The FDA has sent WHOOP, the Boston fitness-band company, a warning letter dated July 14 over Blood Pressure Insights, a feature that gives wearers a daily estimated blood-pressure range on a green-yellow-orange gauge. The agency's position is that estimating blood pressure is not a low-risk wellness function: a falsely low reading could reassure someone with hypertension, and a gauge with color-coded zones implies a diagnosis. WHOOP answered publicly today that it provides a single daily estimate, not a medical measurement, and that the feature is wellness, not medicine. The letter notes that other federal agencies may consider the company's response when awarding contracts. This is the most important document the wearable industry has received in years.
Why this line matters. Consumer wearables live inside a carve-out: software that encourages a healthy lifestyle and is unrelated to diagnosing or treating disease does not need FDA review. Heart rate, steps, sleep scores and recovery numbers all sit inside it. Blood pressure, the FDA is saying, does not, because the number maps directly onto a disease that is a leading modifiable risk factor for heart attack and stroke. The agency is not objecting to the sensor. It is objecting to a number that looks like a diagnosis arriving without the validation a diagnosis requires.
Ben’s takeEvery wearable board is reading this letter tonight. The business model of the category is the wellness carve-out: ship a metric, call it insight, avoid the clinical trial. The moment a metric corresponds to a diagnosis, the carve-out closes and the cost of being in the business goes up by an order of magnitude. Expect two responses — companies that drop the feature, and companies that spend the money to clear it. The second group will be smaller and larger.
Loree’s takeA wrong blood-pressure number is worse than no number. The patient who skips the cuff because the band was green all month is the patient the FDA is describing. I have no objection to a device that nags you toward a real reading. I have a strong objection to one that stands in for it.
Why it matters to a recovering optimizer. The letter draws, in regulatory language, the line this site keeps drawing in plain English: a wellness number is a weather report, and a medical number needs a medical device. The band on your wrist has been letting you blur that line on purpose. The agency just declined to.
If a number on your wrist could change a prescription, it needs a cuff, not a subscription.