What is the clinical evidence from this study?

Study design: Observational. Population: Blood pressure monitoring (n=86). Intervention: Aktiia Bracelet vs. Double-blinded auscultation. Primary outcome: Mean difference between Aktiia Bracelet and reference (ISO81060-2 criterion 1) (SBP 0.46 ± 7.75 mmHg, DBP 0.39 ± 6.86 mmHg).

March 4, 2021Open Access

Blood pressure from the optical Aktiia Bracelet: a 1-month validation study using an extended ISO81060-2 protocol adapted for a cuffless wrist device

Q: What does this research mean for the field?

The Aktiia Bracelet satisfies ISO81060-2 validation criteria for blood pressure measurement accuracy over 1 month, with mean differences compared to auscultation of 0.46 ± 7.75 mmHg for SBP and 0.39 ± 6.86 mmHg for DBP. Novelty: ClaimNovelty.METHODOLOGICAL. Consensus alignment: ConsensusAlignment.NEUTRAL.

AVAnna VybornovaSwiss Center for Electronics and Microtechnology (Switzerland)EPErietta PolychronopoulouUniversity of Thessaly AWArlène Wurzner-GhajarzadehUniversity Hospital of Lausanne

Key Result

The Aktiia Bracelet satisfied ISO81060-2 validation criteria over 1 month, with mean differences compared to auscultation of 0.46 ± 7.75 mmHg for SBP and 0.39 ± 6.86 mmHg for DBP.

Study Design

Type

Observational (n=86)

Blinding

Double-blind

Multicenter

Structured PICO

Does the Aktiia Bracelet accurately and precisely measure blood pressure compared to double-blinded auscultation in adults over 1 month?

Population

86 adults aged 21-65 years (mean age 38, 50% female) covering hypotensive to hypertensive blood pressure categories, with varying skin pigmentations and hair follicle densities. Key exclusions: diabetes, tachycardia, atrial fibrillation, renal dysfunction, hyper- or hypothyroidism, upper arm arteriovenous fistula, upper arm amputation.

Intervention

Aktiia Bracelet (noninvasive optical cuffless blood pressure monitor worn at the wrist), initialized once per month using a subject-dependent calibration parameter.

Comparator

Double-blinded auscultation by two trained observers using a validated mercury-free hybrid sphygmomanometer in the standard sitting position.

Outcome

Accuracy and precision of systolic and diastolic blood pressure estimates compared to reference auscultation, assessed via ISO81060-2:2013 criteria 1 (mean and SD of differences) and 2 (SD of averaged paired difference per subject) over 1 month.surrogate

The Aktiia Bracelet, a cuffless optical wrist blood pressure monitor, demonstrated acceptable accuracy and precision over 1 month compared to standard auscultation, satisfying ISO81060-2 criteria in the sitting position.

Main Result

Effect estimate: SBP 0.46 ± 7.75 mmHg, DBP 0.39 ± 6.86 mmHg

Limitations

Did not fulfill the ISO81060-2 requirement of having 20% of readings with SBP ≥ 140 mmHg
Validation was only performed in the sitting position

Abstract

OBJECTIVE: The objective of this study (NCT04027777) was to assess the accuracy and precision of the Aktiia Bracelet, a CE-marked noninvasive optical blood pressure (BP) monitor worn at the wrist, over a period of 1 month. METHODS: In this study, participants aged between 21 and 65 years were recruited. The clinical investigation extended the ISO81060-2:2013 standard to the specificities of cuffless devices. Each BP assessment consisted of the simultaneous recording of optical signals with Aktiia Bracelet and double-blinded auscultation by two trained observers in the standard sitting position. The algorithms of Aktiia Bracelet further processed the recorded optical signals to perform a signal quality check and to calculate uncalibrated estimates of systolic BP (SBP) and diastolic BP (DBP). These estimates were transformed into mmHg using a subject-dependent calibration parameter, which was calculated using the first two available reference measurements per subject. RESULTS: Eighty-six participants were included in the analysis. The mean and SD of the differences between Aktiia Bracelet estimates and the reference (ISO81060-2 criterion 1) were 0.46 ± 7.75 mmHg for SBP and 0.39 ± 6.86 mmHg for DBP. The SD of the averaged paired difference per subject (ISO81060-2 criterion 2) were 3.9 mmHg for SBP and 3.6 mmHg for DBP. CONCLUSION: After initialization and during 1 month, the overall accuracy of Aktiia Bracelet satisfied validation criteria 1 and 2 of ISO81060-2 in the sitting position. The Aktiia Bracelet can be recommended for BP measurement in the adult population.

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