Women and renal replacement therapy in Europe: lower incidence, equal access to transplantation, longer survival than men

Visceral fat and attribute-based medicine in chronic kidney disease

Visceral adipose tissue plays a central role in obesity and metabolic syndrome and is an independent risk factor for both cardiovascular and metabolic disorders. Increased visceral adipose tissue promotes adipokine dysregulation and insulin resistance, leading to several health issues, including systemic inflammation, oxidative stress, and activation of the renin-angiotensin-aldosterone system. Moreover, an increase in adipose tissue directly and indirectly affects the kidneys by increasing renal sodium reabsorption, causing glomerular hyperfiltration and hypertrophy, which leads to increased proteinuria and kidney fibrosis/dysfunction. Although the interest in the adverse effects of obesity on renal diseases has grown exponentially in recent years, the relationship between obesity and renal prognosis remains controversial. This may be attributed to the long clinical course of obesity, numerous obesity-related metabolic complications, and patients' attributes. Multiple individual attributes influencing the pathophysiology of fat accumulation make it difficult to understand obesity. In such cases, it may be effective to elucidate the pathophysiology by conducting research tailored to individual attributes from the perspective of attribute-based medicine/personalized medicine. We consider the appropriate use of clinical indicators necessary, according to attributes such as chronic kidney disease stage, level of visceral adipose tissue accumulation, age, and sex. Selecting treatments and clinical indicators based on individual attributes will allow for advancements in the clinical management of patients with obesity and chronic kidney disease. In the clinical setting of obesity-related nephropathy, it is first necessary to accumulate attribute-based studies resulting from the accurate evaluation of visceral fat accumulation to establish evidence for promoting personalized medicine.

Comorbidity, life-style factors and healthcare utilization in incident chronic kidney disease: sex-specific analyses of claims data

BACKGROUND

Chronic kidney disease (CKD) is common in aging men and women. In contrast to other European countries, Germany lacks CKD registries. The aim of this study was to determine the incidence of CKD stages 2-5 in men and women in Germany. Furthermore, differences between the sexes in terms of comorbidities, potentially inappropriate medications (PIM), and healthcare utilization were examined.

METHODS

In this retrospective observational study, claims data from members of a statutory health insurance fund aged 18 years or older with incident CKD between 2011 and 2018 were analyzed. Incident CKD was defined as having two confirmed diagnoses of CKD stages 2-5 from outpatient care or one primary or secondary diagnosis from inpatient care.

RESULTS

The age- and sex-standardized incidence of all CKD stages was 945/100 000 persons between 2011 and 2018. Incident CKD, especially stages 3 and 4, occurred more frequently in women, while the incidence of stages 2 and 5 was higher in men. While women visited their GP more frequently and were prescribed PIMs more often, men were more likely to visit a nephrologist and were more often hospitalized after the incident CKD diagnosis.

CONCLUSION

More awareness needs to be raised towards the early detection of CKD and the use of PIMs, especially in women. Improved care coordination is needed to avoid an overprovision of patients with uncomplicated incident stages and ensure that patients with advanced CKD stages get timely access to specialist care.

Gender-specific differences in hemodialysis patients: a multicenter longitudinal study from Serbia

PURPOSE

The study was undertaken with the aim to determine gender-specific differences in incident hemodialysis (HD) patient and their changes over time.

METHODS

The retrospective longitudinal closed cohort study involved 441 incident patients starting HD in 2014 and followed for 1-59 (median 43, IQR 40) months. Demographic, clinical data, treatment characteristics, laboratory findings and outcome were abstracted from the patients' medical records.

RESULTS

The relative number of males on HD was about twice that of females throughout the five years investigated. At the beginning of the study, no significant differences were found in the main demographic and clinical characteristics except that diabetes was more often the underlying disease in men than in women. Systolic blood pressure decreased over time significantly more in females than in males. Throughout the study spKt/V was significantly higher in females than in males, but it increased in patients of both genders. There were no gender differences for comorbidities, vascular access and the majority of laboratory findings except for higher serum levels of creatinine and CRP in men than in women. Relatively more females were treated with erythropoiesis stimulating agents and phosphate binders than males. Age and malignancy were selected as significant predictors of mortality for both genders, and, in addition, polycystic kidney disease, serum level of albumin and CRP for men, but spKt/V for women.

CONCLUSION

Some significant gender differences were observed throughout, while others appeared during the study but none of them were due to gender inequalities in the applied treatment.

Quality indicators in hemodialysis: A 5-year experience of national campaigns in France

BACKGROUND

End stage kidney disease (ESKD) is associated with increased morbidity and mortality. Hemodialysis (HD) is the main technique used for kidney replacement therapy. Dialyzed patients are expected to live less than one half as long as their counterparts without ESKD. Improving quality of care may help to improve mortality in this population.

METHODS

The French National Authority for Health has carried out three consecutive national campaigns over 5 years for the assessment of quality indicators (QCI) during HD. QCI included anemia management, iron status evaluation, nutritional status assessment, and annual transplantation access.

RESULTS

From 2013 to 2017, 227 health facilities participated, and 33,319 files were analyzed. Median age was 72 years old (IQR_25-75  = 61-81), and 58.25% of patients were men. Median time in HD was 39.4 months (IQR_25-75  = 20.7-72.7). Most of the patients underwent in-center HD (85.41%). Overweight and obese patients accounted, respectively, for 28.39% and 21.32%, and malnutrition was present in 38.61%. A contra-indication for renal transplantation was found in 68.3% of patients. All QCI improved over 5 years.

CONCLUSION

Developing QCI based on guidelines is crucial to assure appropriate care of HD patients. Repeating campaigns over 5 years in France improves the quality of care among physicians.

Update on Management of Cardiovascular Diseases in Women

Cardiovascular diseases (CVD) have a lower prevalence in women than men; although, a higher mortality rate and a poorer prognosis are more common in women. However, there is a misperception of CVD female risk since women have commonly been considered more protected so that the real threat is vastly underestimated. Consequently, female patients are more likely to be treated less aggressively, and a lower rate of diagnostic and interventional procedures is performed in women than in men. In addition, there are substantial sex differences in CVD, so different strategies are needed. This review aims to evaluate the main gender-specific approaches in CVD.

OUP accepted manuscript

The year 2021 was the last full year of Alberto Ortiz’s editorship at Clinical Kidney Journal (CKJ). On May 2022, Maria José Soler will start her term as the Editor-in-Chief. Over these years, CKJ obtained its first journal impact factor and has consolidated its position among the top journals in the field, consistently ranking among the top 25% (first quartile) journals in Urology and Nephrology. The 2020 journal impact factor rose to 4.45, becoming the top open access journal in Nephrology and the ninth ranked Nephrology journal overall. We now review the recent history of the journal and the most highly cited topics which include the epidemiology of kidney disease, chronic kidney disease topics, such as the assessment and treatment of chronic kidney disease, onconephrology, cardionephrology, glomerular disease, transplantation and coronavirus disease 2019 (COVID-19).

Are sex differences in the outcome of peritoneal dialysis explained by nurse-assistance? A cohort study with data from the RDPLF

BACKGROUND

We aimed to evaluate sex differences in peritoneal dialysis (PD) outcomes and to explore direct and indirect effects of nurse-assisted PD on outcomes.

METHODS

This was a retrospective study using data from the French Language Peritoneal Dialysis Registry of incident PD patients between 2005 and 2016. Cox proportional hazard modelling was used to analyse transfer to haemodialysis (HD), death, PD failure, peritonitis and renal transplantation. Mediation analyses with a counterfactual approach were carried out to evaluate natural direct and indirect effects of sex on transfer to HD and peritonitis, with nurse-assisted PD as a mediator a priori.

RESULTS

Of the 14659 patients included, they were 5970 females (41%) and 8689 males (59%). Women were more frequently treated by nurse-assisted PD than men ((2926/5970 (49.1%) vs. 3357/8689 (38.7%)). In the multivariable analysis, women had a lower risk of transfer to HD (cause-specific hazard ratio(cs-HR): 0.82[95% confidence interval(CI): 0.77-0.88]), death (cs-HR: 0.90[95%CI: 0.85-0.95]), peritonitis (cs-HR: 0.82[95%CI: 0.78-0.87]), PD failure (cs-HR: 0.86[95%CI: 0.83-0.90]) and a lower chance of undergoing transplant (cs-HR: 0.83[95%CI: 0.77-0.90]) than men. There was a direct effect of sex on the risk of transfer to HD (cs-HR: 0.82[95%CI: 0.82-0.83]) with an indirect effect of nurse-assisted PD (cs-HR: 0.97[95%CI: 0.96-0.99]). Nurse-assisted PD had no indirect effect on the risk of peritonitis.

CONCLUSIONS

Our results suggest that compared with men, women have both a lower risk of transfer to HD and peritonitis. Mediation analysis showed that nurse assistance was a potential mediator in the causal pathway between sex and transfer to HD.

Renin-angiotensin system and inflammation update

The most classical view of the renin-angiotensin system (RAS) emphasizes its role as an endocrine regulator of sodium balance and blood pressure. However, it has long become clear that the RAS has pleiotropic actions that contribute to organ damage, including modulation of inflammation. Angiotensin II (Ang II) activates angiotensin type 1 receptors (AT1R) to promote an inflammatory response and organ damage. This represents the pathophysiological basis for the successful use of RAS blockers to prevent and treat kidney and heart disease. However, other RAS components could have a built-in capacity to brake proinflammatory responses. Angiotensin type 2 receptor (AT2R) activation can oppose AT1R actions, such as vasodilatation, but its involvement in modulation of inflammation has not been conclusively proven. Angiotensin-converting enzyme 2 (ACE2) can process Ang II to generate angiotensin-(1-7) (Ang-(1-7)), that activates the Mas receptor to exert predominantly anti-inflammatory responses depending on the context. We now review recent advances in the understanding of the interaction of the RAS with inflammation. Specific topics in which novel information became available recently include intracellular angiotensin receptors; AT1R posttranslational modifications by tissue transglutaminase (TG2) and anti-AT1R autoimmunity; RAS modulation of lymphoid vessels and T lymphocyte responses, especially of Th17 and Treg responses; interactions with toll-like receptors (TLRs), programmed necrosis, and regulation of epigenetic modulators (e.g. microRNAs and bromodomain and extraterminal domain (BET) proteins). We additionally discuss an often overlooked effect of the RAS on inflammation which is the downregulation of anti-inflammatory factors such as klotho, peroxisome proliferator-activated receptor γ co-activator 1α (PGC-1α), transient receptor potential ankyrin 1 (TRPA1), SNF-related serine/threonine-protein kinase (SNRK), serine/threonine-protein phosphatase 6 catalytic subunit (Ppp6C) and n-acetyl-seryl-aspartyl-lysyl-proline (Ac-SDKP). Both transcription factors, such as nuclear factor κB (NF-κB), and epigenetic regulators, such as miRNAs are involved in downmodulation of anti-inflammatory responses. A detailed analysis of pathways and targets for downmodulation of anti-inflammatory responses constitutes a novel frontier in RAS research.

Using datasets to ascertain the generalisability of clinical cohorts: the example of European QUALity Study on the treatment of advanced chronic kidney disease (EQUAL)

BACKGROUND

Cohort studies are among the most robust of observational studies but have issues with external validity. This study assesses threats to external validity (generalisability) in the European QUALity (EQUAL) study, a cohort study of people over 65 years with stage 4/5 chronic kidney disease.

METHODS

Patients meeting the EQUAL inclusion criteria were identified in The Health Improvement Network database and stratified into those attending renal units (secondary care cohort-SCC) and not (primary care cohort-PCC). Survival, progression to renal replacement therapy (RRT), and hospitalisation were compared.

RESULTS

The analysis included 250, 633, and 2,464 patients in EQUAL, PCC, and SCC. EQUAL had a higher proportion of men in comparison to PCC and SCC (60.0% vs. 34.8% vs. 51.4%). Increasing age (≥85 years odds ratio (OR) 0.25 (95% confidence interval (CI) 0.15-0.40)) and comorbidity (Charlson Comorbidity Index ≥ 4 OR 0.69 (CI 0.52-0.91)) were associated with non-participation in EQUAL. EQUAL had a higher proportion of patients starting RRT at 1 year compared to SCC (8.1% vs. 2.1%%, p < 0.001). Patients in the PCC and SCC had increased risk of Hospitalisation (incidence rate ratio=1.76 (95% CI 1.27-2.47) & 2.13 (95% CI 1.59-2.86)) and mortality at one year (hazard ratio=3.48 (95% CI 2.1-5.7) & 1.7 (95% CI 1.1-2.7)) compared to EQUAL.

CONCLUSIONS

This study provides evidence of how participants in a cohort study can differ from the broader population of patients, which is essential when considering external validity and applying to local practice.

The unaccomplished mission of reducing mortality in patients on kidney replacement therapy

Six years ago, a comprehensive review by the EURECA-m working group of the ERA-EDTA thoroughly addressed the drivers of mortality in patients with end-stage kidney disease. Not unexpectedly, the key global driver of early death in these patients was the lack of access to kidney replacement therapy. However, and contrary to the expectations of non-nephrologists, mortality was still high when kidney replacement therapy was provided. This was due to excess cardiovascular and non-cardiovascular mortality, and the need to further characterize correctable risk factors and eventually test the impact of correcting them was emphasized. In this issue of ckj, seven reports address risk factors for death in non-dialysis chronic kidney disease (CKD), dialysis and kidney transplant patients. They characterize irreversible (e.g. sex; age; genetic variants of the KL gene encoding the anti-ageing protein Klotho) and reversible (obesity; mineral and bone disorder parameters; anti-depressant drugs, especially those that increase the QT; amputation; public health investments) factors associated with mortality of CKD patients on or off kidney replacement therapy.

Sex Differences in Time-Series Changes in Pseudo-R2 Values Regarding Hyperuricemia in Relation to the Kidney Prognosis

Studies on sex differences in time-series changes in pseudo-R² values regarding hyperuricemia (HU) in relation to the kidney prognosis among patients with chronic kidney disease (CKD) are scant. The kidney prognosis was evaluated in 200 patients with CKD (median follow-up, 12.3 years). Survival analyses and logistic regression analyses were conducted, generating time-series pseudo-R² values. We used four definitions of HU according to serum uric acid (SUA) levels (HU6, SUA ≥ 6.0 mg/dL; HU7, SUA ≥ 7.0 mg/dL; HU8, SUA ≥ 8.0 mg/dL) and antihyperuricemic agent use to calculate the mean and percentage of the change in pseudo-R² values from the 6th year until the end of the study (6Y–End Mean and 6Y–End Change, respectively). The multivariable Cox regression analysis showed that HU7 was significantly associated with kidney outcomes. When stratified by sex, the 6Y–End Mean was clearly higher in women than in men for all HU definitions, with the highest value (0.1755) obtained for HU7 in women. The pseudo-R² values for HU6 in women showed an increasing pattern, with a 6Y–End Change of 11.4%/year. Thus, it may be clinically meaningful to consider sex differences in the time-series pseudo-R² values regarding HU and kidney outcomes.

Sex disparities in dialysis initiation, access to waitlist, transplantation and transplant outcome in German patients with renal disease-A population based analysis

Background

Renal transplantation access and outcome differ between men and women, but no analysis has considered all transition phases and transplant outcome using the same data set. We analyzed sex disparities in all phases of patients’ clinical path (progression to dialysis, waitlisting, transplantation, graft failure/death).

Methods

In a population based approach using health insurance data (2005–2013) we examined patients’ risk of changing from one phase to another applying Cox Proportional Hazards model.

Results

After adjusting for age and comorbidities, women had a 16% lower risk of progression to ESRD (HR/95%-CI: 0.84/0.79–0.88). Access to the waitlist was lowered by 18% in women compared to men (HR/95%-CI: 0.82/0.70–0.96). An age stratified analysis did not reveal differences in any age group. Once waitlisted, the chance to receive a transplant was identical (HR/95%-CI: 0.96/0.81–1.15). The risk of transplant failure/death was identical for both sexes (HR/95%-CI: 0.99/0.73–1.35), but the effect was modified by age: in younger women (18–45 years) the risk was twice as high compared to men (HR/95%-CI: 2.08/1.04–4.14), whereas the risk in elderly women (> 65 years) was only half the risk of men (HR/95%-CI: 0.47/0.24–0.93).

Conclusion

Sex disparities occurred at different steps in the history of patients with renal disease and affected progression to dialysis, waitlisting and transplantation outcome in a population with equal access to medical treatment.

Advocacy for renal replacement therapy: the role of renal registries

The paper by Jardine et al. reporting results from the South African Renal Registry describes a 2-fold success. First, even in a limited-resource environment, survival of patients on renal replacement therapy (RRT) is favourable. Secondly, this information is available because a few years ago, South African nephrologists started a renal registry. These successes cannot conceal, however, that numerous patients are not offered RRT. Robust health information systems make it possible to define chronic kidney disease and end-stage kidney disease (ESKD) burdens, guide resource allocation, inform service planning and enable policy. Registries can highlight inequitable RRT access and help support advocacy in favour of additional resources for ESKD care.

The dirty little secret of urate-lowering therapy: useless to stop chronic kidney disease progression and may increase mortality

Hyperuricaemia is frequent in chronic kidney disease (CKD). Observational studies have shown an association with adverse outcomes and acquired hyperuricaemia (meaning serum urate levels as low as 1.0 mg/dL) in animal models induces kidney injury. This evidence does not justify the widespread use of urate-lowering drugs for asymptomatic hyperuricaemia in CKD. However, promising results from small, open-label studies led some physicians to prescribe urate-lowering drugs to slow CKD progression. Two recent, large, placebo-controlled trials (CKD-FIX and PERL) showed no benefit from urate lowering with allopurinol on the primary endpoint of CKD progression, confirming prior negative results. Despite these negative findings, it was still argued that the study population could be optimized by enrolling younger non-proteinuric CKD patients with better preserved glomerular filtration rate (GFR). However, in these low-risk patients, GFR may be stable under placebo conditions. Additionally, the increased mortality trends already identified in gout trials of urate-lowering therapy were also observed in CKD-FIX and PERL, sending a strong safety signal: 21/449 (4.7%) and 10/444 (2.2%) patients died in the combined allopurinol and placebo groups, respectively [chi-squared P-value 0.048; relative risk 2.07 (95% CI 0.98–4.34); P = 0.06]. Given the absent evidence of benefit in multiple clinical trials and the potentially serious safety issues, the clear message should be that urate-lowering therapy should not be prescribed for the indication of slowing CKD progression. Additionally, regulatory agencies should urgently reassess the safety of chronic prescription of urate-lowering drugs for any indication.

Optimizing the timing of nephrology referral for patients with diabetic kidney disease

Age-standardized rates of diabetes mellitus (DM)-related complications, such as acute myocardial infarction, stroke or amputations, have decreased in recent years, but this was not associated with a clear reduction of the incidence of advanced chronic kidney disease (CKD) requiring renal replacement therapy. The early detection of diabetic kidney disease (DKD) is a key to reduce complications, morbidity and mortality. Consensus documents and clinical practice guidelines recommend referral of DM patients to nephrology when the estimated glomerular filtration rate falls below 30 mL/min/1.73 m² or when albuminuria exceeds 300 mg/g urinary creatinine. Conceptually, it strikes as odd that patients with CKD are referred to the specialist caring for the prevention and treatment of CKD only when >70% of the functioning kidney mass has been lost. The increasing global health burden of CKD, driven in large part by DKD, the suboptimal impact of routine care on DKD outcomes as compared with other DM complications, the realization that successful therapy of CKD requires early diagnosis and intervention, the advances in earlier diagnosis of kidney injury and the recent availability of antidiabetic drugs with a renal mechanism of action and lack of hypoglycaemia risk, which additionally are cardio- and nephroprotective, all point towards a paradigm shift in the care for DM patients in which they should be referred earlier to nephrology as part of a coordinated and integrated care approach.

Gender, Albuminuria and Chronic Kidney Disease Progression in Treated Diabetic Kidney Disease

BACKGROUND

Women are reported to have a lower incidence of renal replacement therapy, despite a higher prevalence of chronic kidney disease (CKD).

AIM

To analyze diabetic kidney disease (DKD) progression in men and women.

METHODS

Prospective cohort: n = 261, 35% women, new consecutive nephrology DKD referrals.

RESULTS

Women smoked less and better complied with the dietary phosphate and sodium restrictions. Despite a less frequent nephrology referral, women had lower baseline albuminuria. Over a 30 ± 10-month follow-up, albuminuria decreased in women and the estimated glomerular filtration rate (eGFR) loss was slower than in men. However, the percentage of rapid progressors was similar in both sexes. The best multivariate model predicting rapid progression in men (area under curve (AUC) = 0.92) and women differed. Albuminuria and fractional excretion of phosphate (FEphosphate) were part of the men multivariable model, but not of women. The AUC for the prediction of rapid progression by albuminuria was higher in men than in women, and the albuminuria cut-off points also differed. In women, there was a higher percentage of rapid progressors who had baseline physiological albuminuria.

CONCLUSIONS

Female DKD differs from male DKD: albuminuria was milder and better responsive to therapy, the loss of eGFR was slower and the predictors of rapid progression differed from men: albuminuria was a better predictor in men than in women. Lifestyle factors may contribute to the differences.

Sex hormones and their influence on chronic kidney disease

PURPOSE OF REVIEW

The majority of end-stage renal disease including dialysis and kidney transplant patients are men. In contrast, the incidence of chronic kidney disease (CKD) is higher in women compared with men. In this review, we dissect the sex hormone levels and its effects on experimental models and patients with CKD.

RECENT FINDINGS

Sex hormones are clearly involved in CKD progression to end-stage renal disease (ESRD). A significant reduction in lipid peroxidation as a mechanism of renoprotection has been observed in kidneys of streptozotocin (STZ)-diabetic ovariectomized rats after estradiol administration. Furthermore, a G-protein-coupled estrogen receptor inhibits podocyte oxidative stress maintaining the integrity of the mitochondrial membrane. Sex hormone depletion has been shown to modulate RAS system and protect against kidney injury in the male STZ-diabetic model. In human primary proximal tubular epithelial cells, a proteomic study showed that dihydrotestosterone dysregulated metabolic, suggesting that the deleterious effect of androgens within the kidney maybe related to altered energy metabolism in renal tubules.

SUMMARY

Male gender is associated with worse CKD progression and this fact may be ascribed to sex hormone. Although male hormones exert a deleterious effect in terms of increasing oxidative stress, activating RAS system, and worsening fibrosis within the damaged kidney, female hormones exert a renoprotective effect.

Meso-American nephropathy: what we have learned about the potential genetic influence on chronic kidney disease development

Chronic kidney disease of unknown aetiology (CKDu) refers to the epidemic level of incidence of CKD in several low- and middle-income countries, usually near the equator, for which the aetiology has not been identified. CKDu represents a form of CKD hotspot, defined as a country, region, community or ethnicity with a higher than average incidence of CKD. In terms of the number of persons affected, the so-called hypertensive nephropathy of African Americans probably represents the largest CKD hotspot, which is largely driven by variants of the APOL1 gene, questioning the very existence of hypertensive nephropathy and illustrating how kidney disease driven by genetic predisposition may underlie some forms of hypertension. For CKDu, hard physical work leading to dehydration (the first global warming-related disease?) and local toxins are leading aetiological candidates. Meso-American nephropathy is probably the best-characterized CKDu. In this issue of CKJ, a systematic review and meta-analysis by Gonzalez et al. identified positive associations between Meso-American nephropathy and male gender, family history of CKD, high water intake and lowland altitude. We now discuss the potential relationship of family history to genetic predisposition and how a better understanding of CKDu may help advance the aetiological characterization of the nearly 50% of end-stage renal disease patients worldwide that have no known cause for CKD or have been assigned non-specific diagnoses.