BACKGROUND: Diabetic nephropathy (DN) is one of the major late complications of diabetes. Treatment aimed at slowing down the progression of DN is available but methods for early and definitive detection of DN progression are currently lacking. The 'Proteomic prediction and Renin angiotensin aldosterone system Inhibition prevention Of early diabetic nephRopathy In TYpe 2 diabetic patients with normoalbuminuria trial' (PRIORITY) aims to evaluate the early detection of DN in patients with type 2 diabetes (T2D) using a urinary proteome-based classifier (CKD273). METHODS: In this ancillary study of the recently initiated PRIORITY trial we aimed to validate for the first time the CKD273 classifier in a multicentre (9 different institutions providing samples from 165 T2D patients) prospective setting. In addition we also investigated the influence of sample containers, age and gender on the CKD273 classifier. RESULTS: We observed a high consistency of the CKD273 classification scores across the different centres with areas under the curves ranging from 0.95 to 1.00. The classifier was independent of age (range tested 16-89 years) and gender. Furthermore, the use of different urine storage containers did not affect the classification scores. Analysis of the distribution of the individual peptides of the classifier over the nine different centres showed that fragments of blood-derived and extracellular matrix proteins were the most consistently found. CONCLUSION: We provide for the first time validation of this urinary proteome-based classifier in a multicentre prospective setting and show the suitability of the CKD273 classifier to be used in the PRIORITY trial.

2nd Department of Internal Medicine 3rd Faculty of Medicine Charles University Prague Czech Republic

Barbara Davis Center for Childhood Diabetes University of Colorado Denver Aurora CO USA

BHF Glasgow Cardiovascular Research Centre Institute of Cardiovascular and Medical Sciences University of Glasgow Glasgow UK

Charité Universitaetsmedizin Berlin Medizinische Klinik 4 Berlin Germany

Clinical Division of Nephrology Department of Internal Medicine Medical University of Graz Graz Austria

Department of Internal Medicine University Medical Center Groningen and University of Groningen Groningen The Netherlands

Department of Internal Medicine University Medical Center Groningen and University of Groningen Groningen The Netherlands Department of Clinical Pharmacology University Medical Center Groningen Groningen and University of Groningen The Netherlands

Department of Nephrology and KfH Renal Unit Hospital St Georg Leipzig Germany

Department of Nephrology University of Skopje Skopje Macedonia

Diabetes Center 2nd Department of Medicine Athens University Medical School Hippokration Hospital Athens Greece

Diabetes Centre Institute for Clinical and Experimental Medicine Prague Czech Republic

Division of Nephrology University Hospital Zürich Switzerland

Hannover Clinical Trial Center Hannover Germany

HealthPlus Diabetes and Endocrinology Center Abu Dhabi UAE

Human Nutrition and Metabolism Research and Training Center Institute of Molecular Biosciences Karl Franzens University of Graz Graz Austria

IIS Fundacion Jimenez Diaz UAM IRSIN and REDIREN Madrid Spain

Institut für Klinische Chemie Medizinische Hochschule Hannover Hannover Germany

IRCCS Istituto di Ricerche Farmacologiche Mario Negri Clinical Research Center for Rare Diseases 'Aldo e Cele Daccò' Bergamo Italy

IRCCS Istituto di Ricerche Farmacologiche Mario Negri Clinical Research Center for Rare Diseases 'Aldo e Cele Daccò' Bergamo Italy Unit of Nephrology and Dialysis Azienda Ospedaliera Papa Giovanni XXIII Bergamo Italy

Mosaiques Diagnostics GmbH Hanover Germany

Mosaiques Diagnostics GmbH Hanover Germany BHF Glasgow Cardiovascular Research Centre Institute of Cardiovascular and Medical Sciences University of Glasgow Glasgow UK

Mosaiques Diagnostics GmbH Hanover Germany Charité Universitaetsmedizin Berlin Medizinische Klinik 4 Berlin Germany

Mosaiques Diagnostics GmbH Hanover Germany Institut National de la Santé et de la Recherche Médicale U1048 Institut of Cardiovascular and Metabolic Disease Toulouse France Université Toulouse 3 Paul Sabatier Toulouse France

RD Néphrologie Montpellier France

RD Néphrologie Montpellier France Néphrologie Dialyse St Guilhem Sète France Service de Néphrologie Dialyse Péritonéale et Transplantation Montpellier France

Steno Diabetes Center Gentofte Denmark

Steno Diabetes Center Gentofte Denmark HEALTH University of Aarhus Aarhus Denmark Faculty of Health University of Copenhagen Copenhagen Denmark

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Association of kidney fibrosis with urinary peptides: a path towards non-invasive liquid biopsies?

Proteomic prediction and Renin angiotensin aldosterone system Inhibition prevention Of early diabetic nephRopathy in TYpe 2 diabetic patients with normoalbuminuria (PRIORITY): essential study design and rationale of a randomised clinical multicentre trial