (slow decline; 40%) annual eGFR change -0.2 [-0.4, -0.1], and class-3 (rapid decline; 2%) annual eGFR change -2.7 [-3.4, -2.0] ml/min/1.73m². Albuminuria (>30 mg/g) was associated with rapid eGFR decline (OR for class-3 vs class-1: 5.1 [95% CI: 3.2; 7.9]; class-3 vs. class-2: 4.3 [95% CI:2.7; 6.6]). Other risk factors including self-reported diabetes, cardiovascular disease, peripheral arterial disease, and metabolic biomarkers such as HbA1c and systolic blood pressure were associated with rapid eGFR decline phenotype but potential 'non-traditional' risk factors such as manual labor or household water sources were not.

Interpretation

Although mean and median eGFRs in our population-based cohort were higher than those reported in European cohorts, we found that a sizeable number of adults residing in urban India are experiencing rapid kidney function decline. Early and aggressive risk modification among persons with albuminuria could improve kidney health among South Asians.

Funding

The CARRS study has been funded with federal funds from the National Heart, Lung, and Blood Institute, National Institutes of Health, under Contract No. HHSN2682009900026C and P01HL154996. Dr. Anand was supported by NIDDK K23DK101826 and R01DK127138.

Prevalence and Clinical Impact of Electrocardiographic Abnormalities in Patients with Chronic Kidney Disease

Chronic kidney disease (CKD) is a strong risk factor for cardiovascular disease. An electrocardiogram (ECG) is a basic test for screening cardiovascular disease. However, the impact of ECG abnormalities on cardiovascular prognosis in patients with CKD is largely unknown. A total of 2442 patients with CKD (stages 3−5) who underwent ECG between 2013 and 2015 were selected from the electronic health record database of the Korea University Anam Hospital. ECG abnormalities were defined using the Minnesota classification. The five-year major adverse cerebrocardiovascular event (MACCE), the composite of death, myocardial infarction (MI), and stroke were analyzed. The five-year incidences for MACCE were 27.7%, 20.8%, and 17.2% in patients with no, minor, and major ECG abnormality (p < 0.01). Kaplan−Meier curves also showed the highest incidence of MI, death, and MACCE in patients with major ECG abnormality. Multivariable Cox regression analysis revealed age, sex, diabetes, CKD stage, hsCRP, antipsychotic use, and major ECG abnormality as independent risk predictors for MACCE (adjusted HR of major ECG abnormality: 1.39, 95% CI: 1.09−1.76, p < 01). Among the detailed ECG diagnoses, sinus tachycardia, myocardial ischemia, atrial premature complex, and right axis deviation were proposed as important ECG diagnoses. The accuracy of cardiovascular risk stratification was improved when the ECG results were added to the conventional SCORE model (net reclassification index 0.07). ECG helps to predict future cerebrocardiovascular events in CKD patients. ECG diagnosis can be useful for cardiovascular risk evaluation in CKD patients when applied in addition to the conventional risk stratification model.

Prediction of cardiovascular outcome by estimated glomerular filtration rate among high-risk patients: a Thai nationwide cohort study

BACKGROUND

Decline of estimated glomerular filtration rate (eGFR) is associated with increased cardiovascular (CV) morbidity and mortality, but the predictive value of different eGFR on CV outcomes is limited in Southeast Asian populations.

AIMS

We aimed to stratify CV outcomes according to renal function among Thai patients with high atherosclerosis risk.

METHODS

We performed a secondary analysis in a 5-year national cohort entitled "CORE-Thailand study." Subjects were classified in 6 groups according to baseline kidney function: group I, eGFR ≥ 90; group II, eGFR 60-89; group IIIa, eGFR 45-59; group IIIb, eGFR 30-44; group IV, eGFR 15-29; group V, eGFR < 15 ml/min/1.73 m² or receiving renal replacement therapy. The primary outcome was 4-point major adverse cardiovascular events (MACE). Secondary outcomes included all-cause mortality, CV mortality, hospitalization for heart failure, nonfatal myocardial infarction, and nonfatal stroke.

RESULTS

A total of 6376 subjects (3467 men and 2909 women) were categorized in 6 groups. After adjusting covariates in the Cox proportional hazards model, compared to group I, subjects in groups II-V had a 1.65-fold, 2.17-fold, 2.67-fold, 4.24-fold, and 4.87-fold risk for 4-point MACE, respectively, with statistical significance at P < 0.05 in all groups. Kaplan-Meier analysis illustrated stepwise lower survivals from 4-point MACE following the groups with lower baseline eGFR (log-rank test with P < 0.001). All secondary outcomes showed similar trends as the primary outcome, except nonfatal stroke.

CONCLUSION

Lower baseline kidney function was independently associated with increased risk of CV events and all-cause mortality in Thai populations at high CV risk.

Circulating Cystatin C Is an Independent Risk Marker for Cardiovascular Outcomes, Development of Renal Impairment, and Long-Term Mortality in Patients With Stable Coronary Heart Disease: The LIPID Study

Background

Elevated plasma cystatin C levels reflect reduced renal function and increased cardiovascular risk. Less is known about whether the increased risk persists long‐term or is independent of renal function and other important biomarkers.

Methods and Results

Cystatin C and other biomarkers were measured at baseline (in 7863 patients) and 1 year later (in 6106 patients) in participants in the LIPID (Long‐Term Intervention with Pravastatin in Ischemic Disease) study, who had a previous acute coronary syndrome. Outcomes were ascertained during the study (median follow‐up, 6 years) and long‐term (median follow‐up, 16 years). Glomerular filtration rate (GFR) was estimated using Chronic Kidney Disease Epidemiology Collaboration equations (first GFR‐creatinine, then GFR‐creatinine‐cystatin C). Over 6 years, in fully adjusted multivariable time‐to‐event models, with respect to the primary end point of coronary heart disease mortality or nonfatal myocardial infarction, for comparison of Quartile 4 versus 1 of baseline cystatin C, the hazard ratio was 1.37 (95% CI, 1.07–1.74; P=0.01), and for major cardiovascular events was 1.47 (95% CI, 1.19–1.82; P<0.001). Over 16 years, the association of baseline cystatin C with coronary heart disease, cardiovascular, and all‐cause mortality persisted (each P<0.001) and remained significant after adjustment for estimated GFR‐creatinine‐cystatin C. Cystatin C also predicted the development of chronic kidney disease for 6 years (odds ratio, 6.61; 95% CI, 4.28–10.20) independently of estimated GFR‐creatinine and other risk factors. However, this association was no longer significant after adjustment for estimated GFR‐creatinine‐cystatin C.

Conclusions

Cystatin C independently predicted major cardiovascular events, development of chronic kidney disease, and cardiovascular and all‐cause mortality. Prediction of long‐term mortality was independent of improved estimation of GFR.

Registration

URL: https://anzctr.org.au; Unique identifier: ACTRN12616000535471.

Managing cardiovascular disease risk in South Asian kidney transplant recipients

South Asians (SA) are at higher cardiovascular risk than other ethnic groups, and SA kidney transplant recipients (SA KTR) are no exception. SA KTR experience increased major adverse cardiovascular events both early and late post-transplantation. Cardiovascular risk management should therefore begin well before transplantation. SA candidates may require aggressive screening for pre-transplant cardiovascular disease (CVD) due to their ethnicity and comorbidities. Recording SA ethnicity during the pre-transplant evaluation may enable programs to better assess cardiovascular risk, thus allowing for earlier targeted peri- and post-transplant intervention to improve cardiovascular outcomes. Diabetes remains the most prominent post-transplant cardiovascular risk factor in SA KTR. Diabetes also clusters with other metabolic syndrome components including lower high-density lipoprotein cholesterol, higher triglycerides, hypertension, and central obesity in this population. Dyslipidemia, metabolic syndrome, and obesity are all significant CVD risk factors in SA KTR, and contribute to increased insulin resistance. Novel biomarkers such as adiponectin, apolipoprotein B, and lipoprotein (a) may be especially important to study in SA KTR. Focused interventions to improve health behaviors involving diet and exercise may especially benefit SA KTR. However, there are few interventional clinical trials specific to the SA population, and none are specific to SA KTR. In all cases, understanding the nuances of managing SA KTR as a distinct post-transplant group, while still screening for and managing each CVD risk factor individually in all patients may help improve the long-term success of all kidney transplant programs catering to multi-ethnic populations.

American Indian chronic Renal insufficiency cohort study (AI-CRIC study)

BACKGROUND

Chronic kidney disease (CKD) is an increasing epidemic globally that is associated with adverse health outcomes including end stage kidney disease (ESKD), cardiovascular disease (CVD), and death. American Indians (AIs) have a higher prevalence of CKD than most other racial/ethnic groups, due in part to a high prevalence of type 2 diabetes. Other genetic and environmental factors not yet identified may also contribute to the disproportionate burden of CKD in AIs.

METHOD

We will establish 3 clinical centers to recruit AIs from the Southwest United States (US) to expand the Chronic Renal Insufficiency Cohort (CRIC) study. We will follow the current CRIC protocol for kidney and cardiovascular measures and outcomes, which include ambulatory monitoring of kidney function and the use of mobile health technologies for CVD sub-phenotyping, and compare the outcomes in AIs with those in other racial/ethnic groups in CRIC.

DISCUSSION

AI-CRIC will identify the role of various risk factors for rapid loss of kidney function among AIs of the Southwest US. In addition, to better understand the natural history of CKD and CVD in this high-risk population, we will identify unique risk factors for CKD and CVD progression in AIs. We will also compare event rates and risk factors for kidney and cardiovascular events in AIs with the other populations represented in CRIC.