Chronic kidney disease (CKD) will be the second leading cause of death worldwide by the year 21001 and the third in Spain by 2050.2 The Spanish Registry of Dialysis and Transplantation (REDYT) is an essential data source for understanding the incidence, prevalence and mortality of patients on kidney replacement therapy (KRT) in Spain. REDYT is the result of a collaborative effort among the Kidney Disease Registries of the Autonomous Communities (AC) and autonomous cities, the Spanish Society of Nephrology (S.E.N.) and the Organización Nacional de Trasplantes (ONT), which is responsible for data management and analysis. In addition to collaborating with the European Renal Association (ERA) and the United States Renal Data System (USRDS) registry, the REDYT report (formerly known as REER) has been presented at the annual S.E.N. congress since 1996, and last year published the data corresponding to the 2022 Report.3

Despite advances in diagnostic and therapeutic tools, CKD remains among the most underdiagnosed diseases with the worst prognosis. In population terms, Spain ranks among the top European countries in CKD prevalence and only slightly below the United States of America.3–5

The objective of this report is to update and describe the prevalence, incidence and mortality data of patients on KRT in Spain for the year 2023, comparing the trends over recent years.

The REDYT report for 2023 shows that KRT incidence in Spain is at the highest point in the entire historical series since 2006 (153.7 pmp). Likewise, kidney transplant activity has reached 76.8 pmp, maintaining Spain as a world leader in this KRT modality. Regarding mortality, it stands at 7.4%, the lowest in the last 4 years, a finding that should undoubtedly be contextualized within the COVID-19 pandemic.8

Despite the growing interest in slowing CKD and reducing the need for KRT in Spain, REDYT data do not yet show any benefit in terms of prognosis, although it is true that many therapeutic advances may be too recent. If this trend continues, CKD will be the third leading cause of death in Spain, behind only Alzheimer's disease and chronic obstructive pulmonary disease.2 The causes explaining this situation are several and demand profound reflection by the nephrology community. In recent years, we have witnessed the approval of drugs such as sodium-glucose cotransporter 2 inhibitors (SGLT2i),9–11 glucagon-like peptide-1 receptor agonists (GLP-1 RA)12 and nonsteroidal mineralocorticoid receptor antagonists (nonsteroidal MRA).13 These drugs, with extensive cardiorenal benefits in patients with CKD, have not yet achieved the desired penetrance in Spain, resulting in a significant percentage of patients receiving suboptimal treatment.14

Likewise, the importance of implementing therapeutic measures has as its determining factor the early diagnosis of CKD itself. While it is true that creatinine and estimated glomerular filtration rate (eGFR) are routinely ordered in clinical practice, albuminuria remains a parameter that goes unnoticed by most specialists.15 It should be noted that albuminuria is itself a risk factor for the development of cardiovascular events, so its early detection, even with normal eGFR, allows interventions to slow CKD progression and improve cardiovascular prognosis.16,17 In fact, the most determining factor for the beneficial effect of pharmacological treatment is its early initiation.18 Added to this is the systematic exclusion of patients with advanced CKD stages from clinical trials, which imposes significant limitations on the approval of novel drugs in these patients.19

Regarding CKD etiology, diabetes persists as the leading cause of KRT initiation in Spain, with the highest figure in the entire historical series, increasing from 21.8% (25.6 pmp) in 2022 to 25.2% (33.9 pmp) in 2023.3 This finding is surprising given that most drugs developed in the last decade have focused precisely on this type of renal involvement. While it is true that the impact on progression may take years to generate a clinical impact, it is concerning that diabetes continues to grow year after year. It is important to mention the change in CKD etiology classification adopted in REDYT in 2022 to align with that used by the ERA, although diabetes has always been classified as such throughout the series. On the other hand, the classification of diabetes as a comorbidity of a patient probably leads to it being established as the primary CKD etiology without considering alternatives. In this regard, some studies have shown that up to 40% of patients with diabetes may have an alternative diagnosis that should be considered for the management of the primary condition.20 Furthermore, the implementation of new strategies, such as genetic testing, is enabling more precise identification of CKD etiology, reducing the percentage of patients with miscellaneous etiology (which includes CKD of unknown origin and remains the second most frequent cause at 20.9% of cases).21,22

In the case of dialysis, HD remains the predominant modality in terms of incidence, although in recent years it has shown a slow decline in selection; conversely, PD reaches its peak incidence in this report at 25.9 pmp. Home HD is the least chosen modality, with its geographic distribution being a challenge to be considered.23

Kidney transplantation places Spain as a world leader in this field with a rate of 76.8 pmp (7% more than in 2022),3 well above the European average (38.0 pmp) and the global average (16.7 pmp). Although brain death donation persists as the primary organ source, donation after circulatory death has advanced significantly over the last decade, approaching the former.24 In this latest report, the considerable increase in living donation in Spain stands out, reaching an all-time high of 435 transplants (24.3% more than in 2022).3 Although the trend in recent years demonstrates consistency in this increase, efforts should be directed toward achieving higher rates in order to reduce the waiting list and the prognostic consequences of delayed graft reception. However, large differences persist between communities in the percentage of KRT patients with a functioning kidney graft or in access to different donation modalities. It would be necessary to evaluate the reasons for these differences to correct aspects that may compromise healthcare system equity.

Mortality in patients on KRT has remained stable during the last decade at approximately 7.5% (similar to ERA data),25 except for the 2020–2022 period in which mortality in these patients reached 8.4% as a consequence of the COVID-19 pandemic. It is good news that annual mortality of transplant recipients has returned to pre-pandemic levels, as in 2022 it was still 62% higher. The suboptimal response to vaccines and to primary infection may have played a role.26,27 However, the secular stagnation of mortality is not an optimal result. This finding is explained by the absence of innovation (both pharmacological and technical) in patients requiring KRT, especially those on HD and PD.28 Although the prescription of certain prognostic drugs (such as SGLT2i or GLP-1 RA) is beginning to become widespread in patients on KRT, these patients continue to be excluded from clinical trials.29,30 Added to this, the immunosuppression of transplantation or the fact that KRT techniques have barely changed over the last decade, a situation on which we must focus to try to improve patient prognosis. Likewise, improving transplant outcomes is associated with better vital prognosis since, as shown in Table 7, patients who do not receive a transplant have an almost 8-fold higher risk of death.

The present study has limitations. First, its design as an epidemiological registry limits the number of variables collected in order to achieve greater data completion. Second, the coding of etiology has changed throughout the historical series, making this variable difficult to compare. Third, although REDYT is a mandatory registry, some data are incomplete due to changes within some regional registries or lack of commitment from some centers. Despite this, since REDYT receives data from more than 95% of the territory, we may assume these losses without substantially modifying the results. Lastly, causes of mortality do not have a homogeneous definition and are not always evident, so some patients may have been classified incorrectly.

Data from the REDYT 2023 Report show increasing incidence and prevalence of persons requiring KRT in Spain, with differences in terms of sex and among the different AC. Diabetes mellitus remains the most frequent cause of KRT initiation. Kidney transplant activity in Spain is at all-time highs, with brain death and donation after circulatory death being the most common modalities and a significant increase in living donation. Mortality of patients on KRT has returned to a path of stability after increasing during the COVID-19 pandemic years and thereafter, with age, KRT modality, sex and diabetes being the independent predictors. The large differences between communities in the relative prevalence of transplantation and dialysis and in access to all donation modalities suggest that the equity of the national health system needs to be reassessed. It is also necessary to reverse the growing trend in KRT need by implementing active prevention and early CKD diagnosis policies, following the recommendations of the 2025 World Health Organization Declaration on kidney health, which was supported by Spain.31–33 The inclusion of CKD in the Strategy for Addressing Chronicity in the National Health System represents an advance in this field.34

BQ's research is funded by Instituto de Salud Carlos III (ISCIII) FIS/Fondos FEDER RICORS program to RICORS2040 (RD21/0005/0028) funded by European Union – NextGenerationEU, Mecanismo para la Recuperación y la Resiliencia (MRR) and PI25/00413. MM's research is funded by Instituto de Salud Carlos III (ISCIII) FIS PI23/01518. AO's research is funded by Comunidad de Madrid en BiomedicinaP2022/BMD-7223, CIFRA_COR-CM. Instituto de Salud Carlos III (ISCIII), (PI22/00469, PI22/00050, PI21/00251), ERA-PerMed-JTC2022 (SPAREKID AC22/00027), RICORS program to RICORS2040-renal (RD21/0005/0001, RD24/0004/0001) co-funded by European Union and SPACKDcPMP21/00109, FEDER funds; COST Action PERMEDIKCA21165 supported by COST (European Cooperation in Science and Technology); PREVENTCKD Consortium Project ID 101101220 Programme EU4H DG/Agency HADEA; KitNewCare Project ID 101137054, Call HORIZON-HLTH-2023-CARE-04, Programme HORIZON, DG/Agency HADEA; PICKED Project ID 101168626 HORIZON-MSCA-2023-DN-01-01 MSCA Doctoral Networks 2023. DHM's research is partly funded by Instituto de Salud Carlos III (ISCIII) FIS/Fondos FEDER, RICORS program to RICORS2040 (RD24/0004/0025) funded by European Union – NextGenerationEU, Ministerio de Economia e Innovación (ICI21/00042) and Fundación Instituto de Investigación Sanitaria de Canarias (FIISC) PIFIISC23/12.