International comparison and time trends of first kidney transplant recipient characteristics across Europe: an ERA Registry study.

BACKGROUND: The aim of this study was to provide an overview of age, sex and primary renal disease (PRD) distribution among first kidney transplant recipients across Europe. METHOD: The European Renal Association (ERA) Registry database was used to obtain data on patients aged 20 years or older receiving their first kidney transplant between 2010 and 2019 from 12 European countries. The numbers and percentages of recipients in each age, sex and PRD group were calculated by country, donor type and year. RESULTS: In total, 99 543 adults received a first kidney transplant. Overall, 23% of the recipients were 65 years or older, 36% were female, and 21% had glomerulonephritis and 15% diabetes mellitus as PRD. Compared with deceased donor kidney transplant recipients, living donor kidney transplant recipients were less often 65 years or older (13% versus 26%), more often had glomerulonephritis (25% versus 20%) and less often diabetes mellitus (8% versus 17%) as PRD. We found large international differences, which were most prominent for age and PRD and less prominent for sex. Over time, the largest change in recipient characteristics was observed for the percentage of recipients aged 65 years or older, increasing from 18% in 2010 to 28% in 2019 for all countries combined with a similar trend in most countries. CONCLUSION: We observed large differences for age and PRD distribution between recipients of living and deceased donor kidneys and between European countries. Over time, the percentage of older first kidney transplant recipients increased.

Incidence and outcomes of kidney replacement therapy for end-stage kidney disease due to primary glomerular disease in Europe: findings from the ERA Registry.

BACKGROUND AND HYPOTHESIS: Primary glomerular disease (PGD) is a major cause of end-stage kidney disease (ESKD) leading to kidney replacement therapy (KRT). We aimed to describe incidence (trends) in individuals starting KRT for ESKD due to PGD and to examine their survival and causes of death. METHODS: We used data from the European Renal Association (ERA) Registry on 69 854 patients who started KRT for ESKD due to PGD between 2000 and 2019. ERA primary renal disease codes were used to define six PGD subgroups. We examined age and sex standardized incidence, trend of the incidence, and survival. RESULTS: The standardized incidence of KRT for ESKD due to PGD was 16.6 per million population (pmp), ranging from 8.6 pmp in Serbia to 20.0 pmp in France. IgA nephropathy (IgAN) and focal segmental glomerulosclerosis (FSGS) had the highest incidence of 4.6 pmp and 2.6 pmp, respectively. Histologically non-examined PGDs represented over 50% of cases in Serbia, Bosnia and Herzegovina, and Romania and were also common in Greece, Estonia, Belgium, and Sweden. The incidence declined from 18.6 pmp in 2000 to 14.5 pmp in 2013, after which it stabilized. All PGD subgroups had five-year survival probabilities above 50%, with crescentic glomerulonephritis having the highest risk of death (adjusted hazard ratio: 1.8 [95% confidence interval: 1.6-1.9]) compared with IgAN. Cardiovascular disease was the most common cause of death (33.9%). CONCLUSION: The incidence of KRT for ESKD due to PGD showed large differences between countries and was highest and increasing for IgAN and FSGS. Lack of kidney biopsy facilities in some countries may have affected accurate assignment of the cause of ESKD. The recognition of the incidence and outcomes of KRT among different PGD subgroups may contribute to a more individualized patient care approach.

Changes in the epidemiology of kidney replacement therapy across Europe in 2020 - the first year of the COVID-19 pandemic: an ERA Registry study.

BACKGROUND: In 2020, the COVID-19 pandemic caused disruptions in kidney replacement therapy (KRT) services worldwide. The aim of this study was to assess the effect of the COVID-19 pandemic in 2020 on the incidence of KRT, kidney transplantation activity, mortality and prevalence of KRT across Europe. METHODS: Patients receiving KRT were included from 17 countries providing data to the European Renal Association Registry. The epidemiology of KRT in 2020 was compared with average data from the period 2017-2019. Also changes occurring during the first and second wave of the pandemic were explored. RESULTS: The incidence of KRT was 6.2% lower in 2020 compared with 2017-2019, with the lowest point (-22.7%) during the first wave in April. The decrease varied across countries, was smaller in males (-5.2%) than in females (-8.2%), and was moderate for peritoneal dialysis (-3.7%) and haemodialysis (-5.4%), but substantial for pre-emptive kidney transplantation (-23.6%). The kidney transplantation rate decreased by 22.5%, reaching a nadir of -80.1% during the first wave, and most for living donor kidney transplants (-30.5%). While in most countries the kidney transplantation rate decreased, in the Nordic/Baltic countries and Greece there was no clear decline. In dialysis patients, mortality increased by 11.4%, and was highest in those aged 65-74 years (16.1%), in those with diabetes as primary renal disease (15.1%), and in those on haemodialysis (12.4%). In transplant recipients, the mortality was 25.8% higher, but there were no subgroups that stood out. In contrast to the rising prevalence of KRT observed over the past decades across Europe, the prevalence at the end of 2020 (N=317787) resembled that of 2019 (N=317077). CONCLUSION: The COVID-19 pandemic has had a substantial impact on the incidence of KRT, kidney transplant activity, mortality of KRT, and prevalence of KRT in Europe with variations across countries.

Time trends in preemptive kidney transplantation in Europe: an era registry study.

BACKGROUND: Preemptive kidney transplantation has better outcomes when compared to transplantation after dialysis. We aimed to examine trends in preemptive kidney transplantation between 2000 and 2019 in Europe and to provide an overview of associated policies, barriers and initiatives. METHODS: Adult patients from 12 European countries who received a preemptive kidney transplant were included. The representatives of the registries providing these data were questioned on the policies, barriers and initiatives around preemptive kidney transplantation. RESULTS: Between 2000 and 2019, 20 251 adults underwent preemptive kidney transplantation (11 169 from living donors, 8937 from deceased donors). The proportion of first kidney transplantations that were preemptive more than doubled from 7% in 2000 to 18% in 2019, reflecting a similar relative increase for living donor kidney recipients (from 21% to 43%) and deceased donor kidney recipients (from 4% to 11%). Large international differences were found. The increase in preemptive kidney transplantation was observed across all age, sex and primary renal disease groups. Countries had similar criteria for preemptive waitlisting. Barriers mentioned included donor shortage, late referral to the transplant center and long donor or recipient work-up. Suggested initiatives included raising awareness on the possibility of preemptive kidney transplantation, earlier start and shorter work-up time for recipient and living donor. CONCLUSIONS: Over the last two decades the proportion of patients receiving a first kidney transplant preemptively has more than doubled, reflecting a similar relative increase for living and deceased donor kidney recipients.

A comparison of the epidemiology of kidney replacement therapy between Europe and the United States: 2021 data of the ERA Registry and the USRDS.

BACKGROUND AND HYPOTHESIS: This paper compares the most recent data on the incidence and prevalence of kidney replacement therapy (KRT), kidney transplantation rates, and mortality on KRT from Europe to those from the United States (US), including comparisons of treatment modalities (haemodialysis (HD), peritoneal dialysis (PD), and kidney transplantation (KTx)). METHODS: Data were derived from the annual reports of the European Renal Association (ERA) Registry and the United States Renal Data System (USRDS). The European data include information from national and regional renal registries providing the ERA Registry with individual patient data. Additional analyses were performed to present results for all participating European countries together. RESULTS: In 2021, the KRT incidence in the US (409.7 per million population (pmp)) was almost 3-fold higher than in Europe (144.4 pmp). Despite the substantial difference in KRT incidence, approximately the same proportion of patients initiated HD (Europe: 82%, US: 84%), PD (14%; 13% respectively), or underwent pre-emptive KTx (4%; 3% respectively). The KRT prevalence in the US (2436.1 pmp) was 2-fold higher than in Europe (1187.8 pmp). Within Europe, approximately half of all prevalent patients were living with a functioning graft (47%), while in the US, this was one third (32%). The number of kidney transplantations performed was almost twice as high in the US (77.0 pmp) compared to Europe (41.6 pmp). The mortality of patients receiving KRT was 1.6-fold higher in the US (157.3 per 1000 patient years) compared to Europe (98.7 per 1000 patient years). CONCLUSIONS: The US had a much higher KRT incidence, prevalence, and mortality compared to Europe, and despite a higher kidney transplantation rate, a lower proportion of prevalent patients with a functioning graft.

Factors influencing kidney transplantation rates: a study from the ERA Registry.

BACKGROUND: Large international differences exist in kidney transplantation (KT) rates. We aimed to investigate which factors may explain the total, deceased donor and living donor KT rates over the last decade. METHODS: KT experts from 39 European countries completed the Kidney Transplantation Rate Survey on measures and barriers and their potential effect on the KT rate in their country. In the analyses, countries were divided into low, middle and high KT rate countries based on the KT rate at the start of study period in 2010. RESULTS: Experts from low KT rate countries reported more frequently that they had taken measures regarding staff, equipment and facilities to increase the total KT rate compared with middle and high KT rate countries. For donor type-specific KT, the largest international differences in measures taken were reported for deceased donor KT, with middle and high KT rate countries taking more measures, such as the use of expanded criteria donor kidneys, the presence of transplantation coordinators and (inter)national exchange of donor kidneys. Once a measure was taken, experts' opinion on its success was similar across the low, middle and high KT rate countries. Experts from low KT rate countries more often reported potential barriers, such as patients' lack of knowledge and distrust in the healthcare system. CONCLUSIONS: Particularly in low KT rate countries, the KT rate might be stimulated by optimizing staff, equipment and facilities. In addition, all countries may benefit from measures specific to deceased and living donors.

Increasing numbers and improved overall survival of patients on kidney replacement therapy over the last decade in Europe: an ERA Registry study.

BACKGROUND: The aim of this study was to describe the trends in the incidence, prevalence and survival of patients on kidney replacement therapy (KRT) for end-stage kidney disease (ESKD) across Europe from 2008 to 2017. METHODS: Data from renal registries in 9 countries and 16 regions that provided individual patient data to the ERA Registry from 2008 to 2017 were included. These registries cover 34% of the general population in Europe. Crude and standardized incidence and prevalence per million population (pmp) were determined. Trends over time were studied using Joinpoint regression. Survival probabilities were estimated using Kaplan-Meier analysis and hazard ratios (HRs) using Cox regression analysis. RESULTS: The standardized incidence of KRT was stable [annual percentage change (APC): -1.48 (-3.15; 0.21)] from 2008 (146.0 pmp) to 2011 (141.6 pmp), followed by a slight increase [APC: 1.01 (0.43; 1.60)] to 148.0 pmp in 2017, although trends in incidence varied across countries. This increase was primarily due to a rise in the incidence of KRT in men older than 65 years. Moreover, as a cause of kidney failure, diabetes mellitus is increasing. The standardized prevalence increased from 2008 (990.0 pmp) to 2017 (1166.8 pmp) [APC: 1.82 (1.75; 1.89)]. Patient survival on KRT improved in the time period 2011-13 compared with 2008-[adjusted HR: 0.94 (0.93; 0.95)]. CONCLUSION: This study showed an overall increase in the incidence and prevalence of KRT for ESKD as well as an increase in the KRT patient survival over the last decade in Europe.

Trends in kidney transplantation rate across Europe: study from the ERA Registry.

BACKGROUND: The aim of this study was to identify trends in total, deceased donor (DD) and living donor (LD) kidney transplantation (KT) rates in European countries. METHODS: The European Renal Association (ERA) Registry and the Global Observatory on Donation and Transplantation (GODT) databases were used to obtain the number of KTs in individual European countries between 2010 and 2018. General population counts were obtained from Eurostat or the national bureaus of statistics. The KT rate per million population (p.m.p.) and the average annual percentage change (APC) were calculated. RESULTS: The total KT rate in the 40 participating countries increased with 1.9% annually  [95%  confidence  interval  (CI) 1.5, 2.2] from 29.6 p.m.p. in 2010 to 34.7 p.m.p. in 2018, reflecting an increase of 3.4 p.m.p. in the DD-KT rate (from 21.6 p.m.p. to 25.0 p.m.p.; APC 1.9%; 95% CI 1.3, 2.4) and of 1.5 p.m.p. in the LD-KT rate (from 8.1 p.m.p. to 9.6 p.m.p.; APC 1.6%; 95% CI 1.0, 2.3). The trends in KT rate varied widely across European countries. An East-West gradient was observed for DD-KT rate, with Western European countries performing more KTs. In addition, most countries performed fewer LD-KTs. In 2018, Spain had the highest DD-KT rate (64.6 p.m.p.) and Turkey the highest LD-KT rate (37.0 p.m.p.). CONCLUSIONS: The total KT rate increased due to a rise in the KT rate from DDs and to a lesser extent from LDs, with large differences between individual European countries.

Pregnancy after living kidney donation, a systematic review of the available evidence, and a review of the current guidance.

Understanding and communicating the risk of pregnancy complications post-living kidney donation is imperative as the majority of living kidney donors (LKD) are women of childbearing age. We aimed to identify all original research articles examining complications in post-donation pregnancies and compared the quality and consistency of related guidelines. We searched Embase, MEDLINE, PubMed, society webpages, and guideline registries for English-language publications published up until December 18, 2020. Ninety-three articles were screened from which 16 studies were identified, with a total of 1399 post-donation pregnancies. The outcome of interest, post-donation pregnancy complications, was not calculable, and only a narrative synthesis of the evidence was possible. The absolute risk of pre-eclampsia increased from ~1%-3% pre-donation (lower than the general population) to ~4%-10% post-donation (comparable to the general population). The risks of adverse fetal and neonatal outcomes were no different between post-donation and pre-donation pregnancies. Guidelines and consensus statements were consistent in stating the need to inform LKDs of their post-donation pregnancy risk, however, the depth and scope of this guidance were variable. While the absolute risk of pregnancy complications remains low post-donation, a concerted effort is required to better identify and individualize risk in these women, such that consent to donation is truly informed.

Incidence of Kidney Replacement Therapy and Subsequent Outcomes Among Patients With Systemic Lupus Erythematosus: Findings From the ERA Registry.

RATIONALE & OBJECTIVE: There is a dearth of data characterizing patients receiving kidney replacement therapy (KRT) for kidney failure due to systemic lupus erythematosus (SLE) and their clinical outcomes. The aim of this study was to describe trends in incidence and prevalence of KRT among these patients as well as to compare their outcomes versus those of patients treated with KRT for diseases other than SLE. STUDY DESIGN: Retrospective cohort study based on kidney registry data. SETTING & PARTICIPANTS: Patients recorded in 14 registries of patients receiving KRT that provided data to the European Renal Association Registry between 1992 and 2016. PREDICTOR: SLE as cause of kidney failure. OUTCOMES: Incidence and prevalence of KRT, patient survival while receiving KRT, patient and graft survival after kidney transplant, and specific causes of death. ANALYTICAL APPROACH: Kaplan-Meier methods and Cox regression models were fit to compare patient survival between the SLE and non-SLE groups, overall KRT, dialysis, and patient and graft survival after kidney transplant. RESULTS: In total, 1,826 patients commenced KRT for kidney failure due to SLE, representing an incidence of 0.80 per million population (pmp) per year. The incidence remained stable during the study period (annual percent change, 0.1% [95% CI, -0.6% to 0.8%]). Patient survival among patients with SLE receiving KRT was similar to survival in the comparator group (hazard ratio [HR], 1.11 [95% CI, 0.99-1.23]). After kidney transplant, the risk of death was greater among patients with SLE than among patients in the comparator group (HR, 1.25 [95% CI, 1.02-1.53]), whereas the risk of all-cause graft failure was similar (HR, 1.09 [95% CI, 0.95-1.27]). Ten-year patient overall survival during KRT and patient and graft survival after kidney transplant improved over the study period (HRs of 0.71 [95% CI, 0.56-0.91], 0.43 [95% CI, 0.27-0.69], and 0.60 [95% CI, 0.43-0.84], respectively). Patients with SLE receiving KRT were significantly more likely to die of infections (24.8%) than patients in the comparator group (16.9%; P < 0.001). LIMITATIONS: No data were available on extrarenal manifestations of SLE, drug treatments, comorbidities, kidney transplant characteristics, or relapses of SLE. CONCLUSIONS: The prognosis of patients with SLE receiving KRT has improved over time. Survival of patients with SLE who required KRT was similar compared with patients who required KRT for other causes of kidney failure. Survival following kidney transplants was worse among patients with SLE.

Patient-reported factors influencing the choice of their kidney replacement treatment modality.

BACKGROUND: Access to various kidney replacement therapy (KRT) modalities for patients with end-stage kidney disease differs substantially within Europe. METHODS: European adults on KRT filled out an online or paper-based survey about factors influencing and experiences with modality choice (e.g. information provision, decision-making and reasons for choice) between November 2017 and January 2019. We compared countries with low, middle and high gross domestic product (GDP). RESULTS: In total, 7820 patients [mean age 59 years, 56% male, 63% on centre haemodialysis (CHD)] from 38 countries participated. Twenty-five percent had received no information on the different modalities, and only 23% received information >12 months before KRT initiation. Patients were not informed about home haemodialysis (HHD) (42%) and comprehensive conservative management (33%). Besides nephrologists, nurses more frequently provided information in high-GDP countries, whereas physicians other than nephrologists did so in low-GDP countries. Patients from low-GDP countries reported later information provision, less information about other modalities than CHD and lower satisfaction with information. The majority of modality decisions were made involving both patient and nephrologist. Patients reported subjective (e.g. quality of life and fears) and objective reasons (e.g. costs and availability of treatments) for modality choice. Patients had good experiences with all modalities, but experiences were better for HHD and kidney transplantation and in middle- and high-GDP countries. CONCLUSION: Our results suggest European differences in patient-reported factors influencing KRT modality choice, possibly caused by disparities in availability of KRT modalities, different healthcare systems and varying patient preferences. Availability of home dialysis and kidney transplantation should be optimized.

Work status and work ability of patients receiving kidney replacement therapy: results from a European survey.

BACKGROUND: Employment is important for the quality of life and financial security of patients of working age receiving kidney replacement therapy (KRT). We aimed to examine self-reported work status and general, physical and mental work ability and to determine associations between demographic, disease-related, work-related and macroeconomic factors and employment. . METHODS: Europeans from 37 countries, ages 19-65 years, treated with dialysis or kidney transplantation, filled out the web-based or paper-based cross-sectional EDITH kidney patient survey between November 2017 and January 2019. We performed descriptive analyses and multivariable generalized logistic mixed models. RESULTS: Of the 3544 patients, 36.5% were employed and working [25.8% of dialysis patients, 53.9% of kidney transplant recipients (KTRs)]. The mean general work ability was 5.5 out of 10 (dialysis: 4.8, KTRs: 6.5). Non-working patients (all: 4.1, dialysis: 3.9, KTRs: 4.7) scored lower than working patients (all: 7.7, dialysis 7.3, KTRs: 8.0). Working dialysis patients scored lower on physical and mental work ability (7.1 and 8.1) than working KTRs (8.0 and 8.4; P < 0.001). Impaired physical work ability (42.7%) was more prevalent than impaired mental work ability (26.7%). Male sex, age 40-49 years, higher education, home dialysis or kidney transplantation as current treatment, treatment history including kidney transplantation, absence of diabetes mellitus, better general work ability and higher country gross domestic product were positively associated with employment (P < 0.05). CONCLUSIONS: Low employment rates and impaired work ability were prevalent among European patients receiving KRT. Demographic, disease-related, work-related and macro-economic factors were associated with employment.

Supplemented ERA-EDTA Registry data evaluated the frequency of dialysis, kidney transplantation, and comprehensive conservative management for patients with kidney failure in Europe.

The aims of this study were to determine the frequency of dialysis and kidney transplantation and to estimate the regularity of comprehensive conservative management (CCM) for patients with kidney failure in Europe. This study uses data from the ERA-EDTA Registry. Additionally, our study included supplemental data from Armenia, Germany, Hungary, Ireland, Kosovo, Luxembourg, Malta, Moldova, Montenegro, Slovenia and additional data from Israel, Italy, Slovakia using other information sources. Through an online survey, responding nephrologists estimated the frequency of CCM (i.e. planned holistic care instead of kidney replacement therapy) in 33 countries. In 2016, the overall incidence of replacement therapy for kidney failure was 132 per million population (pmp), varying from 29 (Ukraine) to 251 pmp (Greece). On 31 December 2016, the overall prevalence of kidney replacement therapy was 985 pmp, ranging from 188 (Ukraine) to 1906 pmp (Portugal). The prevalence of peritoneal dialysis (114 pmp) and home hemodialysis (28 pmp) was highest in Cyprus and Denmark respectively. The kidney transplantation rate was nearly zero in some countries and highest in Spain (64 pmp). In 28 countries with five or more responding nephrologists, the median percentage of candidates for kidney replacement therapy who were offered CCM in 2018 varied between none (Slovakia and Slovenia) and 20% (Finland) whereas the median prevalence of CCM varied between none (Slovenia) and 15% (Hungary). Thus, the substantial differences across Europe in the frequency of kidney replacement therapy and CCM indicate the need for improvement in access to various treatment options for patients with kidney failure.

Results of the European EDITH nephrologist survey on factors influencing treatment modality choice for end-stage kidney disease.

BACKGROUND: Access to forms of dialysis, kidney transplantation (Tx) and comprehensive conservative management (CCM) for patients with end-stage kidney disease (ESKD) varies across European countries. Attitudes of nephrologists, information provision and decision-making may influence this access and nephrologists may experience several barriers when providing treatments for ESKD. METHODS: We surveyed European nephrologists and kidney transplant surgeons treating adults with ESKD about factors influencing modality choice. Descriptive statistics were used to compare the opinions of professionals from European countries with low-, middle- and high-gross domestic product purchasing power parity (GDP PPP). RESULTS: In total, 681 professionals from 33 European countries participated. Respondents from all GDP categories indicated that ∼10% of patients received no information before the start of renal replacement therapy (RRT) (P = 0.106). Early information provision and more involvement of patients in decision-making were more frequently reported in middle- and high-GDP countries (P < 0.05). Professionals' attitudes towards several treatments became more positive with increasing GDP (P < 0.05). Uptake of in-centre haemodialysis was sufficient to 73% of respondents, but many wanted increased uptake of home dialysis, Tx and CCM. Respondents experienced different barriers according to availability of specific treatments in their centre. The occurrence of barriers (financial, staff shortage, lack of space/supplies and patient related) decreased with increasing GDP (P < 0.05). CONCLUSIONS: Differences in factors influencing modality choice when providing RRT or CCM to adults with ESKD were found among low-, middle- and high-GDP countries in Europe. Therefore a unique pan-European policy to improve access to treatments may be inefficient. Different policies for clusters of countries could be more useful.

Non-medical barriers reported by nephrologists when providing renal replacement therapy or comprehensive conservative management to end-stage kidney disease patients: a systematic review.

BACKGROUND: Large international differences exist in access to renal replacement therapy (RRT) modalities and comprehensive conservative management (CCM) for patients with end-stage kidney disease (ESKD), suggesting that some patients are not receiving the most appropriate treatment. Previous studies mainly focused on barriers reported by patients or medical barriers (e.g. comorbidities) reported by nephrologists. An overview of the non-medical barriers reported by nephrologists when providing the most appropriate form of RRT (other than conventional in-centre haemodialysis) or CCM is lacking. METHODS: We searched in EMBASE and PubMed for original articles with a cross-sectional design (surveys, interviews or focus groups) published between January 2010 and September 2018. We included studies in which nephrologists reported barriers when providing RRT or CCM to adult patients with ESKD. We used the barriers and facilitators survey by Peters et al. [Ruimte Voor Verandering? Knelpunten en Mogelijkheden Voor Verbeteringen in de Patiëntenzorg. Nijmegen: Afdeling Kwaliteit van zorg (WOK), 2003] as preliminary framework to create our own model and performed meta-ethnographic analysis of non-medical barriers in text, tables and figures. RESULTS: Of the 5973 articles screened, 16 articles were included using surveys (n = 10), interviews (n = 5) and focus groups (n = 1). We categorized the barriers into three levels: patient level (e.g. attitude, role perception, motivation, knowledge and socio-cultural background), level of the healthcare professional (e.g. fears and concerns, working style, communication skills) and level of the healthcare system (e.g. financial barriers, supportive staff and practice organization). CONCLUSIONS: Our systematic review has identified a number of modifiable, non-medical barriers that could be targeted by, for example, education and optimizing financing structure to improve access to RRT modalities and CCM.

Temporal trends in the quality of deceased donor kidneys and kidney transplant outcomes in Europe: an analysis by the ERA-EDTA Registry.

BACKGROUND: We investigated 10-year trends in deceased donor kidney quality expressed as the kidney donor risk index (KDRI) and subsequent effects on survival outcomes in a European transplant population. METHODS: Time trends in the crude and standardized KDRI between 2005 and 2015 by recipient age, sex, diabetic status and country were examined in 24 177 adult kidney transplant recipients in seven European countries. We determined 5-year patient and graft survival probabilities and the risk of death and graft loss by transplant cohort (Cohort 1: 2005-06, Cohort 2: 2007-08, Cohort 3: 2009-10) and KDRI quintile. RESULTS: The median crude KDRI increased by 1.3% annually, from 1.31 [interquartile range (IQR) 1.08-1.63] in 2005 to 1.47 (IQR 1.16-1.90) in 2015. This increase, i.e. lower kidney quality, was driven predominantly by increases in donor age, hypertension and donation after circulatory death. With time, the gap between the median standardized KDRI in the youngest (18-44 years) and oldest (>65 years) recipients widened. There was no difference in the median standardized KDRI by recipient sex. The median standardized KDRI was highest in Austria, the Netherlands and the Basque Country (Spain). Within each transplant cohort, the 5-year patient and graft survival probability were higher for the lowest KDRIs. There was no difference in the patient and graft survival outcomes across transplant cohorts, however, over time the survival probabilities for the highest KDRIs improved. CONCLUSIONS: The overall quality of deceased donor kidneys transplanted between 2005 and 2015 has decreased and varies between age groups and countries. Overall patient and graft outcomes remain unchanged.

Does kidney transplantation with a standard or expanded criteria donor improve patient survival? Results from a Belgian cohort.

BACKGROUND: Changes in recipient and donor factors have reopened the question of survival benefits of kidney transplantation versus dialysis. METHODS: We analysed survival among 3808 adult Belgian patients waitlisted for a first deceased donor kidney transplant from 2000 to 2012. The primary outcome was mortality during the median waiting time plus 3 years of follow-up after transplantation or with continued dialysis. Outcomes were analysed separately for standard criteria donor (SCD) and expanded criteria donor (ECD) kidney transplants. We adjusted survival analyses for recipient age (20-44, 45-64 and ≥65 years), sex and diabetes as the primary renal disease. RESULTS: Among patients ≥65 years of age, only SCD transplantation provided a significant survival benefit compared with dialysis, with a mortality of 16.3% [95% confidence interval (CI) 13.2-19.9] with SCD transplantation, 20.5% (95% CI 16.1-24.6) with ECD transplantation and 24.6% (95% CI 19.4-29.5) with continued dialysis. Relative mortality risk was increased in the first months after transplantation compared with dialysis, with equivalent risk levels reached earlier with SCD than ECD transplantation in all age groups. CONCLUSIONS: The results of this study suggest that older patients might gain a survival benefit with SCD transplantation versus dialysis, but any survival benefit with ECD transplantation versus dialysis may be small.

Transplantation outcomes in patients with primary hyperoxaluria: a systematic review.

BACKGROUND: Primary hyperoxaluria type 1 (PH1) is characterized by hepatic overproduction of oxalate and often results in kidney failure. Liver-kidney transplantation is recommended, either combined (CLKT) or sequentially performed (SLKT). The merits of SLKT and the place of an isolated kidney transplant (KT) in selected patients are unsettled. We systematically reviewed the literature focusing on patient and graft survival rates in relation to the chosen transplant strategy. METHODS: We searched MEDLINE and Embase using a broad search string, consisting of the terms 'transplantation' and 'hyperoxaluria'. Studies reporting on at least four transplanted patients were selected for quality assessment and data extraction. RESULTS: We found 51 observational studies from 1975 to 2020, covering 756 CLKT, 405 KT and 89 SLKT, and 51 pre-emptive liver transplantations (PLT). Meta-analysis was impossible due to reported survival probabilities with varying follow-up. Two individual high-quality studies showed an evident kidney graft survival advantage for CLKT versus KT (87% vs. 14% at 15 years, p<0.05) with adjusted HR for graft failure of 0.14 (95% confidence interval: 0.05-0.41), while patient survival was similar. Three other high-quality studies reported 5-year kidney graft survival rates of 48-89% for CLKT and 14-45% for KT. PLT and SLKT yielded 1-year patient and graft survival rates up to 100% in small cohorts. CONCLUSIONS: Our study suggests that CLKT leads to superior kidney graft survival compared to KT. However, evidence for merits of SLKT or for KT in pyridoxine-responsive patients was scarce, which warrants further studies, ideally using data from a large international registry.

Points of attention when conducting etiological research.

Epidemiological studies often aim to investigate the causal contribution of a risk factor to a disease or other outcome. In etiological research, one is usually interested in the (biological) mechanism(s) underlying the studied relationship. Inappropriate conduct of an etiological study may have major implications for the correctness of the results and interpretation of the findings. Therefore, in this paper, we aim to describe step by step how etiological research should be carried out, together with its  common pitfalls. These steps involve finding and formulating a well-defined etiological research question, choosing an appropriate study design including a suitable comparison group, adequate modelling, and adequate reporting and interpretation of the results.

Be careful with ecological associations.

Ecological studies are observational studies commonly used in public health research. The main characteristic of this study design is that the statistical analysis is based on pooled (i.e., aggregated) rather than on individual data. Thus, patient-level information such as age, gender, income and disease condition are not considered as individual characteristics but as mean values or frequencies, calculated at country or community level. Ecological studies can be used to compare the aggregated prevalence and incidence data of a given condition across different geographical areas, to assess time-related trends of the frequency of a pre-defined disease/condition, to identify factors explaining changes in health indicators over time in specific populations, to discriminate genetic from environmental causes of geographical variation in disease, or to investigate the relationship between a population-level exposure and a specific disease or condition. The major pitfall in ecological studies is the ecological fallacy, a bias which occurs when conclusions about individuals are erroneously deduced from results about the group to which those individuals belong. In this paper, by using a series of examples, we provide a general explanation of the ecological studies and provide some useful elements to recognize or suspect ecological fallacy in this type of studies.