Disregard the reported data from the HYGIA project: blood pressure medication not to be routinely dosed at bedtime.

TLDR: The study ‘Bedtime hypertension treatment improves cardiovascular risk reduction: the Hygia Chronotherapy Trial’ should have produced over 150 000 long-term blood pressure measurements with a failure rate of less than 10%; which it cannot achieve in clinical use, not even with Spacelabs devices.

Abstract: W e continuebeing concernedby the study ‘Bedtime hypertension treatment improves cardiovascular risk reduction: the Hygia Chronotherapy Trial’ which was published in the European Heart Journal [1]. The protocol article [2] suggested to us that no properly randomized controlled trial (RCT) with 19 084 participating patients had been performed. The database appears as a summary database of multiple smaller studies already completed and published, such as the MAPEC study [3], which included 2156 hypertensive patients in an identical protocol. There is no evidence that the strict rules that apply to RCTs were followed, no indicationof how the conduct of the study was monitored and no documentation of the membership of the event adjudication committee or of audit by independent investigators. According to the initial protocol (ClinicalTrials.gov NCT00741585) the authors engaged 20 centers but increased to 40 centers and 292 physicians doing yearly 48-h ambulatory blood pressure measurements (ABPM) on 19 000 patients. On this background, only 800 patients dropped out because of inappropriate 48-h measurements; this is impossible if one takes into account the known difficulties when using ABPM devices. Moreover, ABPMs were made with Spacelabs instruments that barely last 48 h in clinical use even when rechargeable batteries were used. Performing 48-h measurements on more than 19 000 patients annually would result in an enormous battery consumption. In total, the HYGIA study should have produced over 150 000 long-term blood pressure (BP) measurements with a failure rate of less than 10%; which we cannot achieve in clinical use, not even with Spacelabs devices.