You can get an Apple Watch for $49 but there is a catch

Last year, Apple's Heart Study found that the Apple Watch could accurately detect atrial fibrillation (the most common type of irregular heartbeat). This study explored the role of wearable devices in identifying potential heart problems. According to the American Heart Association, atrial fibrillation increases the risk of stroke almost five times.

Johnson and Johnson has now said that it is going to partner with Apple for a study that will use an iPhone app and the Apple Watch to observe how earlier detection of atrial fibrillation impacts stroke in people who are 65 or older.

The joint effort between Apple and Johnson and Johnson (J&J) is called "Heartline" and it aims to study 150,000 participants with long-term follow-ups over two years. The study will also try to reach a different age-group of participants as compared to the set studied by Apple in its original heart study.

The Apple and Johnson and Johnson study will be open to more than 40 million people who are enrolled in traditional healthcare plans. These plans cover people who are 65 and older and even include the disabled. People participating in the study will be randomly assigned to either use only the Heartline iPhone app or use the app along with the Apple Watch that can take an EKG.

If you are assigned to use the app and the watch you can borrow the Apple Watch it free of charge for the duration of the study or you can buy it for $49.

The latest model of the Apple Watch is available for $399 right now and Apple and Johnson and Johnson are going to share the costs to subsidise the watches for the study participants.

The study will also pay participants, "who must agree to share their Medicare claims data". Apple and Johnson and Johnson officials said "that was key to proving whether the use of the app and watch lead to reduced stroke risk".

Apple COO, Jeff Williams said that initial studies have proved that the Apple Watch can detect atrial fibrillation with "low rate of false alarms" which helped the company get clearance from the US Food and Drug Administration for a watch app that takes an electrocardiogram, or EKG, measurement.

The new study with Johnson and Johnson will look into see if early detection leads to better health outcomes.

"We want to follow the science all the way to the end, no matter what the outcomes are, and run this longitudinal study. It's not something that we have to do, but it's the right thing to do," Williams told Reuters in an interview.

In the earlier study, Apple had 400,000 participants but "faced questions from medical experts because more than half of the people who signed up were under 40". This under-40 group is already at low-risk for atrial fibrillation.

Paul Burton, vice president of medical affairs at the J&J subsidiary running the study, said 70 per cent of patients experiencing the condition are over 65.

"What we're trying to do here is definitively answer that question: If you take wearable technology and couple it with an app, can you reduce the risk of a stroke or death?" Burton said.

"With tens of millions of watches on people's wrists and us delivering this early detection, we have a huge responsibility to make sure that early detection is effective and really helping people with their health in the long haul," Apple's Williams told Reuters.