On this chart, PWV has a very close association with biological age: At the time, I wasn't sure how accurate the reading was -- some things seemed to improve the trend, but it was a very noisy plot. Soon, the FDA required Withings to remove the feature, since it was providing a health diagnostic for free to the public, which they felt should be ordered by a paid physician. After bricking the best feature from the product, they offered a full-refund, which I accepted.
Just a few months ago, a study was published looking at the accuracy for the scale (<10% MAPE):
https://pubmed.ncbi.nlm.nih.gov/32168728/"Home blood pressure monitors are widely used by consumers yet cardiovascular health may be better defined by pulse-wave velocity (PWV)... The Body Cardio scale provides accurate measures of BM and PWV."
Additionally (from the Withings site):
In Europe, this data for improving ones health has been restored to consumers, while in the USA, the data is still restricted. (See Withings: Body Cardio FAQ.)Withings has performed validation studies in collaboration with hospitals (Brigham and Women’s Hospital, Boston / Hôpital Européen Georges Pompidou, Paris / Scripps Institute, San Diego). These studies compared the measurement of the PWV measurement made by Body Cardio to those taken with a medical device used to measure PWV. The results of the studies demonstrate that PWV measurements taken with Body Cardio yielded similar results to measurements taken using the reference medical device.
