Trends in the epidemiology of paediatric kidney transplantation in Europe between 2010 and 2021: an ESPN/ERA Registry study

Iris R Montez de Sousa; Ann Christin Gjerstad; Augustina Jankauskiene; Brankica Spasojević; Burkhard Tönshoff; Cyrielle Parmentier; Diamant Shtiza; Varvara Askiti; György Reusz; Gregor Novljan; Greta Mihneva-Kirilova; Ilona Zagożdżon; Jelena Stojanovic; Julien Hogan; Karel Vondrak; Liliana Rocha; Ludmila Podracka; Maria S Molchanova; Marc A G J ten Dam; Nora Abazi-Emini; Osman Dönmez; Sergey Baiko; Sevcan A Bakkaloglu; Søren Schwartz Sørensen; Svitlana P Fomina; Timo Jahnukainen; Torbjörn Lundgren; Vidar Edvardsson; Winnie Magadi; Kitty J Jager; Vianda S Stel; Marjolein Bonthuis

doi:10.1093/ckj/sfag012

. 2026 Jan 15;19(2):sfag012. doi: 10.1093/ckj/sfag012

Trends in the epidemiology of paediatric kidney transplantation in Europe between 2010 and 2021: an ESPN/ERA Registry study

Iris R Montez de Sousa ^1,^2,^✉, Ann Christin Gjerstad ³, Augustina Jankauskiene ⁴, Brankica Spasojević ^5,⁶, Burkhard Tönshoff ⁷, Cyrielle Parmentier ⁸, Diamant Shtiza ⁹, Varvara Askiti ¹⁰, György Reusz ¹¹, Gregor Novljan ^12,¹³, Greta Mihneva-Kirilova ¹⁴, Ilona Zagożdżon ¹⁵, Jelena Stojanovic ¹⁶, Julien Hogan ^17,¹⁸, Karel Vondrak ¹⁹, Liliana Rocha ²⁰, Ludmila Podracka ²¹, Maria S Molchanova ²², Marc A G J ten Dam ²³, Nora Abazi-Emini ²⁴, Osman Dönmez ²⁵, Sergey Baiko ²⁶, Sevcan A Bakkaloglu ²⁷, Søren Schwartz Sørensen ^28,²⁹, Svitlana P Fomina ³⁰, Timo Jahnukainen ^31,³², Torbjörn Lundgren ^33,³⁴, Vidar Edvardsson ^35,³⁶, Winnie Magadi ^37,³⁸, Kitty J Jager ^39,⁴⁰, Vianda S Stel ^41,⁴², Marjolein Bonthuis ^43,^44,⁴⁵

¹ESPN/ERA Registry, Department of Medical Informatics, Amsterdam UMC location University of Amsterdam, Amsterdam, The Netherlands

² Quality of Care Program, Amsterdam Public Health Research Institute, Amsterdam, The Netherlands

³ Division of Paediatric and Adolescent Medicine, Oslo University Hospital, Oslo, Norway

⁴ Vilnius University, Medical Faculty, Institute of Clinical Medicine, Pediatric Center, Vilnius, Lithuania

⁵ Nephrology, University Children’s Hospital, Belgrade, Serbia

⁶ Faculty of Medicine, University of Belgrade, Belgrade, Serbia

⁷Heidelberg University, Medical Faculty, Department of Pediatrics I, University Children’s Hospital Heidelberg, Heidelberg, Germany

⁸Department of Paediatric Nephrology, Armand-Trousseau Children’s Hospital, APHP, Paris, France

⁹ University Hospital Centre “Mother Tereza”, Tirana, Albania

¹⁰Pediatric Nephrology Department, Children’s Hospital “P. & A. Kyriakou”, Athens, Greece

¹¹Bókay Street Department, Pediatric Centre, Semmelweis University, Budapest, Hungary

¹²Pediatric Nephrology Department, University Children’s Hospital Ljubljana, Ljubljana, Slovenia

¹³Department of Pediatrics, Medical Faculty, University of Ljubljana, Ljubljana, Slovenia

¹⁴ Specialized Hospital for Active Treatment of Children’s Diseases “Prof. Ivan Mitev” Sofia, Medical University of Sofia, Sofia, Bulgaria

¹⁵Department of Pediatrics, Nephrology and Hypertension, Medical University of Gdansk, Gdansk, Poland

¹⁶ Great Ormond Street Hospital for Children, Institute for Child Health, University College London, London, UK

¹⁷ Université Paris Cité, INSERM Unité 970, Paris Institute for Transplantation and Organ Regeneration, Paris, France

¹⁸ Division of Pediatric Nephrology, Robert Debré Hospital, AP-HP, Paris, France

¹⁹Department of Pediatrics, 2nd Faculty of Medicine, Charles University Prague and University Hospital Prague - Motol. Prague, Czech Republic

²⁰ Centro Materno-Infantil do Norte, Unidade Local de Saúde de Santo António (ULSSA), Porto, Portugal

²¹Department of Pediatrics, Comenius University Medical School, Bratislava, Slovak Republic

²² Pirogov Russian National Research Medical University, Moscow, Russia

²³ Nefrodata Dutch Renal Registry, Utrecht, The Netherlands

²⁴ University Children’s Hospital, Medical Faculty of Skopje, North Macedonia

²⁵ Uludağ University, Faculty of Medicine, Division of Pediatric Nephrology and Rheumatology, Bursa, Türkiye

²⁶1st Department of Pediatrics, Belarusian State Medical University, Minsk, Belarus

²⁷Division of Pediatric Nephrology, Department of Pediatrics, Gazi University Faculty of Medicine, Ankara, Türkiye

²⁸Department of Nephrology, Rigshospitalet, Copenhagen University Hospital, Copenhagen, Denmark

²⁹Department of Clinical Medicine, University of Copenhagen, Copenhagen, Denmark

³⁰Department of Paediatric Nephrology, State Institution “National Scientific Center of Surgery and Transplantation named after O.O. Shalimov to National Academy of Medical Sciences of Ukraine”, Kyiv, Ukraine

³¹ Finnish Registry for Kidney Diseases, Helsinki, Finland

³²Department of Pediatric Nephrology and Transplantation, Children’s Hospital, Helsinki University Hospital and University of Helsinki, Helsinki, Finland

³³ Medical Unit of Transplantation, Karolinska University Hospital, Stockholm, Sweden

³⁴ Division of Transplantation Surgery, CLINTEC, Karolinska Institutet, Stockholm, Sweden

³⁵ Faculty of Medicine, University of Iceland, Reykjavík, Iceland

³⁶ Children’s Medical Center, Landspitali University Hospital, Reykjavík, Iceland

³⁷ UK Renal Registry, UK Kidney Association, Bristol, UK

³⁸Department of Population Health Sciences, Bristol Medical School, University of Bristol, Bristol, UK

³⁹ Quality of Care Program, Amsterdam Public Health Research Institute, Amsterdam, The Netherlands

⁴⁰ERA Registry, Department of Medical Informatics, Amsterdam UMC location University of Amsterdam, Amsterdam, The Netherlands

⁴¹ Quality of Care Program, Amsterdam Public Health Research Institute, Amsterdam, The Netherlands

⁴²ERA Registry, Department of Medical Informatics, Amsterdam UMC location University of Amsterdam, Amsterdam, The Netherlands

⁴³ESPN/ERA Registry, Department of Medical Informatics, Amsterdam UMC location University of Amsterdam, Amsterdam, The Netherlands

⁴⁴ Quality of Care Program, Amsterdam Public Health Research Institute, Amsterdam, The Netherlands

⁴⁵ERA Registry, Department of Medical Informatics, Amsterdam UMC location University of Amsterdam, Amsterdam, The Netherlands

^✉

Correspondence to: Iris R. Montez de Sousa; E-mail: i.r.montezdesousa@amsterdamumc.nl

PMCID: PMC12910316 PMID: 41710046

ABSTRACT

Background

Kidney transplantation (KT) is the preferred treatment for paediatric patients with kidney failure, but information on trends in paediatric KT in Europe is lacking. We aimed to report on time trends in paediatric (0–17 years) KT rates and recipient characteristics in Europe between 2010 and 2021.

Methods

Thirty-one countries contributing data from 2010 to 2021 on paediatric KT to the European Society for Paediatric Nephrology/European Renal Association Registry were included. We reported trends in KT rates [per million age-related population (pmarp)], overall and by patient subgroup for Europe, and at macro-economic and country-specific levels. We also reported clinical variables in the first year post-KT. The 2020–21 period was analysed separately to account for the COVID-19 pandemic.

Results

The paediatric KT rate was stable at ≈5 pmarp between 2010 and 2019, and about one-fourth were pre-emptive KTs. In 2020–21 the KT rate was 5.6 pmarp. In low–, middle– and high–gross domestic product (GDP) countries, KT rates (pmarp) were 2.1, 6.1 and 7.6, respectively, and increased in low-GDP countries by 4.1% per year from 2010 to 2019, mainly in the youngest recipients. The proportion of pre-emptive KT increased only in middle-GDP countries. Low-GDP countries showed a higher prevalence of short stature while high-GDP countries showed more overweight/obese, hypertensive and anaemic patients.

Conclusions

The rate of paediatric KT in Europe has remained stable, with differences between GDP groups. Low-GDP countries had the lowest KT rates, but with an increasing trend over time. Opportunities to further increase access to paediatric KT should be explored.

Keywords: epidemiology, Europe, kidney transplantation, paediatrics, trends

KEY LEARNING POINTS.

What was known:

Kidney transplantation (KT) is the preferred treatment modality for paediatric patients in need of kidney replacement therapy (KRT), leading to better growth, psychosocial development and quality of life, as well as longer life expectancy, and being more cost-effective than dialysis.
In Europe, there are inequalities among countries in access to paediatric KT, which may be related to various factors such as macro-economics, KRT selection procedures, transplantation policies, donation rates and KT practices.
KT rates in adult patients from Europe increased between 2010 and 2018, with large variations between countries. However, information on time trends in paediatric KT rates in Europe is lacking.

This study adds:

Between 2010 and 2019, the overall rate of paediatric (age 0–17 years) KT in Europe remained stable at ≈5 per million age-related population (pmarp). However, there were differences by gross domestic product (GDP) level: rates were 2.1 pmarp in low-, 6.1 pmarp in middle- and 7.6 pmarp in high-GDP countries. Approximately one in four kidney transplants was performed pre-emptively and the proportion of pre-emptive KTs increased only in the middle-GDP group.
Between 2010 and 2019, KT rates in low-GDP countries increased by 4.1% per year, mainly among very young children and among recipients of living donor kidney transplants.
The COVID-19 pandemic was not found to have a substantial impact on the overall paediatric KT rate in Europe, which was 5.6 pmarp in 2020–2021. However, in middle- and high-GDP countries, deceased donor KT rates seemed to decrease and the time on dialysis before KT increased slightly.

Potential impact:

This study provides an overview of trends in paediatric KT in nearly all European countries, suggesting an improvement in access to paediatric KT in low-GDP countries.
The findings of this study may support policymakers and the medical community in identifying barriers and opportunities to further increase access to paediatric KT overall and also pre-emptive KT.

INTRODUCTION

Kidney transplantation (KT) is the preferred treatment modality for paediatric patients who need kidney replacement therapy (KRT) [1–3], resulting in better psychosocial development and quality of life and longer life expectancy, while being more cost-effective than dialysis [1, 2, 4, 5]. Although only about one-fifth of the European children with kidney failure receive pre-emptive KT, the majority will receive a graft during childhood. By 31 December 2021, 73% of prevalent paediatric KRT patients in Europe (age <15 years) had a functioning kidney transplant [6, 7].

Country disparities in access to paediatric KT and recipient characteristics persist, possibly caused by macro-economic factors, KRT selection procedures and transplantation policies and practices [1, 5, 8, 9]. Well-resourced countries are usually able to accept more complex cases for KRT, including younger patients and those with more comorbidities [5, 9]. Furthermore, KRT care differences may have an impact on patients’ clinical variables, such as growth and haemoglobin levels and are associated with quality of life and graft and patient survival [10, 11]. Although several studies have shown differences in paediatric KT practices [1, 5, 9], and the European Society for Paediatric Nephrology (ESPN)/European Renal Association (ERA) Registry published annual reports on the epidemiology of paediatric dialysis and KT [6, 7, 12, 13], information on time trends in European paediatric KT is lacking [8]. Comprehensive epidemiological data on such trends and geographical variations can help in determining whether efforts to improve paediatric KRT care have been successful, highlighting potential areas for improvement [1, 5].

The aim of this ESPN/ERA Registry study was to investigate trends in the epidemiology of paediatric KT (age 0–17 years) in Europe in the period 2010–19. Additionally, we evaluated the trends of paediatric KT during the COVID-19 pandemic (2020–21). Specifically, we aimed to provide details on trends in KT rates and clinical variables at macro-economic and country-specific levels.

MATERIALS AND METHODS

Data sources

Data were extracted from the ESPN/ERA Registry, a population-based registry that annually collects information on individual paediatric KRT patients from renal registries in Europe [12]. Thirty-one countries contributing data on patients ages 0–17 years who received a kidney transplant, including retransplantations, between 1 January 2010 and 31 December 2021 were included, covering on average 86% of the general European paediatric population (Supplementary Table S1). In The Netherlands, there was (almost) no underreporting of (pre-emptive) KT in 2010–16, but some underreporting exists for overall KT in 2017–19 (ranging from 14% to 32%) and for pre-emptive KT in 2017–21 (ranging from 25% to 43%).

Participating European countries were categorized into low–, middle– and high–gross domestic product (GDP) groups based on tertiles of average GDP between 2010 and 2021 obtained from the World Bank database (Supplementary Table S1) [14].

Statistical analyses

Patient characteristics were described across periods, for Europe and by GDP group and presented as numbers (percentages). Primary renal diseases (PRDs) were grouped according to ERA Registry codes adapted for children [13]. Due to its low frequency, ischaemic kidney failure, haemolytic uraemic syndrome (HUS), metabolic diseases, vasculitis, miscellaneous and ‘other’ causes were combined into the category ‘other’ [13]. For countries that reported comorbidities (22 of 31), we hypothesized that comorbidities were absent if this information was missing [9]. Chi-squared tests were used to assess statistically significant differences in patient characteristics between GDP groups and time periods (2010–14 and 2015–19). To account for the potential impact of the COVID-19 pandemic on paediatric KT rates, the pandemic years (2020–21) were analysed separately.

KT rates were expressed per million age-related population (pmarp) and calculated by dividing the number of KTs in a year by the general population ages 0–17 years and multiplied by one million. General population counts were obtained from the Eurostat database [15]. Annual rates were calculated for all KTs performed in Europe, by country, and GDP group and stratified by age at KT, sex, PRD and donor type. Due to low annual paediatric KT rates per country, these were averaged and expressed per period (2010–14, 2015–19 and 2020–21) to obtain more stable estimates.

Time trends in KT rates were evaluated using the Joinpoint regression program, which estimates the annual percent change (APC) of a variable and allows the detection of time points at which the slope of the regression line changes significantly. It was therefore possible to identify statistically significant changes in KT rates over the study period. A detailed explanation of this method can be found elsewhere [16]. To avoid the potential impact of the COVID-19 pandemic, APC calculations were performed for the period 2010–19 [17]. The 10 data points included in the analyses allowed for the detection of a maximum of one joinpoint [18].

Several clinical variables, measured multiple times during the first year post-transplant, were described across periods, overall and by GDP group. These variables, reported as proportions [95% confidence interval (CI)], were short stature, overweight/obesity, hypertension, anaemia and hyperparathyroidism. Definitions of each clinical variable are provided in Supplementary Table S2. Generalised estimating equation models were used to correct for the correlation of multiple measurements at different time intervals in the same patient. Further details of this methodology can be found elsewhere [19].

Statistical tests were two-tailed and differences were considered statistically significant for P-values <.05. Data analyses were performed using SAS version 9.4 (SAS Institute, Cary, NC, USA) and Joinpoint 4.2.0.2 (2015; National Cancer Institute, Calverton, MD, USA).

RESULTS

Patient population

In Europe, the majority of paediatric kidney transplant recipients (KTRs) were male (59.5%), with congenital anomalies of the kidney and urinary tract (CAKUT) (36.0%), transplanted during adolescence (13–17 years; 40.3%). One-quarter of patients received a pre-emptive kidney transplant and one-third had comorbidities (Table 1). In low-GDP countries, compared with middle- and high-GDP groups, fewer patients received a kidney transplant at a very young age (0–5 years), were transplanted pre-emptively or had comorbidities (Table 2).

Table 1:

Characteristics of paediatric KTRs overall and stratified by time period of KT.

Characteristics	2010–19	2010–14	2015–19	2020–21^a	P-value (2010–14 versus 2015–19)
	Period of kidney transplantation
Patients, n (%)	6611 (100.0)	3212 (48.6)	3399 (51.4)	1167
Age at kidney transplantation (years), n (%)
0–5	1554 (23.5)	744 (23.2)	810 (23.8)	250 (21.4)	0.539
6–12	2393 (36.2)	1184 (36.9)	1209 (35.6)	424 (36.3)
13–17	2664 (40.3)	1284 (40.0)	1380 (40.6)	493 (42.3)
Age at kidney transplantation (years), median (IQR)	11.5 (6.3–15.0)	11.5 (6.2–15.0)	11.4 (6.5–15.1)	11.7 (6.8–15.3)
Males, n (%)	3930 (59.5)	1891 (58.9)	2039 (60.0)	716 (61.4)	0.348
Age at KRT start (years), n (%)
0–5	2183 (33.0)	1049 (32.7)	1134 (33.4)	408 (35.0)	0.229
6–12	2457 (37.2)	1221 (38.0)	1236 (36.4)	434 (37.2)
13–17	1962 (29.7)	940 (29.3)	1022 (30.1)	322 (27.6)
Unknown	9 (0.1)	2 (0.1)	7 (0.2)	3 (0.3)
Primary renal disease^b, n (%)
Glomerulonephritis	1037 (15.7)	499 (15.5)	538 (15.8)	179 (15.4)	0.002
CAKUT	2377 (36.0)	1158 (36.1)	1219 (35.9)	396 (33.9)
Cystic kidney disease	874 (13.2)	405 (12.6)	469 (13.8)	159 (13.6)
Hereditary nephropathy	437 (6.6)	198 (6.2)	239 (7.0)	72 (6.2)
Other	1255 (19.0)	598 (18.6)	657 (19.3)	224 (19.2)
Unknown	631 (9.5)	354 (11.0)	277 (8.2)	137 (11.7)
Initial treatment modality^c, n (%)
Haemodialysis	2194 (36.4)	1037 (35.0)	1157 (37.7)	368 (36.9)	0.019
Peritoneal dialysis	2240 (37.1)	1146 (38.7)	1094 (35.6)	378 (37.9)
KT	1487 (24.7)	715 (24.2)	772 (25.1)	236 (23.7)
Unknown	111 (1.8)	63 (2.1)	48 (1.6)	16 (1.6)
Comorbidities, n (%)^d
Yes	1513 (33.0)	723 (31.8)	790 (34.2)	273 (34.8)	0.078
No	3074 (67.0)	1554 (68.3)	1520 (65.8)	511 (65.2)
Time on dialysis before first KT (months)^c,e, n (%)
0	1492 (24.8)	718 (24.3)	774 (25.3)	236 (23.7)	0.341
>0–6	921 (15.3)	458 (15.5)	463 (15.1)	114 (11.5)
>6–12	998 (16.6)	500 (16.9)	498 (16.3)	137 (13.8)
>12–24	1255 (20.8)	640 (21.6)	615 (20.1)	217 (21.8)
>24	1359 (22.6)	644 (21.8)	715 (23.3)	291 (29.3)
Kidney donor type, n (%)
Deceased	3745 (56.7)	1859 (57.9)	1886 (55.5)	573 (49.1)	<0.001
Living	2348 (35.5)	1064 (33.1)	1284 (37.8)	386 (33.1)
Unknown	518 (7.8)	289 (9.0)	229 (6.7)	208 (17.8)

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Significant values in bold.

Data from Russia are not included in the period 2020–21.

The PRD category ‘other’ includes ischaemic kidney failure, haemolytic uraemic syndrome, metabolic diseases, vasculitis, miscellaneous and others.

Türkiye presents an overestimation of pre-emptive KT and therefore underestimation of the true time on dialysis before first KT, hence it was excluded from this analysis.

Countries that did not report data on comorbidities between 2010 and 2019 were excluded from this analysis (Austria, Denmark, Finland, France, Iceland, The Netherlands, Romania, Sweden and Ukraine). The following comorbidity categories were included: cardiovascular disease, chronic inflammatory disease, chronic intestinal disease, liver disease, multiple malformative syndrome, malignancy, neurological disorders, chronic pulmonary disease, systemic disease, preterm birth, developmental delay, chromosomal anomaly and diabetes mellitus.

There were seven patients with unknown time on dialysis before the first KT between 2010 and 2019 due to unknown date of KRT start.

Table 2:

Characteristics of paediatric KTRs stratified by GDP group between 2010 and 2019.

Characteristics	Low	Middle	High	P-value^c
	GDP group
Patients who received a kidney transplant (% of all prevalent KRT patients)^a	45.5	71.5	78.8	N/A
Patients, n (%)^b	1517 (23.0)	1565 (23.7)	3529 (53.4)
Age at KT (years), n (%)
0–5	288 (19.0)	317 (20.3)	949 (26.9)	<0.001
6–12	613 (40.4)	609 (38.9)	1171 (33.12)
13–17	616 (40.6)	639 (40.8)	1409 (39.9)
Age at KT (years), median (IQR)	11.9 (7.9–14.7)	11.6 (6.9–15.0)	11.4 (5.6–15.4)
Males, n (%)	876 (57.8)	922 (59.0)	2132 (60.4)	0.187
Age at KRT start (years), n (%)
0–5	414 (27.3)	489 (31.3)	1280 (36.3)	<0.001
6–12	694 (45.8)	623 (39.8)	1140 (32.3)
13–17	406 (26.8)	447 (28.6)	1109 (31.4)
Unknown	3 (0.2)	6 (0.4)	0 (0.0)
Primary renal disease^d, n (%)
Glomerulonephritis	245 (16.2)	282 (18.0)	510 (14.5)	<0.001
CAKUT	526 (34.7)	507 (32.4)	1344 (38.1)
Cystic kidney disease	217 (14.3)	215 (13.7)	442 (12.5)
Hereditary nephropathy	47 (3.1)	99 (6.3)	291 (8.3)
Other	304 (20.0)	343 (21.9)	608 (17.2)
Unknown	178 (11.7)	119 (7.6)	334 (9.5)
Initial treatment modality^e, n (%)
Haemodialysis	432 (46.1)	526 (33.6)	1236 (35.0)	<0.001
Peritoneal dialysis	363 (38.7)	689 (44.0)	1188 (33.7)
Kidney transplantation	135 (14.4)	340 (21.7)	1012 (28.7)
Unknown	8 (0.9)	10 (0.6)	93 (2.6)
Comorbidities^f, n (%)
Yes	210 (16.0)	739 (47.2)	564 (33.1)	<0.001
No	1107 (84.1)	826 (52.8)	1141 (66.9)
Time on dialysis before first KT (months)^e,g, n (%)
0	136 (14.5)	341 (21.9)	1015 (28.8)	<0.001
>0–6	208 (22.2)	237 (15.2)	476 (13.5)
>6–12	174 (18.6)	269 (17.3)	555 (15.7)
>12–24	196 (20.9)	323 (20.7)	736 (20.9)
>24	223 (23.8)	389 (25.0)	747 (21.2)
Kidney donor type, n (%)
Deceased	661 (43.6)	1058 (67.6)	2026 (57.4)	<0.001
Living	706 (46.5)	238 (15.2)	1404 (39.8)
Unknown	150 (9.9)	269 (17.2)	99 (2.8)

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Significant values in bold.

The percentages in this row correspond to the average proportion in 2010–19 of prevalent KRT patients (including dialysis) with a functioning kidney transplant by the end of the year in each GDP group.

The percentages in this row correspond to the proportion of KTRs in each GDP group from the total number of KTRs in Europe.

P-values comparing GDP groups.

The PRD category ‘other’ includes ischaemic kidney failure, haemolytic uraemic syndrome, metabolic diseases, vasculitis, miscellaneous and others.

Turkey presents an overestimation of pre-emptive KT and therefore an underestimation of the true time on dialysis before first KT, hence it was excluded from this analysis.

There were seven patients with unknown time on dialysis before the first KT between 2010 and 2019 due to unknown date of KRT start.

Trends in KT

Total KT in Europe and by GDP group

The annual paediatric KT rate was stable between 2010 and 2019: 4.9 pmarp in 2010–14 and 5.1 pmarp in 2015–19 [APC 0.1 (95% CI −1.1 to 1.2)]. Between 2010 and 2019 there was considerable variation between countries in KT rates, ranging from 1.1 pmarp in Romania to 9.5 pmarp in Finland and Sweden (Table 3, Fig. 1). The low-GDP group had the lowest KT rate; however, it increased significantly over time from 1.9 pmarp in 2010–14 to 2.4 pmarp in 2015–19 [APC 4.1 (95% CI 1.6 to 6.7)] (Table 3, Fig. 1). The average KT rate was stable in the middle- (6.1 pmarp both in 2010–14 and 2015–19) and high- (7.6 and 7.5 pmarp in 2010–14 and 2015–19, respectively) GDP groups.

Table 3:

KT rates (pmarp) and proportion of pre-emptive KTs in 0- to 17-year-olds, by country and time period.

Country	2010–2014	2015–2019	2020–2021^a	Average 2010–2019
	KT (pre-emptive KT)
Low GDP
Albania	0.8 (0.0)	1.8 (0.0)	1.7 (0.0)	1.3 (0.0)
Belarus	7.2 (3.3)	4.0 (2.2)	5.1 (19.6)	5.6 (2.7)
Bulgaria	0.7 (0.0)	3.5 (30.2)	4.2 (60.0)	2.1 (15.1)
North Macedonia	1.8 (0.0)	1.9 (30.0)	3.7 (25.0)	1.9 (15.0)
Republic of Serbia	5.0 (14.5)	2.3 (10.0)	1.3 (0.0)	3.6 (12.3)
Romania	1.0 (10.0)	1.3 (10.0)	1.9 (0.0)	1.1 (10.0)
Russia	1.8 (16.8)	2.3 (15.4)	N/A	2.0 (16.1)
Ukraine	1.1 (2.5)	2.9 (18.1)	3.5 (10.7)	2.0 (10.3)
Türkiye	2.2 (76.5)	2.9 (58.8)	3.7 (18.6)	2.5 (67.6)
Total^b	1.9 (12.1)	2.4 (15.2)	3.2 (15.7)	2.1 (13.6)
Middle GDP
Croatia	5.0 (16.7)	3.0 (5.0)	0.0 (0.0)	4.0 (10.8)
Czech Republic	4.9 (10.6)	4.2 (18.2)	3.0 (0.0)	4.5 (14.4)
Estonia	1.6 (10.0)	3.2 (20.0)	5.8 (0.0)	2.4 (15.0)
Greece	4.0 (16.5)	3.2 (16.7)	7.0 (12.4)	3.6 (16.6)
Hungary	6.0 (15.4)	5.6 (8.9)	3.2 (36.7)	5.8 (12.2)
Lithuania	4.6 (0.0)	6.3 (35.0)	5.0 (12.5)	5.5 (17.5)
Malta	0.0 (0.0)	2.6 (20.0)	0.0 (0.0)	1.3 (10.0)
Poland	5.9 (12.1)	5.4 (13.8)	4.6 (10.5)	5.7 (12.9)
Portugal	8.7 (12.8)	8.4 (27.2)	5.9 (22.0)	8.5 (20.0)
Slovakia	3.7 (6.7)	3.0 (5.0)	1.5 (75.0)	3.3 (5.8)
Slovenia	6.2 (0.0)	5.5 (0.0)	4.0 (0.0)	5.9 (0.0)
Spain	7.2 (24.4)	8.0 (33.0)	8.2 (35.7)	7.6 (28.7)
Total	6.1 (16.8)	6.1 (22.9)	5.5 (24.6)	6.1 (19.9)
High GDP
Austria	6.2 (24.6)	8.3 (35.8)	5.8 (39.6)	7.2 (30.2)
Denmark	7.0 (38.9)	7.7 (45.4)	4.8 (32.1)	7.4 (42.2)
Finland	8.7 (6.5)	10.3 (21.7)	9.6 (35.9)	9.5 (14.1)
France	6.3 (25.7)	7.0 (22.3)	6.0 (11.4)	6.6 (24.0)
Germany	4.5 (23.5)	4.5 (19.4)	3.3 (18.9)	4.5 (21.4)
Iceland	7.5 (20.0)	2.5 (0.0)	6.1 (0.0)	5.0 (10.0)
Norway	8.8 (33.6)	7.3 (69.0)	8.5 (30.7)	8.0 (51.3)
Sweden	10.3 (34.1)	8.7 (28.5)	8.2 (41.9)	9.5 (31.3)
The Netherlands^c	7.6 (34.6)	6.5 (46.3)	4.7 (38.5)	7.0 (40.5)
UK	8.6 (30.9)	8.0 (25.6)	7.5 (25.0)	8.3 (28.3)
Total^b	7.6 (29.2)	7.5 (28.0)	6.7 (23.3)	7.6 (28.6)
Total overall^b	4.9 (22.8)	5.1 (24.2)	5.6 (22.7)	5.0 (23.5)

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Data from Russia are not included in the period of 2020–21.

Data from the German transplantation registry are not based on all the transplantation centres in the country. The incidence in Türkiye is an underestimation of the true incidence. Therefore Germany and Türkiye were excluded from the overall estimates.

In The Netherlands, there was (almost) no underreporting of (pre-emptive) KT in 2010–16, but some underreporting exists for overall KT in 2017–19 (ranging from 14% to 32%) and for pre-emptive KT in 2017–2021 (ranging from 25% to 43%).

Figure 1: — Average kidney transplantation rate (pmarp) in 0-17 year-olds overall, by GDP, and by country, in the periods of 2010-2014, 2015-2019 and 2020-2021. Annual trends were calculated by the APC (95% CI).

Pre-emptive KT in Europe and by GDP group

Of all the KTs performed (including retransplantation) between 2010 and 2019, the average overall proportion of pre-emptive KTs was 23.5%. In low-, middle- and high-GDP groups it was, respectively, 13.6%, 19.9% and 28.6% (Table 3). Between 2010 and 2019 the overall proportion of pre-emptive KTs remained stable but increased in the middle-GDP group (Supplementary Table S3).

Trends in KT by patient subgroup

Age at KT

KT rates were lowest among children ages 0–5 years (3.4 pmarp in both 2010–14 and 2015–19) and highest among adolescents (13–17 years; 7.0 pmarp in 2010–14 and 7.8 pmarp in 2015–19). There were no significant time trends in KT rates by age group, except in the low-GDP group. Despite the lowest KT rates among 0- to 5-year-olds, it increased on average by 9.3% per year (95% CI 4.5 to 14.4), from 0.9 pmarp in 2010–14 to 1.5 pmarp in 2015–19 (Fig. 2, Supplementary Table S3).

Figure 2: — Kidney transplantation rate (pmarp) in 0-17 year-olds overall and per GDP, stratified by age at kidney transplantation in 2010-2014, 2015-2019 and 2020-2021.

Sex

Overall, the KT rate in 2010–19 in males (5.8 pmarp) was higher compared with females (4.2 pmarp) and there were no temporal trends by sex (Fig. 3). In low-GDP countries, we observed an increase in the rate of KT for males, with an average of 4.5% per year (95% CI 0.3 to 8.9), and a similar (non-significant) increase for females [APC 3.8 (95% CI −1.3 to 9.2)] (Supplementary Table S3).

Figure 3: — Kidney transplantation rate (pmarp) in 0-17 year-olds overall and per GDP, stratified by sex in 2010-2014, 2015-2019 and 2020-2021.

PRD

Overall, trends in KT rates by PRD group were stable (Fig. 4). In the high-GDP group there was a decrease in paediatric KTRs with ‘other’ PRD [APC −4.9 (95% CI −7.7 to −2.0)] and an increase in cystic kidney disease [APC: 3.6 (95% CI 1.6 to 5.6)].

Figure 4: — Kidney transplantation rate (pmarp) in 0-17 year-olds overall and per GDP, stratified by PRD in 2010-2014, 2015-2019 and 2020-2021.

Donor type

Overall, there was a slight (non-significant) increase in the rate of living donor KTs between 2010 and 2019 [APC 1.5 (95% CI −0.6 to 3.7)] and the rate of deceased donor KTs remained stable [APC −1.1 (95% CI −3.1 to 1.0)] (Supplementary Fig. S1). When stratifying by GDP group, the increase in the living donor KT rate was only significant in the low-GDP group [APC 6.6 (95% CI 2.0 to 11.5)].

Growth, body mass index (BMI), anaemia and hyperparathyroidism

Between 2010 and 2019, during the first year post-transplant, almost half of all patients had short stature [43.1% (95% CI 41.5 to 44.7)], approximately one-third were overweight/obese [32.8% (95% CI 31.2 to 34.5)] or hypertensive [33.1% (95% CI 31.6 to 34.7)], 16.7% had anaemia (95% CI 15.6 to 17.9) and 53.1% (95% CI 50.5 to 55.6) had hyperparathyroidism (Table 4). The proportion of patients with short stature decreased slightly between periods, while the prevalence of anaemia increased (Table 4). There were more paediatric KTRs with short stature in the low-GDP group [54.3% (95% CI 51.0 to 57.7)]. In the high-GDP group, higher proportions of patients were overweight/obese [35.2% (95% CI 32.8 to 37.7)], hypertensive [35.5% (95% CI 33.5 to 37.6)] and anaemic [18.4% (95% CI 17.0 to 19.8)] (Table 5).

Table 4:

Clinical variables of paediatric KTRs overall and stratified by period of KT.

Clinical variables^a	2010–19	2010–14	2015–19	2020–21^b
	Period of kidney transplantation
Hypertension, % (95% CI)	n = 2553	n = 1254	n = 1300	n = 406
	33.1 (31.6–34.7)	34.3 (32.1–36.6)	32.1 (30.0–34.3)	31.5 (27.7–35.6)
Short stature, % (95% CI)	n = 3496	n = 1706	n = 1795	n = 454
	43.1 (41.6–44.7)	45.1 (42.8–47.4)	41.2 (39.1–43.4)	35.4 (31.2–39.7)
Overweight, % (95% CI)	n = 3490	n = 1704	n = 1791	n = 454
	32.8 (31.2–34.5)	33.9 (31.5–36.3)	32.0 (29.7–34.3)	31.8 (27.7–36.3)
Anaemia, % (95% CI)	n = 2807	n = 1400	n = 1407	n = 457
	16.7 (15.6–17.9)	14.5 (13.1–16.0)	18.5 (17.0–20.3)	16.9 (14.2–20.0)
Hyperparathyroidism, % (95% CI)	n = 1267	n = 615	n = 652	n = 228
	53.1 (50.5–55.6)	50.3 (46.6–54.0)	55.8 (52.3–59.3)	55.4 (48.7–61.8)

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Generalized estimating equation models were used to correct for correlations of multiple measurements within the same patient.

Data from Russia are not included in the period of 2020–21.

Definitions of each clinical variable are provided in Supplementary Table S2.

Table 5:

Clinical variables of paediatric KTRs stratified by GDP group between 2010 and 2019.

Clinical variables^a	Low	Middle	High
	GDP group
Hypertension, % (95% CI)	n = 246	n = 1032	n = 1275
	28.9 (24.6–33.7)	29.4 (26.8–32.2)	35.5 (33.5–37.6)
Short stature, % (95% CI)	n = 817	n = 1116	n = 1563
	54.3 (51.0–57.7)	37.8 (35.1–40.7)	41.3 (39.0–43.6)
Overweight, % (95% CI)	n = 816	n = 1116	n = 1558
	29.3 (25.9–32.9)	29.8 (27.1–32.6)	35.2 (32.8–37.7)
Anaemia, % (95% CI)	n = 313	n = 823	n = 1671
	10.2 (7.9–13.0)	11.9 (10.0–14.1)	18.4 (17.0–19.8)
Hyperparathyroidism, % (95% CI)	n = 153	n = 648	n = 466
	52.6 (45.8–59.3)	53.8 (50.2–57.3)	52.7 (48.7–56.6)

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Generalized estimating equation models were used to correct for correlations of multiple measurements within the same patient.

Definitions of each clinical variable are provided in Supplementary Table S2.

COVID-19 period (2020–21)

Paediatric KT rates remained stable in 2020–21 but the middle- and high-GDP groups showed a slight non-significant decrease (Table 3). Additionally, time on dialysis increased slightly, 51.1% of the KTRs in 2020–21 received ≥12 months of pretransplant dialysis, compared with 43.4% of patients transplanted in 2010–19 (Table 1).

DISCUSSION

In Europe, overall paediatric KT rates and pre-emptive KT rates have remained stable over the last decade. There were considerable differences between countries and GDP groups. The lowest rate was observed in the low-GDP group, but with an annual increase of 4.1%, which was not observed in the middle- and high-GDP countries.