Feasibility of Telemonitoring Blood Pressure in Patients With Kidney Disease (Oxford Heart and Renal Protection Study-1): Observational Study.
Warner BE., Velardo C., Salvi D., Lafferty K., Crosbie S., Herrington WG., Haynes R.
BACKGROUND: Blood pressure (BP) is a key modifiable risk factor for patients with CKD, with current guidelines recommending strict control to reduce the risk of both progression of CKD and cardiovascular disease. Trials of BP lowering require multiple visits to achieve target BP which increases the costs of such trials, and in routine care BP measured in clinic may not accurately reflect usual BP. OBJECTIVE: We sought to assess whether a telemonitoring system for BP (using a Bluetooth-enable BP machine which could transmit BP measurements to a tablet device which had a bespoke app to guide measurement of BP and collect questionnaire data) was acceptable to patients with CKD, and whether patients would provide sufficient BP readings to assess variability and guide treatment. METHODS: 25 participants with CKD were trained to use the telemonitoring equipment, asked to record BP daily for 30 days, attend a study visit, and then record BP on alternate days for the next 60 days. They were also offered a wrist-worn applanation tonometry device (BPro) which measures BP every 15 minutes over a 24 hour period.Participants were given questionnaires at the one-month and three-month time points, derived from the System Usability Scale and Technology Acceptance Model. All eligible participants completed the study. RESULTS: Mean age was 58 (SD 11) years and mean eGFR was 36 (SD 13) mL/min/1.73m2. 13 out of 25 (52%) participants provided >90% of expected data and 18 out of 25 (72%) provided >80% expected data. The usability of the telemonitoring system was rated highly with mean scores of 84.9/100 (SE 2.8) after 30 days and 84.2/100 (SE 4.1) after 90 days. The coefficient of variation (CV) for variability of telemonitoring systolic BP was 9.4% (95% confidence interval [CI] 7.8 to 10.9), compared to 7.9% (95% CI 6.4-9.5) for the BPro device (P=0.05) (and 9.0% over one year in a recently completed trial with identical eligibility criteria), indicating that most variation in BP is short-term. CONCLUSIONS: Telemonitoring is acceptable to patients with CKD and provides sufficient data to inform titration of antihypertensive therapies in either a randomized trial setting (comparing different targets BPs) or routine clinical practice. Such methods could be employed in both scenarios and reduce costs currently associated with such activities.Registration ISRCTN13725286.