Background. Patients with chronic kidney disease (CKD) are at a higher risk of major adverse cardiovascular events (MACE) compared with the general population, but gender differences in this risk,... Show moreBackground. Patients with chronic kidney disease (CKD) are at a higher risk of major adverse cardiovascular events (MACE) compared with the general population, but gender differences in this risk, especially in older adults, are not fully known. We aim to identify gender differences in the risk of MACE in older European CKD patients, and explore factors that may explain these differences.Methods. The European Quality study (EQUAL) is a prospective study on stage 4-5 CKD patients, >= 65 years old, not on dialysis, from Germany, Italy, the Netherlands, Poland, Sweden and the UK. Cox regression and cumulative incidence competing risk curves were used to identify gender differences in MACE risks. Mediation analysis was used to identify variables which may explain risk differences between men and women.Results. A total of 417 men out of 1134 (37%) and 185 women out of 602 women (31%) experienced at least one MACE, over a follow-up period of 5 years. Women had an 18% lower risk of first MACE compared with men (hazard ratio 0.82; 95% confidence interval 0.69-0.97; P =.02), which was attenuated after adjusting for pre-existing cardiometabolic comorbidities and cardiovascular risk factors. There were no significant gender differences in the risk of recurrent MACE or fatal MACE. The risk difference in MACE by gender was larger in patients aged 65-75 years, compared with patients over 75 years.Conclusions. In a cohort of older adults with advanced CKD, women had lower risks of MACE. These risk differences were partially explained by pre-existing cardiometabolic comorbidities and cardiovascular risk factors.[GRAPHICS]. Show less
Lay Summary Our study compared the incidence of dialysis, the most common treatment modality for kidney failure, in the Netherlands with 11 other European countries/regions between 2001 and 2019.... Show moreLay Summary Our study compared the incidence of dialysis, the most common treatment modality for kidney failure, in the Netherlands with 11 other European countries/regions between 2001 and 2019. We observed a decline in the dialysis incidence in the last decade, most marked among patients aged >= 65 years. Similar trends were found in Austria, Denmark, England/Wales, Finland, Scotland, and Sweden. Although the number of kidney transplantations increased significantly, this can only explain a minor part of the observed decrease in the dialysis incidence among these older patients. An increase in the number of patients choosing to forego dialysis (i.e. conservative care) or improvement of preventive care for cardiovascular- or kidney disease, are likely explanations. Our study stresses the need for registration of patients with earlier stages of chronic kidney disease and patients that choose conservative care. This would allow for better assessment of healthcare utilization and outcomes in these patient groups.Introduction After decades of increasing dialysis incidence, we observed a decreasing trend in the Netherlands in the last decade. We compared this trend with trends in other European countries. Materials and Methods Aggregated data for calendar years 2001-2019 from the Dutch registries of kidney replacement therapy patients and the European Renal Association Registry were used. Dialysis incidence in the Netherlands was compared with that in 11 other European countries/regions using three age groups: 20-64, 65-74, and >= 75 years, taking into account pre-emptive kidney transplantation (PKT) incidence. Time trends were assessed as annual percentage change (APC) with 95% confidence intervals (CI) using joinpoint regression analysis. Results Between 2001 and 2019 the Dutch dialysis incidence decreased slightly among patients aged 20-64 years (APC -0.9, 95% CI -1.4; -0.5). For patients 65-74 and >= 75 years old, a peak was seen in 2004 and 2009, respectively. Afterwards, the decrease was most marked in patients aged >= 75 years: APC -3.2 (-4.1; -2.3) versus APC -1.8 (-2.2; -1.3) for patients 65-74 years old. PKT incidence increased significantly during the study period but remained limited compared to the observed decrease in dialysis incidence, especially among older patients. Large differences in dialysis incidence were observed among European countries/regions. A decreasing dialysis incidence among older patients was also seen in Austria, Denmark, England/Wales, Finland, Scotland, and Sweden. Conclusions The Dutch dialysis incidence decreased most profoundly among older patients. This was also observed in several other European countries/regions. Although PKT incidence increased, it can only explain a minor part of the decrease in dialysis incidence. Show less
Background In the general population with coronavirus disease 2019 (COVID-19), obesity is associated with an increased risk of mortality. Given the typically observed obesity paradox among patients... Show moreBackground In the general population with coronavirus disease 2019 (COVID-19), obesity is associated with an increased risk of mortality. Given the typically observed obesity paradox among patients on kidney function replacement therapy (KFRT), especially dialysis patients, we examined the association of obesity with mortality among dialysis patients or living with a kidney transplant with COVID-19. Methods Data from the European Renal Association COVID-19 Database (ERACODA) were used. KFRT patients diagnosed with COVID-19 between 1 February 2020 and 31 January 2021 were included. The association of Quetelet's body mass index (BMI) (kg/m(2)), divided into: <18.5 (lean), 18.5-24.9 (normal weight), 25-29.9 (overweight), 30-34.9 (obese I) and >= 35 (obese II/III), with 3-month mortality was investigated using Cox proportional-hazards regression analyses. Results In 3160 patients on KFRT (mean age: 65 years, male: 61%), 99 patients were lean, 1151 normal weight (reference), 1160 overweight, 525 obese I and 225 obese II/III. During follow-up of 3 months, 28, 20, 21, 23 and 27% of patients died in these categories, respectively. In the fully adjusted model, the hazard ratios (HRs) for 3-month mortality were 1.65 [95% confidence interval (CI): 1.10, 2.47], 1 (ref.), 1.07 (95% CI: 0.89, 1.28), 1.17 (95% CI: 0.93, 1.46) and 1.71 (95% CI: 1.27, 2.30), respectively. Results were similar among dialysis patients (N = 2343) and among those living with a kidney transplant (N = 817) (P-interaction = 0.99), but differed by sex (P-interaction = 0.019). In males, the HRs for the association of aforementioned BMI categories with 3-month mortality were 2.07 (95% CI: 1.22, 3.52), 1 (ref.), 0.97 (95% CI: 0.78. 1.21), 0.99 (95% CI: 0.74, 1.33) and 1.22 (95% CI: 0.78, 1.91), respectively, and in females corresponding HRs were 1.34 (95% CI: 0.70, 2.57), 1 (ref.), 1.31 (95% CI: 0.94, 1.85), 1.54 (95% CI: 1.05, 2.26) and 2.49 (95% CI: 1.62, 3.84), respectively. Conclusion In KFRT patients with COVID-19, on dialysis or a kidney transplant, obesity is associated with an increased risk of mortality at 3 months. This is in contrast to the obesity paradox generally observed in dialysis patients. Additional studies are required to corroborate the sex difference in the association of obesity with mortality. Show less
Maarse, B.C.E.; Chesnaye, N.C.; Schouten, R.; Michels, W.M.; Bos, W.J.W.; Szymczak, M.; ... ; EQUAL Study Investigators 2022
Background: Depressive symptoms are associated with adverse clinical outcomes in patients with end-stage kidney disease; however, few small studies have examined this association in patients with... Show moreBackground: Depressive symptoms are associated with adverse clinical outcomes in patients with end-stage kidney disease; however, few small studies have examined this association in patients with earlier phases of chronic kidney disease (CKD). We studied associations between baseline depressive symptoms and clinical outcomes in older patients with advanced CKD and examined whether these associations differed depending on sex. Methods: CKD patients (>= 65 years; estimated glomerular filtration rate <= 20 mL/min/1.73 m(2)) were included from a European multicentre prospective cohort between 2012 and 2019. Depressive symptoms were measured by the five-item Mental Health Inventory (cut-off <= 70; 0-100 scale). Cox proportional hazard analysis was used to study associations between depressive symptoms and time to dialysis initiation, all-cause mortality and these outcomes combined. A joint model was used to study the association between depressive symptoms and kidney function over time. Analyses were adjusted for potential baseline confounders. Results: Overall kidney function decline in 1326 patients was -0.12 mL/min/1.73 m(2)/month. A total of 515 patients showed depressive symptoms. No significant association was found between depressive symptoms and kidney function over time (P = 0.08). Unlike women, men with depressive symptoms had an increased mortality rate compared with those without symptoms [adjusted hazard ratio 1.41 (95% confidence interval 1.03-1.93)]. Depressive symptoms were not significantly associated with a higher hazard of dialysis initiation, or with the combined outcome (i.e. dialysis initiation and all-cause mortality). Conclusions: There was no significant association between depressive symptoms at baseline and decline in kidney function over time in older patients with advanced CKD. Depressive symptoms at baseline were associated with a higher mortality rate in men. Show less
Janse, R.J.; Hoekstra, T.; Jager, K.J.; Zoccali, C.; Tripepi, G.; Dekker, F.W.; Diepen, M. van 2021
The correlation coefficient is a statistical measure often used in studies to show an association between variables or to look at the agreement between two methods. In this paper, we will discuss... Show moreThe correlation coefficient is a statistical measure often used in studies to show an association between variables or to look at the agreement between two methods. In this paper, we will discuss not only the basics of the correlation coefficient, such as its assumptions and how it is interpreted, but also important limitations when using the correlation coefficient, such as its assumption of a linear association and its sensitivity to the range of observations. We will also discuss why the coefficient is invalid when used to assess agreement of two methods aiming to measure a certain value, and discuss better alternatives, such as the intraclass coefficient and Bland-Altman's limits of agreement. The concepts discussed in this paper are supported with examples from literature in the field of nephrology. Show less
Fu, E.L.; Diepen, M. van; Xu, Y.; Trevisan, M.; Dekker, F.W.; Zoccali, C.; ... ; Carrero, J.J. 2021
Observational pharmacoepidemiological studies using routinely collected healthcare data are increasingly being used in the field of nephrology to answer questions on the effectiveness and safety of... Show moreObservational pharmacoepidemiological studies using routinely collected healthcare data are increasingly being used in the field of nephrology to answer questions on the effectiveness and safety of medications. This review discusses a number of biases that may arise in such studies and proposes solutions to minimize them during the design or statistical analysis phase. We first describe designs to handle confounding by indication (e.g. active comparator design) and methods to investigate the influence of unmeasured confounding, such as the E-value, the use of negative control outcomes and control cohorts. We next discuss prevalent user and immortal time biases in pharmacoepidemiology research and how these can be prevented by focussing on incident users and applying either landmarking, using a time-varying exposure, or the cloning, censoring and weighting method. Lastly, we briefly discuss the common issues with missing data and misclassification bias. When these biases are properly accounted for, pharmacoepidemiological observational studies can provide valuable information for clinical practice. Show less
Randomized controlled trials on drug safety and effectiveness are the foundation of medical evidence, but they may have limited generalizability and be unpowered to detect rare and long-term kidney... Show moreRandomized controlled trials on drug safety and effectiveness are the foundation of medical evidence, but they may have limited generalizability and be unpowered to detect rare and long-term kidney outcomes. Observational studies in routine care data can complement and expand trial evidence on the use, safety and effectiveness of medications and aid with clinical decisions in areas where evidence is lacking. Access to routinely collected large healthcare data has resulted in the proliferation of studies addressing the effect of medications in patients with kidney diseases and this review provides an introduction to the science of pharmacoepidemiology to critically appraise them. In this first review we discuss the concept and applications of pharmacoepidemiology, describing methods for drug-utilization research and discussing the strengths and caveats of the most commonly used study designs to evaluate comparative drug safety and effectiveness. Show less
Ramspek, C.L.; Jager, K.J.; Dekker, F.W.; Zoccali, C.; Diepen, M. van 2021
Prognostic models that aim to improve the prediction of clinical events, individualized treatment and decision-making are increasingly being developed and published. However, relatively few models... Show morePrognostic models that aim to improve the prediction of clinical events, individualized treatment and decision-making are increasingly being developed and published. However, relatively few models are externally validated and validation by independent researchers is rare. External validation is necessary to determine a prediction model's reproducibility and generalizability to new and different patients. Various methodological considerations are important when assessing or designing an external validation study. In this article, an overview is provided of these considerations, starting with what external validation is, what types of external validation can be distinguished and why such studies are a crucial step towards the clinical implementation of accurate prediction models. Statistical analyses and interpretation of external validation results are reviewed in an intuitive manner and considerations for selecting an appropriate existing prediction model and external validation population are discussed. This study enables clinicians and researchers to gain a deeper understanding of how to interpret model validation results and how to translate these results to their own patient population. Show less
Schroijen, M.A.; Diepen, M. van; Hamming, J.F.; Dekker, F.W.; Dekkers, O.M.; NECOSAD Study Grp 2020
Background: Survival among dialysis patients with diabetes mellitus (DM) is inferior to survival of non-diabetic dialysis patients, probably due to the higher prevalence of diabetes-related... Show moreBackground: Survival among dialysis patients with diabetes mellitus (DM) is inferior to survival of non-diabetic dialysis patients, probably due to the higher prevalence of diabetes-related comorbid conditions. One could hypothesize that these comorbid conditions also contribute to a decreased survival after amputation in diabetic patients compared with non-diabetic patients on dialysis.Methods: Data were collected from the Netherlands Cooperative Study on the Adequacy of Dialysis, a multicentre, prospective cohort study in which new patients with end-stage renal disease were monitored until transplantation or death. Amputation rates (incident cases) were calculated in patients with and without DM. The primary endpoint was all-cause survival after first amputation during dialysis therapy in diabetic patients compared with non-diabetic dialysis patients with an amputation. This was formally assessed using interaction analysis (Poisson regression).Results: During follow-up (mean duration 2.9 years), 50 of the 413 diabetic patients had a new amputation (12.1%), compared with 20 of 1553 non-diabetic patients (1.2%). Amputation rates/1000 person-years were 47.9 [95% confidence interval (CI) 36.3-63.2] and 4.1 (95% CI 2.7-6.4), respectively, for diabetic patients and non-diabetic patients. Amputation increased mortality risk more than 4-fold in patients without diabetes [hazard ratio (HR) 4.6 (95% CI 2.8-7.6)] as well as in patients with diabetes [HR 4.6 (95% CI 3.3-6.4)]. No formal interaction between diabetes and amputation was found (P = 0.12).Conclusions: Amputation in dialysis patients is associated with a 4-fold increased mortality risk; this mortality risk was similar for diabetes and non-diabetes patients. Importantly, the risk for amputation is 10-fold higher in DM compared with non-diabetic dialysis patients. Show less
Potassiumoften has a negative connotation in Nephrology as patients with chronic kidney disease (CKD) are prone to develop hyperkalaemia. Approaches to the management of chronic hyperkalaemia... Show morePotassiumoften has a negative connotation in Nephrology as patients with chronic kidney disease (CKD) are prone to develop hyperkalaemia. Approaches to the management of chronic hyperkalaemia include a low potassium diet or potassiumbinders. Yet, emerging data indicate that dietary potassium may be beneficial for patients with CKD. Epidemiological studies have shown that a higher urinary potassium excretion (as proxy for higher dietary potassium intake) is associated with lower blood pressure (BP) and lower cardiovascular risk, as well as better kidney outcomes. Considering that the composition of our current diet is characterized by a high sodium and low potassium content, increasing dietary potassium may be equally important as reducing sodium. Recent studies have revealed that dietary potassiummodulates the activity of the thiazide-sensitive sodium-chloride cotransporter in the distal convoluted tubule (DCT). The DCT acts as a potassium sensor to control the delivery of sodium to the collecting duct, the potassium-secreting portion of the kidney. Physiologically, this allows immediate kaliuresis after a potassium load, and conservation of potassiumduring potassium deficiency. Clinically, it provides a novel explanation for the inverse relationship between dietary potassium and BP. Moreover, increasing dietary potassium intake can exert BP-independent effects on the kidney by relieving the deleterious effects of a low potassium diet (inflammation, oxidative stress and fibrosis). The aim of this comprehensive review is to link physiology with clinical medicine by proposing that the same mechanisms that allow us to excrete an acute potassiumload also protect us from hypertension, cardiovascular disease and CKD. Show less
Fu, E.L.; Janse, R.J.; Jong, Y. de; Endt, V.H.W. van der; Milders, J.; Willik, E.M. van der; ... ; Diepen, M. van 2020
Background. Acute kidney injury (AKI) can affect hospitalized patients with coronavirus disease 2019 (COVID-19), with estimates ranging between 0.5% and 40%. We performed a systematic review and... Show moreBackground. Acute kidney injury (AKI) can affect hospitalized patients with coronavirus disease 2019 (COVID-19), with estimates ranging between 0.5% and 40%. We performed a systematic review and meta-analysis of studies reporting incidence, mortality and risk factors for AKI in hospitalized COVID-19 patients.Methods. We systematically searched 11 electronic databases until 29 May 2020 for studies in English reporting original data on AKI and kidney replacement therapy (KRT) in hospitalized COVID-19 patients. Incidences of AKI and KRT and risk ratios for mortality associated with AKI were pooled using generalized linear mixed and random-effects models. Potential risk factors for AKI were assessed using meta-regression. Incidences were stratified by geographic location and disease severity.Results. A total of 3042 articles were identified, of which 142 studies were included, with 49 048 hospitalized COVID-19 patients including 5152 AKI events. The risk of bias of included studies was generally low. The pooled incidence of AKI was 28.6% [95% confidence interval (CI) 19.8-39.5] among hospitalized COVID-19 patients from the USA and Europe (20 studies) and 5.5% (95% CI 4.1-7.4) among patients from China (62 studies), whereas the pooled incidence of KRT was 7.7% (95% CI 5.1-11.4; 18 studies) and 2.2% (95% CI 1.5-3.3; 52 studies), respectively. Among patients admitted to the intensive care unit, the incidence of KRT was 20.6% (95% CI 15.7-26.7; 38 studies). Meta-regression analyses showed that age, male sex, cardiovascular disease, diabetes mellitus, hypertension and chronic kidney disease were associated with the occurrence of AKI; in itself, AKI was associated with an increased risk of mortality, with a pooled risk ratio of 4.6 (95% CI 3.3-6.5).Conclusions. AKI and KRT are common events in hospitalized COVID-19 patients, with estimates varying across geographic locations. Additional studies are needed to better understand the underlying mechanisms and optimal treatment of AKI in these patients. Show less
Background. Posterior urethral valves (PUV) account for 17% of paediatric end-stage renal disease. A major issue in the management of PUV is prenatal prediction of postnatal renal function. Fetal... Show moreBackground. Posterior urethral valves (PUV) account for 17% of paediatric end-stage renal disease. A major issue in the management of PUV is prenatal prediction of postnatal renal function. Fetal ultrasound and fetal urine biochemistry are currently employed for this prediction, but clearly lack precision. We previously developed a fetal urine peptide signature that predicted in utero with high precision postnatal renal function in fetuses with PUV. We describe here the objectives and design of the prospective international multicentre ANTENATAL (multicentre validation of a fetal urine peptidome-based classifier to predict postnatal renal function in posterior urethral valves) study, set up to validate this fetal urine peptide signature.Methods. Participants will be PUV pregnancies enrolled from 2017 to 2021 and followed up until 2023 in >30 European centres endorsed and supported by European reference networks for rare urological disorders (ERN eUROGEN) and rare kidney diseases (ERN ERKNet). The endpoint will be renal/patient survival at 2 years postnatally. Assuming a = 0.05, 1-b = 0.8 and a mean prevalence of severe renal outcome in PUV individuals of 0.35, 400 patients need to be enrolled to validate the previously reported sensitivity and specificity of the peptide signature.Results. In this largest multicentre study of antenatally detected PUV, we anticipate bringing a novel tool to the clinic. Based on urinary peptides and potentially amended in the future with additional omics traits, this tool will be able to precisely quantify postnatal renal survival in PUV pregnancies. The main limitation of the employed approach is the need for specialized equipment.Conclusions. Accurate risk assessment in the prenatal period should strongly improve the management of fetuses with PUV. Show less
In nephrology, a great deal of information is measured repeatedly in patients over time, often alongside data on events of clinical interest. In this introductory article we discuss how these two... Show moreIn nephrology, a great deal of information is measured repeatedly in patients over time, often alongside data on events of clinical interest. In this introductory article we discuss how these two types of data can be simultaneously analysed using the joint model (JM) framework, illustrated by clinical examples from nephrology. As classical survival analysis and linear mixed models form the two main components of the JM framework, we will also briefly revisit these techniques. Show less
