iPhone App compared with standard blood pressure measurement -The iPARR trial.

BACKGROUND: The possibility to use built-in smartphone-cameras for photoplethysmographic (PPG) recording of pulse waves lead to the release of numerous health apps, claiming to measure blood pressure (BP) based on PPG signals. Even though these apps are highly popular, not a single one is clinically validated. Aim of the current study was to test systolic BP (sBP) estimation by a promising new algorithm in a large clinical setting. METHODS: The study was designed based on the European Society of Hypertension International Protocol Revision 2010. Each individual received 7 sequential BP measurements, starting with the reference device - an automated oscillometric cuff device - followed by the PPG recording at the patients' index finger. RESULTS: A total 1,036 subjects were recruited of which 965 could be included for final analysis leading to 2,895 pairs of comparison. Mean (±SD) error between test and reference device was -0.41 (±16.52) mmHg. Only 38.1% of all 2,895 BP comparisons reached a delta within ±5 mmHg, while 29.3% reached a delta larger than 15 mmHg. Bland-Altman plot showed an overestimation of smartphone sBP in comparison to reference sBP in low range and an underestimation in high sBP range. CONCLUSIONS: According to the European Society of Hypertension International Protocol Revision 2010 specifications the algorithm failed validation criteria for sBP measurement and was not commercialized. These findings emphasize that health apps should be rigorously validated according to common guidelines before market release as under- and/or overestimation of BP is potentially exposing persons at health risks in short and long term. TRIAL REGISTRATION: ClinicalTrials.gov, number NCT02552030.

Impact of Single-Occasion American vs. Canadian Office Blood Pressure Measurement Recommendations on Blood Pressure Classification.

BACKGROUND: The 2017 American hypertension guidelines [American College of Cardiology/American Heart Association (ACC/AHA)] define a blood pressure measurement (BPM) procedure that differs from the Canadian Hypertension Education Program (CHEP) guidelines. We studied the impact of the BPM procedure on arterial hypertension (AHT) prevalence rate. METHODS: In 805 subjects, the mean of the first and second BPM (adapted ACC/AHA procedure) was compared with the mean of the second and third BPM (CHEP procedure). All BPMs were taken at a single occasion. According to ACC/AHA definition, office blood pressure (OBP) of <120/80 mm Hg was classified as normal, 120-129/<80 mm Hg as elevated, and ≥130/80 mm Hg as hypertensive. RESULTS: Using the adapted ACC/AHA BPM procedure compared to the CHEP BPM procedure led to an increase in the AHT prevalence rate (≥130/80 mm Hg) of 4% (58% vs. 54%). Overall, 8.9% (72/805) of subjects were reclassified to a higher and 2.6% (21/805) to a lower blood pressure category when using the adapted ACC/AHA BPM procedure instead of the CHEP BPM procedure. In the group with elevated OBP (120-129/<80 mm Hg), 41.9% (36/86) of subjects were reclassified. CONCLUSIONS: Minimal changes of BPM procedures lead to relevant changes of hypertension prevalence. CLINICAL TRIALS REGISTRATION: Trial Number NCT02552030.

Performance of a Blood Pressure Smartphone App in Pregnant Women: The iPARR Trial (iPhone App Compared With Standard RR Measurement).

Hypertensive disorders are one of the leading causes of maternal death worldwide. Several smartphone apps claim to measure blood pressure (BP) using photoplethysmographic signals recorded by smartphone cameras. However, no single app has been validated for this use to date. We aimed to validate a new, promising smartphone algorithm. In this subgroup analysis of the iPARR trial (iPhone App Compared With Standard RR Measurement), we tested the Preventicus BP smartphone algorithm on 32 pregnant women. The trial was conducted based on the European Society of Hypertension International Protocol revision 2010 for validation of BP measuring devices in adults. Each individual received 7 sequential BP measurements starting with the reference device (Omron-HBP-1300) and followed by the smartphone measurement, resulting in 96 BP comparisons. Validation requirements of the European Society of Hypertension International Protocol revision 2010 were not fulfilled. Mean (±SD) systolic BP disagreement between the test and reference devices was 5.0 (±14.5) mm Hg. The number of absolute differences between test and reference device within 5, 10, and 15 mm Hg was 31, 53, and 64 of 96, respectively. A Bland-Altman plot showed an overestimation of smartphone-determined systolic BP in comparison with reference systolic BP in low range but an underestimation in medium-range BP. The Preventicus BP smartphone algorithm failed the accuracy criteria for estimating BP in pregnant women and was thus not commercialized. Pregnant women should be discouraged from using BP smartphone apps, unless there are algorithms specifically validated according to common protocols. CLINICAL TRIAL REGISTRATION: URL: https://www.clinicaltrials.gov. Unique identifier: NCT02552030.

Reliability of single office blood pressure measurements.

OBJECTIVES: Standard operating procedures for office blood pressure measurement (OBPM) vary greatly between guidelines and studies. We aimed to compare the difference between a single OBPM and the mean of the three following measurements. Further, we studied how many patients with possible hypertension may be missed due to short-term masked hypertension (STMH) and how many might be overdiagnosed due to short-term white coat hypertension (STWCH). DESIGN AND SETTING: In this cross-sectional, single-centre trial, 1000 adult subjects were enrolled. After 5 min of rest, four sequential standard OBPMs were performed at 2 min intervals in a quiet room in sitting position. We compared the first (fBPM) to the mean of the second to fourth measurement (mBPM). STMH was defined as fBPM <140 mm Hg systolic and <90 mm Hg diastolic and mBPM systolic ≥140 mm Hg or diastolic ≥90 mm Hg. STWCH was defined as fBPM systolic ≥140 mm Hg or diastolic ≥90 mm Hg and mBPM <140 mm Hg systolic and <90 mm Hg diastolic. RESULTS: Complete measurements were available in 802 subjects. Between fBPM and mBPM, 662 (82.5%), 441 (55%) and 208 (25.9%) subjects showed a difference in systolic and 531 (66.2%), 247 (30.8%) and 51 (6.4%) in diastolic blood pressure (BP) values of >2 mm Hg, >5 mm Hg and >10 mm Hg, respectively. In 3.4% of initially normotensives STMH and in 34.3% of initially hypertensives, STWCH was apparent. CONCLUSIONS: There are significant differences between a single OBPM and the mean of consecutive BP measurements. Our study provides evidence that a single OBPM should not be the preferred method and should be discouraged in future guidelines. TRIAL REGISTRATION NUMBER: NCT02552030;Results.