HYDROchlorothiazide versus placebo to PROTECT polycystic kidney disease patients and improve their quality of life: study protocol and rationale for the HYDRO-PROTECT randomized controlled trial.

"Declarations Ethics approval and consent to participateInstitutional Review Board approval was obtained to conduct the clinical trial in the participating countries. This trial will be conducted in accordance with the International Conference of Harmonization Good Clinical Practice Guidelines and will adhere to the ethical principles that have their origin in the Declaration of Helsinki. Informed consent is obtained by the local principal investigator or a delegated member of the study team. Collection and use of biological material and data for ancillary studies require additional (optional) consent provisions. All participants have the right to withdraw at any time during the study. Important protocol modifications are communicated to all relevant parties, including investigators, IRBs, trial participants, regulators, and trial registries. The model consent form is available as Supplementary material. Consent for publicationNot applicable Competing interestsEM received consultancy fees from Otsuka and research funding from Sanofi and the Dutch Kidney Foundation. RG received consultancy fees and/or research grants from Astra-Zeneca, Bayer, Boehringer-Ingelheim, Galapagos, Ipsen, Mironid, Otsuka, and Sanofi. All money was paid to the institution. AP received research funding and lecture fees from Otsuka. The other authors declare that they have no competing interests. Competing interests EM received consultancy fees from Otsuka and research funding from Sanofi and the Dutch Kidney Foundation. RG received consultancy fees and/or research grants from Astra-Zeneca, Bayer, Boehringer-Ingelheim, Galapagos, Ipsen, Mironid, Otsuka, and Sanofi. All money was paid to the institution. AP received research funding and lecture fees from Otsuka. The other authors declare that they have no competing interests."

"Funding This study is funded by a grant from ZonMw (the Netherlands Organisation for Health Research and Development) and from Otsuka Global. ZonMw is an independent Dutch organization that funds health research, and Otsuka Global is a company that produces tolvaptan. Neither funding party has any role in developing the study protocol, the conduct of the trial, or the publishing process."

"Availability of data and materials: The dataset obtained during the current study is available to the members of the steering committee and will be available from the corresponding author upon reasonable request. The results of this trial will be published. Once available, the results of this trial will be available from ClinicalTrials.gov under NCT05373264 and will be submitted to the Clinical Trials Information System (CTIS). A summary of the trial results for laypersons will also be submitted in CTIS. The Universal Trial Number for this study is U1111-1283-3529. The SPIRIT 2013 checklist is provided as Supplementary material.: Data storage and confidentiality: All participant information and the subject code list are securely stored at the participating study sites in locked file cabinets with limited access. Only pseudonymized data is entered in the electronic case report form (eCRF) within the secure web application “REDCap.” Investigators of the specific participating centers are given access only to their own study participants in this web application. The eCRF includes range checks for data values to promote data quality. Biobanked samples will be shipped to the UMC Groningen at the end of the study in pseudonymized form."