Quantity and Reporting Quality of Kidney Research

Abstract

Background: In 2004, researchers reported that the number of nephrology clinical trials was low and that the reporting quality of such trials was suboptimal. Furthermore, the number or quality of preclinical kidney-related studies has not been systematically evaluated.

Methods: We performed a systematic review of randomized clinical trials published in 1966-2017 (listed in the Cochrane Library) and preclinical studies published in 1945-2017 (listed in PubMed). For reporting quality analysis, we evaluated the final main paper of 118 clinical trial reports and 135 preclinical studies published in leading journals in 1996, 2006, and 2016 on the basis of criteria from the widely used CONSORT and ARRIVE guidelines.

Results: The annual number of reports of clinical kidney-related trials more than doubled between 2004 and 2014 along with reports in other medical disciplines. Hypertension remains the dominant focus of study, but ongoing trials also center on CKD, ESRD, and AKI. The reporting quality analysis revealed improvements, but deficits in reporting of clinical trial design, mode of randomization, and intention-to-treat analysis remain. Annual numbers of kidney-related preclinical studies remained low between 1945 and 2017 compared with other disciplines. Reporting quality analysis of preclinical studies revealed substantial reporting deficits across all leading journals, with little improvement over the last 20 years, especially for group size calculations, defining primary versus secondary outcomes, and blinded analysis.

Conclusions: Nephrology studies keep increasing in number but still lag behind other medical disciplines, and the quality of data reporting in kidney research can be further improved.

Keywords: clinical trial; kidney; kidney disease.

Graphical abstract

Figure 1.

Quantitative analysis and topic coverage of clinical trials in medical disciplines identified from the Cochrane database. Several MeSH terms were applied to best cover each discipline as described in Methods. Nephrology (“Kidney”) is represented by the MeSH term “kidney diseases.” Expanded (Exp.) nephrology (“Kidney Exp.”) also covers the MeSH term “RRT” (subterms included “renal dialysis,” “peritoneal dialysis,” and “kidney transplantation”). (A) Annual number of clinical trials per discipline from 1966 to 2016. The sudden decline in numbers in the years 2015–2016 should relate to delays in data inclusion. (B) Disease entities as defined by the available MeSH terms were quantified as described in Methods. Annual number of clinical trials per kidney disease entity from 1966 to 2016. The sudden decline in numbers in the years 2015–2016 should relate to delays in data inclusion. RCT, randomized, controlled trial; MeSH, medical subject heading.

Figure 2.

Quantitative analysis of preclinical studies identified from PubMed. Several MeSH terms were applied to best cover each discipline as described in Methods. Nephrology (“Kidney”) is represented by the MeSH term “kidney diseases.” Expanded (Exp.) nephrology (“Kidney Exp.”) also covers the MeSH term “RRT.” (A) Annual number of preclinical studies per discipline from 1945 to 2016 and (B) topic coverage among the preclinical studies trials of the nephrology domain (B). The sudden decline in numbers in the years 2015–2016 should relate to delays in data inclusion. MeSH, medical subject heading.

Figure 3.

Quality assessment of reporting clinical trials in the main final paper according to the Consolidated Standards of Reporting Trials (CONSORT) criteria reveals improvements with time. Each of the CONSORT criteria was assessed as nonreported, unclear/insufficiently reported, or sufficiently reported in representative samples selected from The New England Journal of Medicine (NEJM), The Lancet (Lancet), Journal of the American Society of Nephrology (JASN), American Journal of Kidney Disease (AJKD), and Kidney International (Kidney Int.) of the years 1996, 2006, and 2016. Shown are the percentages of papers fulfilling the criterion “sufficiently reported” for (A) all journals in each of the 3 years to detect changes over time or (B) each of the journals across all time points. The selected number of papers was too small to also analyze trends over time for each journal.

Figure 4.

Quality assessment of reporting preclinical studies in the main paper according to the Animal Research: Reporting In Vivo Experiments (ARRIVE) criteria does not reveal improvements with time. Each of the ARRIVE criteria (except for title and abstract criteria) was assessed as nonreported, unclear/insufficiently reported, or sufficiently reported in representative samples selected from Journal of the American Society of Nephrology (JASN), Kidney International (Kidney Int.), and Nephrology Dialysis and Transplantation (NDT) of the years 1996, 2006, and 2016. Shown are the percentages of papers fulfilling the criterion “sufficiently reported” for (A) all journals in each of the 3 years to detect changes over time or (B) each of the journals across all time points. The selected number of papers was too small to also analyze trends over time for each journal.