Pathways to Equitable Access to Kidney Transplantation in Spain (PATH2KT): A Transformative Mixed-methods Study Protocol
Conditions: Chronic Kidney Disease, Kidney Transplant
Sponsor: Hospital del Mar

Pathways to equitable access to kidney transplantation in 
Spain (PATH2KT): A transformative mixed-methods study 
protocol  
 
Guillermo PEDREIRA-ROBLES 1,2,† , Montserrat SANCLEMENTE-DALMAU 
1,2, Laura ROTA-MUSOLL 3, Maria SÀEZ-SOL 2, Carlos VILCHES 4,*, Esther 
INSA-CALDERÓN 1,2,*, Beatriz DOMÍNGUEZ-GIL 4,* , on behalf of the PATH2KT 
research group** 
 
1 Hospital del Mar Nursing School (ESIHMar), Universitat Pompeu Fabra-affiliated, 
Barcelona, Spain 
2 Social Determinants and Health Education Research Group (SDHEd), Hospital del 
Mar Research Institute 
3 Research group on Methodology, Methods, Models and Outcomes of Health and 
Social Sciences (M3O), Faculty of Health Sciences and Welfare, Centre for Health 
and Social Care Research (CESS), University of Vic-Central University of Catalonia 
(UVic-UCC), Vic, Barcelona, Spain. 
4 Organización Nacional de Trasplantes, Madrid, Spain. 
 
* These authors contributed equally, as senior authors. 
 
** The PATH2KT research group includes the following members, listed in alphabetical 
order: Jesús ALCOBER, president of the ADER Foundation (Kidney Patients 
Association of Catalonia); Maria Eva BARÓ-SALVADOR, Country Medical 
Director Spain at Fresenius Medical Care; Maria Dolores ARENAS, Managing 
Director at Fundación Renal; Itziar BUENO-ZAMARBIDE, president of the Spanish 
Society of Nephrology Nursing; José Luis COBO-SÁNCHEZ, Research Board 
Member of the Spanish Society of Nephrology Nursing; Daniel GALLEGO-
ZURRO, president of the National Federation of Associations for the Fight Against 
Kidney Diseases; David HERNÁN-GASCUEÑA, Director of Nursing at Fundación 
Renal; Irene LARRAÑETA-INDA, vice president of the Spanish Society of 
Nephrology Nursing; Sandra MAESTRE-LERGA, treasurer of the Spanish Society 
of Nephrology Nursing; Shaira MARTÍNEZ,  Auxiliadora MAZUECOS, board 
member for kidney transplantation of the Spanish Society of Nephrology; María José 
PÉREZ-SÁEZ, secretary of the Kidney Transplant Working Group of the Spanish 
Society of Nephrology; Ignacio REVUELTA, coordinator of the Kidney Transplant 
Working Group of the Spanish Society of Nephrology; Emilio SÁNCHEZ-
ÁLVAREZ, president of the Spanish Society of Nephrology; Maria Paz 
SORRIBES-LÓPEZ, Director of Nursing at Diaverum; Ana ULZURRUN-
GARCÍA, secretary general of the Spanish Society of Nephrology Nursing. 
 
† Correspondence: Guillermo Pedreira Robles. Hospital del Mar Nursing School. Doctor 
Aiguader 80, 3ª planta 08003 Barcelona. gpedreira@hmar.cat 
 
 
ORCID - GPR: 0000-0002-6180-4059; MSD 0000-0003-1518-4976; LRM 0000-0001-
8351-0476; MSS 0009-0001-2406-7141; CV; EIC 0000-0003-4778-9769; BDG 0000-
0002-5695-8993. 
 

Abstract 
Introduction. Chronic kidney disease (CKD) affects 10%–15% of the global population 
and is projected to become the fifth leading cause of years of life lost by 2040. Despite 
the benefits of kidney transplantation (KT), access remains inequitable. In Spain, which 
leads the world in KT rates per million population, disparities may persist due to 
structural, territorial, and professional barriers. This study aims to explore the 
mechanisms underlying treatment deprivation and inequity in KT access using a mixed-
methods approach. 
Methods and analysis. A transformative mixed-methods design will be implemented in 
four phases: (1) systematic reviews on instruments assessing treatment deprivation and 
inequalities in CKD and KT; (2) a multicentre quantitative study and qualitative 
interviews with professionals and patients; (3) a pre-experimental evaluation of a training 
program on KT; and (4) triangulation and translation of findings to inform national policy. 
The protocol adheres to GRAMMS and PRISMA guidelines. 
Ethics and dissemination. Approved by the Hospital del Mar Research Institute Ethics 
Committee (ID: 2025/12128/I), the study complies with EU data protection laws. 
Informed consent will be obtained. Findings will be disseminated via peer-reviewed 
publications, conferences, social media, and patient forums to support equity-focused 
strategies in KT. 
Registration and financial details. Registered on ClinicalTrials.gov (ID: XX); 
systematic reviews registered in PROSPERO. Funded by the Spanish Organización 
Nacional de Trasplantes (€74,597.49), with additional funding to be sought. Funders will 
not influence any part of the research process. 
 
Keywords. Kidney transplantation; chronic kidney disease; Health equity; Treatment 
deprivation; Access to care; Social determinants of health; Mixed-methods research; 
Transformative paradigm 
 
 

Strengths and limitations of this study 
● This is the first national study in Spain to examine treatment deprivation and 
access inequities to KT using a transformative mixed-methods design. 
● It includes both professional and patient perspectives to understand the underlying 
mechanisms of inequity. 
● The study will generate actionable evidence to inform national strategies, 
including the ATRAE initiative. 
● The multicenter design enhances generalizability but may introduce variability in 
data collection processes. 
● Although the study focuses on the Spanish context, findings may be applicable to 
other decentralized health systems facing similar challenges. 
 
 
 
 
 
 
 
 
 
 

INTRODUCTION 
It is estimated that between 10% and 15% of the global population, approximately 850 
million people, have some degree of chronic kidney disease (CKD), based on a global 
population of approximately 8.06 billion and recent estimates from the literature 1–3. This 
figure is expected to rise, with 5.4 million people projected to undergo some form of renal 
replacement therapy (RRT) by 2030 4. Furthermore, CKD is expected to become the fifth 
leading cause of years of life lost worldwide by 2040 5. In light of these trends, it is also 
well-known that not all individuals who require RRT have access to it, and between 2.3 
and 7.1 million adults die prematurely due to lack of access 6. This situation should serve 
as a wake-up call for the international health community, who must firmly commit to 
implementing measures and equitable pathways across the global population, while also 
adopting preventive strategies to reverse the anticipated burden of disease in less than 10–
20 years. 
Among all RRT modalities, kidney transplantation (KT) offers the greatest benefits in 
terms of survival, complications, quality of life, and economic costs, making it the 
treatment of choice for this population 7–9. However, access to KT remains limited, as it 
is available only to a portion of the global population 10,11. As of the most recent data, KT 
activities were reported by 91 of the 193 countries worldwide, indicating that less than 
half of all countries currently provide or, at least, report this service 12. This highlights 
persistent global disparities in access to transplantation. Barriers to treatment are 
influenced not only by a country's income level or healthcare infrastructure, but also by 
broader structural, geographic, and systemic challenges that go beyond the 
socioeconomic profile of a territory or its gross domestic product 11. 
Several studies have been published internationally, analyzing barriers to equitable 
access to KT. These studies describe factors such as race, gender, age, religion, 
comorbidities or accompanying disabilities, socioeconomic and educational level, place 
of residence, geographic distribution of health services, personal and professional 
characteristics of healthcare teams, staffing at reference centers, legislation, presence of 
other economic interests or preferences, and more, which significantly influence access –
or lack thereof– to KT 7,10,13–18. In the Spanish context, although universal healthcare 
coverage is in place, inequalities in access to KT might exist across different regions and 
patient profiles. These analyses are challenging to interpret collectively, due to the vast 

number of individual determinants to consider and the discrepancies observed between 
studies, which are not always aligned 10,14. 
Given these challenges, over the past few decades, deprivation indices have been 
increasingly used under a health and evaluation framework in assessing access to 
healthcare. Deprivation indices are tools that quantify social, economic, and geographical 
inequalities limiting access to healthcare 19. In the context of CKD, the preliminary use of 
these indices has shown that social deprivation is linked to a lower likelihood of receiving 
preventive KT or living donor transplants, worse clinical outcomes, and higher mortality 
rates 20–23. In Spain, there is a lack of studies addressing how social and territorial 
inequalities impact access to KT, as well as a lack of comprehensive analyses exploring 
how personal, structural, and systemic variables interact to shape access to or deprivation 
from KT. 
Focusing more specifically on the Spanish case, CKD affects an estimated 15% of the 
adult population, corresponding to approximately seven million people 24. However, less 
than 1% progress to advanced stages of CKD requiring RRT, with around 65,000 
individuals currently receiving dialysis or living with a functioning KT 25. Among these, 
approximately 55% have received a transplant, underscoring Spain’s internationally 
recognized leadership in KT activity. Nevertheless, a proportion of eligible patients may 
not ultimately access this treatment. As observed internationally, a local study in Southern 
Spain revealed that only a fraction of patients with advanced CKD are ultimately 
evaluated for KT, despite being the treatment with the most favorable outcomes at both 
personal and systemic levels 17. In this regard, it is important to highlight that research on 
access to KT in Spain remains limited, and key hypotheses have yet to be empirically 
tested. 
Building on this gap, the present study protocol is based on the hypothesis that 
treatment deprivation and inequities in access to KT may not be randomly distributed, but 
may result from the interaction of systemic, social, and professional factors embedded at 
different levels of the healthcare system. In line with this assumption, the protocol aims 
to explore the potential factors that may contribute to inequity and treatment deprivation 
among individuals with CKD in relation to KT access. Focusing exclusively on the 
Spanish healthcare system and sociopolitical context, it also seeks to examine how such 
factors may be structurally embedded in society and to explore the perspectives of 
professionals working in this field, with the aim of identifying possible areas for 

improvement. Upon completion of the different stages of this protocol, we aim to outline 
a framework that could offer applicable responses for healthcare management systems, 
which may help inform the implementation of corrective measures to promote more 
equitable and high-quality care. 
Objectives 
This project is divided into six specific objectives, which will be addressed in parallel to 
provide answers and, in the end, construct a unified meaning with all integrated parts: 
1. To synthesize and critically appraise the literature on instruments and variables 
used to evaluate inequities among individuals with CKD. 
2. To explore how unequal access to KT is portrayed and explained in the scientific 
literature. 
3. Analyze possible inequities of access to KT in the CKD population in Spain, using 
a quantitative approach.  
4. Explore the experiences of healthcare managers in Spain at the micro, meso and 
macro levels, as well as the experiences of patients, regarding health inequalities 
and access to KT, using a qualitative approach. 
5. Evaluate the impact of a training course on living donor KT in Spain on the 
knowledge, attitudes, and practices of nurses and physicians by comparing 
indicators before and after the training. 
6. Triangulate and translate the study’s findings into actionable evidence to inform 
the national strategy for equitable access to KT in Spain, particularly by 
supporting the development of consensus recommendations within the ATRAE 
initiative. 
METHODS AND ANALYSIS 
Study design 
The design of this research protocol follows the premises of the mixed-methods approach 
under the transformative paradigm 26,27. This means that various phases of data collection 
–both quantitative and qualitative– will be conducted, analyzed separately, and then 
integrated through methodological triangulation to corroborate and enrich the findings 28. 
The research will be centered on social justice, amplifying the voices of communities 
facing health inequalities or treatment deprivation. Using the transformative mixed-
methods approach, different power structures that may be involved in the results will be 

analyzed and linked to actions that promote equity, ultimately providing a report with 
recommendations for action based on the results obtained 26,27. The achievement of results 
under this methodology and paradigm will be accomplished through various research 
phases, explained in detail below. 
This protocol follows the Good Reporting of A Mixed Methods Study (GRAMMS) 
guidelines, recognized for ensuring high-quality evidence-based methodology 29. 
Patient and public involvement 
This protocol has been reviewed and endorsed by the CKD community in Spain, 
including the National Federation of Associations for the Fight Against Kidney Diseases 
(ALCER) and the ADER Foundation (Kidney Patients Association of Catalonia). These 
organizations will actively support the dissemination of the study in different regions and 
will facilitate recruitment of participants during the data collection phase. Moreover, 
patient representatives will be involved in the interpretation of findings, ensuring that the 
analysis incorporates lived experiences and enhances the relevance and clarity of results. 
Study setting and context 
The data collection components of this research protocol will be conducted in Spain, a 
high-interest setting for the care of people with CKD. Spain's healthcare system is public 
and universal, primarily funded through taxes, ensuring healthcare access for the entire 
population, including individuals requiring KT 30. The country is internationally 
recognized for its high rates of organ donation and transplantation, supported by the 
Spanish National Transplant Organization (Organización Nacional de Trasplantes, ONT), 
which emphasizes coordination, regulation, and public engagement 31. Spain’s healthcare 
system is also highly decentralized, with responsibilities for healthcare planning, service 
delivery, and resource allocation delegated to the 17 autonomous regions. This structure 
includes regional transplant coordination offices that work in alignment with the ONT to 
implement national policies at the local level, but may also reflect regional specificities 
and priorities. Despite this strong institutional framework, inequities in KT access might 
arise from factors such as socioeconomic status, geographic area and interregional 
differences linked to the decentralized organization of the healthcare system. By focusing 
solely on the Spanish context, while allowing for international discussion across the 
proposed phases, this study seeks to generate detailed insights and propose actionable 

recommendations grounded in the realities of Spain's healthcare infrastructure and 
sociopolitical landscape. 
Data collection and analysis 
Data collection and analysis will be carried out using a mixed approach, combining both 
quantitative and qualitative methods. This will result in four distinct research phases, 
tailored to the specific objectives of this research protocol. 
Phase 1. Literature review 
The first phase of this study aims to address objectives 1 and 2, which focus on 
synthesizing and critically appraising the existing literature on instruments and variables 
used to evaluate inequities among individuals with CKD, as well as on examining how 
unequal access to KT is described and explained. To achieve this, two systematic reviews 
will be conducted. 
Both reviews will be carried out following the methodological recommendations of 
the Joanna Briggs Institute (JBI) and will be reported according to the PRISMA 2020 
guidelines 32,33. The protocols for the reviews will be registered in PROSPERO®. Searches 
will be conducted in the major electronic databases, using controlled vocabulary (MeSH) 
and will include peer-reviewed studies published between 2015 and 2025 in English, 
Spanish, French, or Portuguese. Eligibility criteria will be based on the PICOT 
framework, and include quantitative, qualitative, and mixed-methods research, as well as 
systematic and scoping reviews. Study selection, data extraction, and critical appraisal 
will be carried out independently by two or more reviewers, with discrepancies resolved 
by consensus or consultation with a third reviewer. Covidence® software will be used to 
manage the workflow. 
Given the expected methodological heterogeneity, results will be synthesized 
narratively and organized thematically, according to the domains assessed, levels of 
analysis, validation approaches, and applicability of the instruments in both clinical and 
research contexts. These findings will provide a foundational knowledge base for the 
subsequent phases of the study. 
 
 

Phase 2. Inequities analysis 
This phase addresses objectives 3 and 4 by examining inequities in access to KT 
among individuals with CKD.  
For the quantitative component (objective 3), a descriptive study will be conducted 
across Spain using a snowball sampling strategy through healthcare networks and patient 
organizations to ensure representativeness and inclusivity. Recruitment will continue 
until data saturation is reached, with a minimum of 500 participants to guarantee diversity 
across sociodemographic groups. Data will be collected through the questionnaires 
developed in Phase 1, complemented with sociodemographic and clinical variables to 
provide a comprehensive understanding of participants’ health status and backgrounds. 
A multi-channel strategy will be applied to facilitate recruitment, involving healthcare 
professionals at nephrology and transplant centers, national and regional patient 
associations such as ALCER and ADER, and an online standardized interest form 
disseminated through institutional and collaborative networks, including ONT, SEDEN, 
and SEN. All participants will receive an information sheet and will be able to contact the 
research team directly to confirm their participation. No clinical information will be 
accessed without explicit consent, and contact details will only be shared if the participant 
initiates communication. This decentralized approach ensures voluntary participation and 
strict compliance with ethical standards in research involving potentially vulnerable 
populations. Statistical analysis will be carried out using SPSS® software. Descriptive 
statistics, including means, medians, standard deviations, and frequencies, will be used to 
summarize the sample characteristics, while inferential analyses such as t-tests, Wilcoxon 
tests, chi-square tests, and regression models will be applied depending on the type and 
distribution of the data. Assumptions for parametric tests will be verified, with non-
parametric alternatives used when appropriate. Missing data will be managed through 
multiple imputation or complete-case analysis, depending on the extent and pattern of 
missingness, in order to ensure the robustness and validity of the findings. 
For the qualitative component (objective 4), a descriptive study with a 
phenomenological orientation will be conducted to explore and understand in depth the 
experiences, perceptions, and meanings attributed to treatment deprivation by both 
healthcare professionals and individuals living with CKD. This approach will enable the 
identification of common patterns and differences between perspectives, providing a 
comprehensive view of the phenomenon from both sides of the healthcare relationship. 

Data will be collected through semi-structured, in-depth interviews guided by open-
ended, non-directive questions designed to foster a fluid dialogue between interviewer 
and participant. Two main groups of participants will be included: healthcare 
professionals involved in CKD care and KT, and patients with direct experience in the 
transplant process, including evaluation, waiting list, or transplantation. Healthcare 
professionals must have at least two years of experience in nephrology, transplant 
coordination, or related fields. Participants will be selected using purposive sampling with 
maximum variation to ensure diversity in roles, stages of CKD, and geographic regions. 
Interviews will be conducted by trained researchers or research assistants experienced in 
qualitative interviewing and working with vulnerable populations. Sessions will take 
place either in private spaces at participating healthcare centers (e.g., hospitals, transplant 
units, nursing schools) or through secure video calls, according to participants’ 
preferences and availability, ensuring accessibility. Each interview is expected to last 
between 45 and 60 minutes, will be audio-recorded with prior consent, and subsequently 
transcribed verbatim for analysis. Follow-up interviews will be scheduled if necessary. 
Recruitment will continue until theoretical saturation is reached, defined as the point 
where no new themes or categories emerge from additional data 34. Data will be analyzed 
inductively using a thematic approach and content analysis to identify and categorize 
recurring patterns, with successive steps of coding, grouping into categories, and 
synthesizing into central themes. To ensure credibility and rigor, strategies such as 
investigator triangulation, participant validation, and reflective journaling of analytical 
decisions will be applied 35. All data will be anonymized using unique codes, stored 
securely, and handled in compliance with ethical standards. Atlas.ti software will be used 
to support the analytic process. 
Upon completing this second research phase, we will have detailed data on inequities 
in access to KT in the Spanish context, together with the meanings attributed to this 
phenomenon by both the professional community and patients, providing comprehensive 
insights to inform the subsequent phases of the study. 
Phase 3. Impact of training 
In this third phase, objective 5 will be addressed by evaluating the impact of a training 
course in Spain on living donor KT for healthcare professionals. This particular course 
has been selected due to its established relevance within the Spanish context and potential 

impact upon access to KT: it has already completed three successful editions and has 
gained national recognition as one of the most important and well-regarded training 
programs on KT in Spain. Notably, the course is aimed at professionals working in non-
transplant centers, particularly dialysis units and advanced CKD clinics, which positions 
it to directly influence early referral pathways and improve access to KT. Its consolidated 
presence and perceived influence on clinical practice make it a strategic candidate for 
evaluation. 
A preexperimental quantitative study will be conducted with a pretest-posttest design. 
The study population will consist of healthcare professionals participating in the training, 
selected through convenience sampling. Data collection will be carried out through a 
structured questionnaire that will measure participants' knowledge, attitudes, and 
practices before, after, and one year after the course. The questionnaire will include 
multiple-choice questions to assess knowledge, Likert scales to analyze attitudes, and 
questions about behaviors and clinical decision-making regarding living donor KT. The 
instrument's validity and reliability will be verified through prior piloting and consensus 
among the research team. Data analysis will involve descriptive statistics to characterize 
the sample and compare pre- and post-intervention results. Statistical tests such as the 
paired t-test or the Wilcoxon test, depending on the data distribution, will be applied to 
determine whether significant differences exist after training. Additionally, effect size 
measures, such as Cohen's d for continuous variables and Cramer's V for categorical 
variables, will be calculated to quantify the impact of the course on the evaluated 
variables. 
The results obtained will help identify the effectiveness of the course in improving 
healthcare professionals' knowledge and perceptions about living donor KT, which can 
serve as the basis for future training strategies and for optimizing equitable access to KT 
within Spain. 
Phase 4. Integration of findings and contribution to the ATRAE national plan 
In the fourth and final phase of the project, the results obtained in the previous stages 
will be triangulated and synthesized to generate comprehensive, evidence-based 
knowledge (objective 6). This phase is conceived as an integrative component that will 
enable the transfer of research findings into actionable recommendations, directly 
contributing to the development of the national strategy for improving access to KT in 

Spain. The synthesis will support the creation of a consensus document within the 
ATRAE project: Optimizing Access to Kidney Transplantation in Spain. ATRAE is a 
national initiative led by the ONT, the Transplant Commission of the Interterritorial 
Council of the Spanish National Health System (CIT-SNS), and the Spanish Society of 
Nephrology (SEN), in collaboration with the Spanish Association of Urology (AEU), the 
Spanish Society of Nephrology Nursing (SEDEN), the Spanish Society of Immunology 
(SEI), and the Spanish Transplant Society (SET), and with the participation of the 
National Federation of Associations for the Fight Against Kidney Diseases (ALCER). 
The research team will analyze and interpret the findings from both the quantitative 
and qualitative components, applying a triangulation process to enhance the validity and 
depth of interpretation. The results will be structured around key thematic areas such as 
regional disparities, evaluation and KT access processes, healthcare professional training, 
and the influence of social and structural determinants. Based on this synthesis, technical 
briefs will be prepared to highlight the most relevant insights, propose improvement 
strategies, and identify aspects that require further attention. These materials will be 
shared with the ATRAE working groups and coordination bodies, with the goal of 
supporting evidence-based decision-making and facilitating the integration of research 
findings into ongoing national planning processes. 
Through this knowledge translation effort, the study positions itself as a relevant and 
timely contributor to the development of public policies, ensuring that its findings are not 
only scientifically rigorous but also transferable, actionable, and aligned with the 
institutional framework responsible for promoting equity in access to KT in Spain.  
ETHICS AND DISSEMINATION 
This project is grounded in the four fundamental ethical principles that guide health and 
social care research and practice: autonomy (respect for persons), beneficence, non-
maleficence, and justice. These principles are aligned with the ethical framework set out 
in the Declaration of Helsinki 38 and the Code of Ethics for Nurses 39. The study also 
complies with data protection regulations, including Spanish Organic Law 3/2018 of 5 
December, on Personal Data Protection and Guarantee of Digital Rights 40, and 
Regulation (EU) 2016/679 of the European Parliament and Council on data protection 41. 

The protocol was approved by the ethics committee of the study institution (Comitè 
d'Ètica de la Investigació amb Medicaments, “Ethics Committee for Research with 
Medicines”) under registration number 2025/12128/I. Each phase of the project will be 
governed by a specific research protocol, ensuring full compliance with all ethical and 
legal requirements. All participants will receive an information sheet and will sign an 
informed consent form prior to data collection. Any substantial amendments to the 
protocol will be submitted to the ethics committee before implementation. 
The study is expected to generate significant contributions to the identification of 
treatment deprivation and the improvement of care pathways for people with CKD in the 
Spanish healthcare system. It addresses a critical gap in current knowledge by exploring 
the hypothesis that structural, territorial, and professional factors may contribute to 
inequities in access to KT. By adopting a mixed-methods approach, this protocol aims to 
produce empirical evidence that will test and refine this hypothesis in the Spanish context. 
To ensure transparency and replicability, the methodological details will be clearly 
reported in all research outputs, enabling other researchers to apply or adapt the 
approaches used while upholding ethical standards. 
The findings of the study will be disseminated through peer-reviewed publications in 
high-impact journals and presented at national and international conferences to promote 
knowledge sharing and scientific dialogue. Dissemination efforts will also include non-
academic channels, such as social media, newsletters, and patient forums, to ensure 
accessibility and engagement among key stakeholders, including healthcare 
professionals, policymakers, and the general public. This multi-pronged dissemination 
strategy is designed to support the translation of evidence into clinical practice and health 
policy. 
Importantly, this project aligns with national strategic planning efforts, particularly the 
ATRAE initiative. In its final phase, the study will triangulate and translate the generated 
evidence into actionable recommendations to inform the development of the ATRAE 
consensus document. These findings will help identify priority intervention areas, support 
the reinforcement of existing strategies, and uncover unmet needs, thus contributing to 
the formulation of timely, relevant, and policy-oriented solutions. 
Operational challenges, such as the complexity of coordinating data collection across 
multiple healthcare centers, are anticipated. Addressing these challenges will require 

rigorous planning and collaboration with local teams to ensure consistency and 
representativeness across diverse regions. While the variability among healthcare settings 
may introduce complexity, it is also seen as an opportunity to enrich the analysis by 
capturing the heterogeneity of the Spanish healthcare landscape. 
Ultimately, the socially grounded and mixed-methods approach of this study is 
expected to offer a nuanced understanding of the mechanisms underlying inequity and 
treatment deprivation in access to KT. The insights generated may contribute to shaping 
public health strategies that are more equitable, efficient, and person-centered for 
individuals living with CKD. 
 
Abbreviations. AEU, Spanish Association of Urology; ALCER, National Federation of Associations for 
the Fight Against Kidney Diseases; ATRAE project, Optimizing Access to Kidney Transplantation in 
Spain; CIT-SNS, Transplant Commission of the Interterritorial Council of the Spanish National Health 
System; CKD, Chronic Kidney Disease; GRAMMS, Good Reporting of A Mixed Methods Study; KT, 
Kidney Transplantation; MeSH, Medical Subject Headings; ONT, Organización Nacional de Trasplantes; 
PRISMA, Preferred Reporting Items for Systematic Reviews and Meta-Analyses; RRT, Renal Replacement 
Therapy; SEDEN, Spanish Society of Nephrology Nursing; SEI, Spanish Society of Immunology; SEN, 
Spanish Society of Nephrology; SET, Spanish Transplant Society; SPSS, Statistical Package for the Social 
Sciences.  
Acknowledgements. The authors wish to acknowledge the future collaborations and institutional 
contributions that are expected to emerge during the course of this project. These forthcoming efforts will 
be essential to its successful implementation. 
Authors’ contributions. GPR, CV, and BDG made substantial contributions to the conception and design 
of the study. MSD, LRM, MSS, and EIC critically revised the manuscript for important intellectual content 
and will be part of the leading group of the project. All authors read and approved the final version of the 
manuscript. CV, EIC, and BDG contributed equally as senior authors and are part of the project’s core 
operational team, providing strategic, logistical, and administrative support. GPR takes responsibility for 
the paper as a whole and is the first and corresponding author. 
Funding. This study is funded and endorsed by the Spanish Organización Nacional de Trasplantes, with a 
total financial support of €74,597.49. Additional competitive funding opportunities will be pursued to 
expand and reinforce the financial support for the project. 
Availability of data and materials. The datasets generated during the proposed study protocol will be 
available from the frst author (GPR) upon reasonable request. 
Ethics approval and consent to participate. This protocol was approved by the ethics committee at the 
study institution (Comitè d'Ètica de la Investigació amb Medicaments, “Ethics Committee for Research 
with Medicines”) with registration number 2025/12128/I.  
Competing interests. The authors declare no competing interests.  
 
 
 
 
 

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REGULATION  (EU)  2016/  679  OF  THE  EUROPEAN  PARLIAMENT  AND  OF  T
HE  COUNCIL  -  of  27  April  2016  -  on  the  protection  of  natural  persons  with  regar
d  to  the  processing  of  personal  data  and  on  the  free  movement  of  such  data,  and  re
pealing  Directive 95/  46/  EC  (General  Data  Protection  Regulation).