Home blood pressure monitors owned by participants in a large decentralised clinical trial in hypertension: the Treatment In Morning versus Evening (TIME) study

Various home blood pressure monitors (HBPMs) are available to the public for purchase but only some are validated against standardised protocols. This study aimed to assess whether HBPMs owned by participants taking part in a clinical trial were validated models. The TIME study is a decentralised randomised trial investigating the effect of antihypertensive medication dosing time on cardiovascular outcomes in adults with hypertension. No HBPMs were provided to participants in this trial but patients were asked to report if they already owned one. We identified the model of HBPM reported by participants, then cross-referenced this against lists of validated HBPMs produced by dabl Educational Trust and the British and Irish Hypertension Society (BIHS). Of 21,104 participants, 10,464 (49.6%) reported their model of HBPM. 7464 (71.3%) of these participants owned a monitor that could be identified from the participants' entry. Of these, 6066 (81.3%) participants owned a monitor listed as validated by either dabl (n = 5903) or BIHS (n = 5491). Some were listed as validated by both. 1398 (18.7%) participants owned an identifiable HBPM that lacked clear evidence of validation. 6963 (93.3%) participants owned an upper arm HBPM and 501 (6.7%) owned a wrist HBPM. Validated HBPMs had a higher median online retail price of £45.00 compared to £20.00 for HBPMs lacking clear evidence of validation. A significant number of participants own HBPMs lacking evidence of validation.