Stanford Medicine has published the full results from its record-breaking Apple Heart Study. While preliminary results were presented back in March, the full results were published today in the New England Journal of Medicine.

As reported by CNBC, the researchers say that Apple sponsored the study and owns the data, but the study data is stored at Stanford. The Apple Heart Study consisted of over 400,000 participants, all of whom wore an Apple Watch, and ran for eight months. Around one-quarter completed the protocol of wearing a patch to monitor their heart’s rhythm for two weeks before sending it back.

Of the 400,000 participants, just over 2,000 people received a notification from their Apple Watch of irregular heart beat. That equates to around 0.5% of the participants.

Of those who received a notification from their Apple Watch, and returned the aforementioned electrocardiogram patch, 84% of the detections by the Apple Watch were confirmed to be atrial fibrillation. “That indicates that this kind of passive monitoring can be effective, although further studies are needed,” CNBC says.

If you narrow the participant set to those older than 65, over 3% received notifications – corroborating the widely-accepted belief that atrial fibrillation is common in older people.

Other conclusions from the findings noted by CNBC:

Some of the atrial fibrillation detected by the Apple Watch was early stage, meaning that it happened infrequently enough that the subsequent patch did not pick it up. That didn’t necessarily mean, according to the researchers, that there were a lot of false positive results. This was particularly true among the younger participants.

Fewer people returned the patches than anticipated. Only a quarter did so, indicating that getting people to adhere to the monitoring when it was more active (wearing a patch and sending it back, versus just wearing a watch), was a challenge.

The researchers noted repeatedly that they did not intend to prove that the Apple Watch could be a screening tool for health conditions in large populations.

The full results can be found in the New England Journal of Medicine. You can also find great coverage on what the results mean from CNBC.

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