Farewell from the CKJ Editor-in-Chief: key kidney topics from 2014 to 2021.

The year 2021 was the last full year of Alberto Ortiz's editorship at Clinical Kidney Journal (CKJ). On May 2022, Maria José Soler will start her term as the Editor-in-Chief. Over these years, CKJ obtained its first journal impact factor and has consolidated its position among the top journals in the field, consistently ranking among the top 25% (first quartile) journals in Urology and Nephrology. The 2020 journal impact factor rose to 4.45, becoming the top open access journal in Nephrology and the ninth ranked Nephrology journal overall. We now review the recent history of the journal and the most highly cited topics which include the epidemiology of kidney disease, chronic kidney disease topics, such as the assessment and treatment of chronic kidney disease, onconephrology, cardionephrology, glomerular disease, transplantation and coronavirus disease 2019 (COVID-19).

In 2008, the European Renal Association (ERA, formerly European Dialysis and Transplant Association, ERA-EDTA) launched a new journal, NDT Plus, under the editorship of Norbert Lameire (Figure 1). In 2012, NDT Plus evolved into the Clinical Kidney Journal (CKJ), under the leadership of Alain Meyrier. From 2014 onward, Alberto Ortiz has been the Editor-in-Chief (EiC), a term that will end in May 2022 when Maria José Soler will become the first female CKJ EiC [1, 2]. As the last full year as EiC ends, it is worth reflecting on the path so far and on the most impactful topics published in CKJ.

FIGURE 1:

Key milestones in the history of CKJ. Source for journal ranking: reference number [3].

THE FIRST JOURNAL IMPACT FACTOR

The single event that has most influenced the trajectory of the journal during Alberto Ortiz’s editorship was the journal's first impact factor (JIF) in 2019 [3]. Overnight, the number of submissions doubled and the quality increased, forcing the editorial board to make painful rejection decisions. Triaging became necessary and the acceptance rate for original manuscripts dropped to 10–15%. As of January 2021, the number of issues increased from 6 to 12 a year, to accelerate the speed of publication of new science.

From the first JIF, CKJ has been part of the select group of journals ranked among the top 25% (first quartile, Q1) of Urology and Nephrology journals. Moreover, as the JIF progressively increased to over 3.0 and, most recently, to over 4.0, CKJ slowly climbed the ranks of Q1 journals. As of the summer of 2021, the 2020 JIF was 4.452 and Clarivate ranked CKJ as the top open access Nephrology journal and the ninth Nephrology journal overall (Table 1). It was also the sixth ranked Nephrology journal among journals that publish mainly original research.

Table 1.

Top nephrology journals according to the 2020 Clarivate JIF ranking

(A) Overall Nephrology journals
Ranking	Journal name	2020 JIF	% of open access Gold manuscripts
1	Nature Reviews Nephrology	28.314	4%
2	Kidney International	10.612	19%
3	Kidney International Supplements	10.545	5%
4	Journal of the American Society of Nephrology	10.121	2%
5	American Journal of Kidney Diseases	8.860	8%
6	Clinical Journal of the American Society of Nephrology	8.237	1%
7	Nephrology Dialysis Transplantation	5.992	18%
8	Seminars in Nephrology	5.299	4%
9	Clinical Kidney Journal	4.452	100%

CKJ in bold.

Source: Reference number [3].

MOST IMPACTFUL NEPHROLOGY TOPICS IN CKJ OVER THE YEARS

It is worth reflecting on the items that drew the most citations over the years, the ones that most impacted other scientists and, potentially, clinical practice. The most cited manuscripts are presented in Table 2 and summarized per topic in Figure 2 [4-37]. Older items have had more time to build awareness and be cited and thus may be overrepresented. This issue is only partially addressed by the column depicting average citations per year, as there will be a lag time from publication to first notice by readers and to citation in the readers’ manuscript, and this will be followed by a lag time from manuscript submission to publication. Thus, citations shown in Table 2 will more accurately reflect the impact of older items than of newer items, whose full impact will be realized in the next few years. To visualize newer items, Table 3 shows the top publications ranked according to average yearly citations and Table 4 the top five cited manuscripts from each year [38-83]. While only one manuscript from 2019 or later is among the manuscripts with most overall citations (Table 2), 45% of manuscripts with the most annualized citations were from 2019 to 2021, illustrating the increased quality and visibility of CKJ contents (Table 3).

Table 2.

Most cited manuscripts published in CKJ 2014–2021, ERA Registry summary manuscripts excluded

Rank	Title	Author	Year	Total citations	Citations per year
1	The potential for improving cardio-renal outcomes by sodium-glucose co-transporter-2 inhibition in people with chronic kidney disease: a rationale for the EMPA-KIDNEY study	Herrington	2018	110	28
2	Effects of exercise in the whole spectrum of chronic kidney disease: a systematic review	Barcellos	2015	99	14
3	Iohexol plasma clearance for measuring glomerular filtration rate in clinical practice and research: a review. Part 1: How to measure glomerular filtration rate with iohexol?	Delanaye	2016	96	16
4	Chronic kidney disease in children	Becherucci	2016	83	14
5	The global nephrology workforce: emerging threats and potential solutions!	Sharif	2016	76	13
6	Chronic kidney disease hotspots in developing countries in South Asia	Abraham	2016	74	12
7	Macrophage in chronic kidney disease	Guiteras	2016	72	12
8	Iohexol plasma clearance for measuring glomerular filtration rate in clinical practice and research: a review. Part 2: Why to measure glomerular filtration rate with iohexol?	Delanaye	2016	69	12
9	Severe acute interstitial nephritis after combination immune-checkpoint inhibitor therapy for metastatic melanoma	Murakami	2016	64	11
10	Frailty and chronic kidney disease: current evidence and continuing uncertainties	Nixon	2018	63	16
11	A renal registry for Africa: first steps	Razeen Davids	2016	61	10
11	Analysis of ABCG2 and other urate transporters in uric acid homeostasis in chronic kidney disease: potential role of remote sensing and signaling	Bhatnagar	2016	61	10
12	The intestine and the kidneys: a bad marriage can be hazardous	Vanholder	2015	60	9
13	Lymphatic disorders after renal transplantation: new insights for an old complication	Ranghino	2015	57	8
14	A comparative analysis of survival of patients on dialysis and after kidney transplantation	Kaballo	2018	56	14
14	2017 update on pain management in patients with chronic kidney disease	Chi Pham	2017	56	11
14	Urinary peptide-based classifier CKD273: towards clinical application in chronic kidney disease	Pontillo	2017	56	11
14	The effects of vitamin K supplementation and vitamin K antagonists on progression of vascular calcification: ongoing randomized controlled trials	Caluwe	2016	56	9
15	Real-time ultrasound-guided percutaneous renal biopsy with needle guide by nephrologists decreases post-biopsy complications	Prasad	2015	55	8
15	Nephrology care prior to end-stage renal disease and outcomes among new ESRD patients in the USA	Gillespie	2015	55	8
16	Pathophysiological role of different tubular epithelial cell death modes in acute kidney injury	Sancho-Martinez	2015	54	8
16	Anticoagulation in chronic kidney disease patients—the practical aspects	Hughes	2014	54	7
17	Transplant renal artery stenosis: clinical manifestations, diagnosis and therapy	Chen	2015	52	7
18	The Stockholm CREAtinine Measurements (SCREAM) project: protocol overview and regional representativeness	Runesson	2016	51	9
19	Gut microbiota and inflammation in chronic kidney disease patients	Mafra	2015	50	7
19	Renal toxicities associated with pembrolizumab	Izzedine	2019	50	17
19	Nephrotoxicity of recent anti-cancer agents	Lameire	2014	50	6
20	A circulating permeability factor in focal segmental glomerulosclerosis: the hunt continues	Wada	2015	49	7
20	Risk factors associated with post-kidney transplant malignancies: an article from the Cancer-Kidney International Network	Sprangers	2018	49	12

Source: Reference number [4].

FIGURE 2:

Topics of most highly cited manuscripts published in CKJ between 2014 and October 2021. Extracted from Table 2.

Source: Reference number [4].

Table 3.

Most cited manuscripts published in CKJ 2014–2021 ranked per average yearly citations

Rank	Title	First author	Year	Total citations	Citations per year
1	The potential for improving cardio-renal outcomes by sodium-glucose co-transporter-2 inhibition in people with chronic kidney disease: a rationale for the EMPA-KIDNEY study	Herrington	2018	110	28
2	Characterization of acute kidney injury in critically ill patients with severe coronavirus disease 2019	Rubin	2020	35	17.5
3	Renal toxicities associated with pembrolizumab	Izzedine	2019	50	17
3	External validation of prognostic models: what, why, how, when and where?	Ramspek	2021	17	17
4	Iohexol plasma clearance for measuring glomerular filtration rate in clinical practice and research: a review. Part 1: How to measure glomerular filtration rate with iohexol?	Delanaye	2016	96	16
4	Frailty and chronic kidney disease: current evidence and continuing uncertainties	Nixon	2018	63	16
4	Daprodustat for anemia: a 24-week, open-label, randomized controlled trial in participants on hemodialysis	Meadowcroft	2019	48	16
5	Effects of a medium cut-off (Theranova ®) dialyser on haemodialysis patients: a prospective, cross-over study	Cozzolino	2021	15	15
6	Effects of exercise in the whole spectrum of chronic kidney disease: a systematic review	Barcellos	2015	99	14
6	Chronic kidney disease in children	Becherucci	2016	83	14
6	A comparative analysis of survival of patients on dialysis and after kidney transplantation	Kaballo	2018	56	14
6	Patterns of medication use and the burden of polypharmacy in patients with chronic kidney disease: the German Chronic Kidney Disease study	Schmidt	2019	41	14
7	Coronavirus disease 2019 in chronic kidney disease	D'Marco	2020	27	13.5
8	The global nephrology workforce: emerging threats and potential solutions!	Sharif	2016	76	13
9	Anemia and iron deficiency among chronic kidney disease Stages 3–5ND patients in the Chronic Kidney Disease Outcomes and Practice Patterns Study: often unmeasured, variably treated	Wong	2020	25	12.5
9	Acute kidney injury and kidney replacement therapy in COVID-19: a systematic review and meta-analysis	Fu	2020	25	12.5
10	Risk factors associated with post-kidney transplant malignancies: an article from the Cancer-Kidney International Network	Sprangers	2018	49	12
10	Macrophage in chronic kidney disease	Guiteras	2016	72	12
10	Chronic kidney disease hotspots in developing countries in South Asia	Abraham	2016	74	12
10	Air pollution and kidney disease: review of current evidence	Afsar	2019	36	12
10	Iohexol plasma clearance for measuring glomerular filtration rate in clinical practice and research: a review. Part 2: Why to measure glomerular filtration rate with iohexol?	Delanaye	2016	69	12
11	2017 update on pain management in patients with chronic kidney disease	Chi Pham	2017	56	11
11	Women and kidney disease: reflections on World Kidney Day 2018	Piccoli	2018	45	11
11	Acute kidney injury pathology and pathophysiology: a retrospective review	Gaut	2021	11	11
11	Urinary peptide-based classifier CKD273: towards clinical application in chronic kidney disease	Pontillo	2017	56	11
11	Routinely measuring symptom burden and health-related quality of life in dialysis patients: first results from the Dutch registry of patient-reported outcome measures	van der Willik	2021	11	11
11	Severe acute interstitial nephritis after combination immune-checkpoint inhibitor therapy for metastatic melanoma	Murakami	2016	64	11
11	Daprodustat for anemia: a 24-week, open-label, randomized controlled trial in participants with chronic kidney disease	Holdstock	2019	33	11
11	What do epidemiological studies tell us about chronic kidney disease of undetermined cause in Meso-America? A systematic review and meta-analysis	Gonzalez-Quiroz	2018	43	11
12	Clarifying the concept of chronic kidney disease for non-nephrologists	Perez-Gomez	2019	31	10
12	A renal registry for Africa: first steps	Razeen Davids	2016	61	10
12	Analysis of ABCG2 and other urate transporters in uric acid homeostasis in chronic kidney disease: potential role of remote sensing and signaling	Bhatnagar	2016	61	10
12	The keys to control a COVID-19 outbreak in a haemodialysis unit	Rincon	2020	20	10

Bold denotes manuscripts not presented in Table 2, representing more recent manuscripts with high average yearly citations but with a lower number of years in which they could be cited. ERA Registry summary manuscripts excluded.

Source: Reference number [4].

Table 4.

Top cited manuscripts from each year ranked per total citations

Year	Rank	Title	First author	Total citations	Average per year
2014	1	Anticoagulation in chronic kidney disease patients—the practical aspects	Hughes	54	7
	2	Nephrotoxicity of recent anti-cancer agents	Lameire	50	6
	3	CKD hotspots around the world: where, why and what the lessons are. A CKJ review series	Martin-Cleary	41	5
	3	Renal replacement therapy in Latin American end-stage renal disease	Rosa-Diez	41	5
	4	Incidence of acute kidney injury following total joint arthroplasty: a retrospective review by RIFLE criteria	Kimmel	40	5
	4	Focal and segmental glomerulosclerosis: clinical and kidney biopsy correlations	Sethi	40	5
	5	Amyloid nephropathy	Khalighi	34	4
2015	1	Effects of exercise in the whole spectrum of chronic kidney disease: a systematic review	Barcellos	99	14
	2	The intestine and the kidneys: a bad marriage can be hazardous	Vanholder	60	9
	3	Lymphatic disorders after renal transplantation: new insights for an old complication	Ranghino	57	8
	4	Real-time ultrasound-guided percutaneous renal biopsy with needle guide by nephrologists decreases post-biopsy complications	Prasad	55	8
	4	Nephrology care prior to end-stage renal disease and outcomes among new ESRD patients in the USA	Gillespie	55	8
	5	Pathophysiological role of different tubular epithelial cell death modes in acute kidney injury	Sancho-Martinez	54	8
2016	1	Iohexol plasma clearance for measuring glomerular filtration rate in clinical practice and research: a review. Part 1: How to measure glomerular filtration rate with iohexol?	Delanaye	96	16
	2	Chronic kidney disease in children	Becherucci	83	14
	3	The global nephrology workforce: emerging threats and potential solutions!	Sharif	76	13
	4	Chronic kidney disease hotspots in developing countries in South Asia	Abraham	74	12
	5	Macrophage in chronic kidney disease	Guiteras	72	12
	6	Iohexol plasma clearance for measuring glomerular filtration rate in clinical practice and research: a review. Part 2: Why to measure glomerular filtration rate with iohexol?	Delanaye	69	12
	7	Severe acute interstitial nephritis after combination immune-checkpoint inhibitor therapy for metastatic melanoma	Murakami	64	11
2017	1	2017 update on pain management in patients with chronic kidney disease	Chi Pham	56	11
	1	Urinary peptide-based classifier CKD273: towards clinical application in chronic kidney disease	Pontillo	56	11
	2	Cognitive function and advanced kidney disease: longitudinal trends and impact on decision-making	Iyasere	45	9
	2	Risk factors for bleeding complications after nephrologist-performed native renal biopsy	Lees	45	9
	3	Current evidence on the discontinuation of eculizumab in patients with atypical haemolytic uraemic syndrome	Macia	44	9
	4	Age-dependent reference intervals for estimated and measured glomerular filtration rate	Pottel	39	8
	5	Symptom burden in patients with chronic kidney disease not requiring renal replacement therapy	Brown	38	8
2018	1	The potential for improving cardio-renal outcomes by sodium-glucose co-transporter-2 inhibition in people with chronic kidney disease: a rationale for the EMPA-KIDNEY study	Herrington	110	27.5
	2	Frailty and chronic kidney disease: current evidence and continuing uncertainties	Nixon	63	16
	3	A comparative analysis of survival of patients on dialysis and after kidney transplantation	Kaballo	56	14
	4	Risk factors associated with post-kidney transplant malignancies: an article from the Cancer-Kidney International Network	Sprangers	49	12
	5	Women and kidney disease: reflections on World Kidney Day 2018	Piccoli	45	11
	6	What do epidemiological studies tell us about chronic kidney disease of undetermined cause in Meso-America? A systematic review and meta-analysis	Gonzalez-Quiroz	43	11
2019	1	Renal toxicities associated with pembrolizumab	Izzedine	50	17
	2	Daprodustat for anemia: a 24-week, open-label, randomized controlled trial in participants on hemodialysis	Meadowcroft	48	16
	3	Patterns of medication use and the burden of polypharmacy in patients with chronic kidney disease: the German Chronic Kidney Disease study	Schmidt	41	14
	4	Air pollution and kidney disease: review of current evidence	Afsar	36	12
	5	Daprodustat for anemia: a 24-week, open-label, randomized controlled trial in participants with chronic kidney disease	Holdstock	33	11
	6	Clarifying the concept of chronic kidney disease for non-nephrologists	Perez-Gomez	31	10
2020	1	Characterization of acute kidney injury in critically ill patients with severe coronavirus disease 2019	Rubin	35	17.5
	2	Coronavirus disease 2019 in chronic kidney disease	D'Marco	27	13.5
	3	Anemia and iron deficiency among chronic kidney disease Stages 3–5ND patients in the Chronic Kidney Disease Outcomes and Practice Patterns Study: often unmeasured, variably treated	Wong	25	12.5
	3	Acute kidney injury and kidney replacement therapy in COVID-19: a systematic review and meta-analysis	Fu	25	12.5
	4	The keys to control a COVID-19 outbreak in a haemodialysis unit	Rincon	20	10
2021	1	External validation of prognostic models: what, why, how, when and where?	Ramspek	17	17
	2	Effects of a medium cut-off (Theranova ®) dialyser on haemodialysis patients: a prospective, cross-over study	Cozzolino	15	15
	3	Net ultrafiltration rate and its impact on mortality in patients with acute kidney injury receiving continuous renal replacement therapy	Tehranian	12	12
	4	Acute kidney injury pathology and pathophysiology: a retrospective review	Gaut	11	11
	4	Routinely measuring symptom burden and health-related quality of life in dialysis patients: first results from the Dutch registry of patient-reported outcome measures	van der Willik	11	11
	5	Pathology of COVID-19-associated acute kidney injury	Sharma	7	7
	5	Kidney transplantation and COVID-19 renal and patient prognosis	Toapanta	7	7
	6	Tryptophan levels associate with incident cardiovascular disease in chronic kidney disease	Konje	5	5
	6	Renin–angiotensin system blockade in the COVID-19 pandemic	Cohen	5	5
	6	Tumor necrosis factor-alpha blockade ameliorates diabetic nephropathy in rats	Cheng	5	5
	6	Serum total indoxyl sulfate and clinical outcomes in hemodialysis patients: results from the Japan Dialysis Outcomes and Practice Patterns Study	Yamamoto	5	5
	6	Risk prediction of COVID-19 incidence and mortality in a large multi-national hemodialysis cohort: implications for management of the pandemic in outpatient hemodialysis settings	Haarhaus	5	5
	6	Development and internal validation of a prediction model for hospital-acquired acute kidney injury	Martin-Cleary	5	5
	6	Cellular origin and microRNA profiles of circulating extracellular vesicles in different stages of diabetic nephropathy	Uil	5	5
	6	Health claims databases used for kidney research around the world	Van Oosten	5	5

Source: Reference number [4].

Overall, the most cited manuscripts had chronic kidney disease (CKD) as topic, either non-dialysis or dialysis CKD (Figure 2), followed by onconephrology, cardionephrology, glomerular disease and transplantation. In line with a recent bibliographical analysis, acute kidney injury (AKI) was remarkably underrepresented, except for the coronavirus disease 2019 (COVID-19) context in more recent years [61]. Tables 3 and 4 provide a greater granularity as well as the emergence of topics that have become more relevant in recent years (Table 5). Thus, assessment of CKD by either improving glomerular filtration rate (GFR) assessment by using iohexol to measure GFR or novel methods for assessment of kidney injury, such as the urinary peptidomics biomarker CKD273, were highly cited topics [7, 11]. Regarding onconephrology, the nephrotoxicity of novel anticancer agents also attracted the attention of readers [12, 31, 34]. More recently, novel therapeutic approaches for CKD or its complications, such as sodium-glucose transport protein 2 (SGLT2) inhibitors or hypoxia-inducible factor (HIF) stabilizers, were also topics of interest [5, 39], as well as several manuscripts dealing with the interaction between COVID-19 and kidney disease [38, 40, 44, 47, 56, 57, 59]. COVID-19-related highly cited manuscripts dealt with characterization of AKI in patients with severe COVID-19 and kidney replacement therapy in this context, COVID-19 in CKD and the key role that collective transport to and from hemodialysis units played in the spread of the disease among hemodialysis patients [38, 40, 44, 47]. Finally, topics at the top of the global agenda, such as the impact of air pollution on health and, specifically, on kidney disease have also been highly cited [41]. A special mention should be devoted to the concept of CKD hotspots, first formulated in CKJ as consisting of countries, regions, communities or ethnicities with higher-than-average incidence of CKD [10, 48, 49]. The ERA Registry, discussed below, regularly identifies CKD hotspots in Europe at both the national level (e.g. Portugal, Greece, Cyprus, Kosovo, Israel and North Macedonia) and regional level (e.g. French-speaking Belgium, Canary Islands and the Mediterranean regions of Spain: Catalonia, Valencia and Murcia) [62].

Table 5.

Topics of most highly cited manuscripts published in CKJ in each year between 2014 and October 2021

2014 Onconephrology (nephrotoxicity of anticancer agents) and cardiovascular disease (anticoagulation)

2015 CKD: Exercise and CKD

2016 CKD: Measured GFR

2017 CKD: Urinary peptidomics and pain

2018 CKD: SGLT2 inhibitors

2019 Onconephrology (checkpoint inhibitors) and CKD (HIF stabilizers)

2020 COVID-19

2021 CKD (haemodialysis: medium cut-off dialyser), AKI and COVID-19

Extracted from Table 4.

Source: Reference number [4].

CKJ AND THE ERA REGISTRY

CKJ publishes the summary of the ERA Registry Annual Report. This is one of the most cited items in the journal and was not included in the above analyses. It represents the longest running multinational registry that is searchable as a publication in PubMed. In recent years, Registry Reports have consistently ranked among the top 10 cited items per year, often on the top spot. Furthermore, their citation record has increased over the years [62-69]. The most cited Registry Report was the 2015 report published in 2018 [69]. That year, World Kidney Day was devoted to women and kidney disease, and the ERA Registry was a solid source of information on the epidemiology, treatment and outcomes of kidney replacement therapy in men and women [70, 71].

THE PERSONS WHO MADE IT POSSIBLE

High-quality journals do not just happen. We should be grateful to the authors who considered CKJ to disseminate their expertise and research as well as the reviewers who devoted their time to constructively criticize and improve the quality of the manuscripts (Supplementary data, Tables S1–S8). Finally, a hard-working and expert editorial board liaised with reviewers and integrated their concerns to select the highest quality manuscripts that would be most informative and useful to our readership (Supplementary data, Table S9). A big thank you to all of you and good luck to our new Editor-in-Chief!

CONFLICT OF INTEREST STATEMENT

A.O. has received consultancy or speaker fees or travel support from Advicciene, Astellas, AstraZeneca, Amicus, Amgen, Fresenius Medical Care, Bayer, Sanofi-Genzyme, Menarini, Kyowa Kirin, Alexion, Idorsia, Chiesi, Otsuka, Novo-Nordisk and Vifor Fresenius Medical Care Renal Pharma, and is Director of the Catedra Mundipharma-UAM of diabetic kidney disease and the Catedra Astrazeneca-UAM of chronic kidney disease and electrolytes. A.O. is the Editor-in-Chief of CKJ.

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