If you notice inaccuracies or discrepancies (often less than 15 mmHg) in your blood pressure measurements, especially when compared to another device, these are normal fluctuations and it does not necessarily mean that your device is defective.
A measurement difference of less than 15 mmHg between two devices or two readings is often due to your body's natural variation. Rest assured: your device has successfully passed the most demanding clinical validation tests to provide you with reliable medical monitoring.
Blood Pressure: Data that changes constantly
The first factor to consider is not the device, but your own physiology. Your blood pressure is not a straight line; it varies constantly depending on your breathing, your emotions, the time of day, the season, and other phenomena explained later in this article. Blood pressure can vary by 10 to 20 mmHg in just a few minutes.
This is a physiological phenomenon recognized by leading medical authorities, such as the European Society of Hypertension (ESH). In their official directives (2024 Guidelines), they recommend never relying on a single measurement, but rather taking an average to smooth out these natural variations.
What is Clinical Validation?
To guarantee the accuracy of our measurements despite these physiological and environmental variations, clinical validation studies have been performed on Withings blood pressure monitors according to the ISO 81060-2 standard. This standard specifies the requirements and methods for the clinical investigation of non-invasive, automated blood pressure monitors.
Our devices undergo a clinical validation process, ensuring measurement performance equivalent to that of medical-grade equipment.
Clinical data confirms that measurement deviation remains below the tolerance thresholds defined by the international standard ISO 81060-2:2018. This compliance demonstrates the accuracy and reliability of our blood pressure monitors in accordance with global regulatory requirements.
Comparing two measuring devices
If the BPM Connect is clinically validated, why doesn't it give exactly the same value as your old monitor?
- Instantaneous Variability: As explained above, your blood pressure likely changed between measurement A and measurement B.
- The "White Coat Effect": It is common to have higher blood pressure at the doctor's office (due to unconscious stress) than at home in a calm environment. The ESH recognizes that this gap often exceeds 20 mmHg.
- Methodology: Each brand uses a slightly different algorithm. Two devices that both meet the requirements of the standard may use methods where one slightly overestimates the value while the other slightly underestimates it, creating the impression of a significant gap.
How to ensure your measurements are correct?
Please find our key recommendations for accurate measurements below: (Link to guidelines)
- Rest for 5 minutes in a seated position before starting.
- Maintain proper posture: sit with your back straight, feet flat on the floor, and your arm supported so the cuff is at heart level.
- Stay still and remain silent during the measurement to ensure sensor accuracy.
- BPx3 Precision: We recommend taking 3 consecutive readings. The average of these measurements provides the most reliable medical data.