Apple Watch wasn’t the first smartwatch, or even the first health-related one. Fitbit and Jawbone pioneered the fitness tracker market and new start-ups are pushing the ball forward on hardware. Oura, for instance, packs a lot of health-related sensors into a simple ring. But none of those companies have Apple’s massive install base of loyal customers. Apple Watches outsell the entire Swiss watch industry, according to a Strategy Analytics report.

Six years in, Apple Watches can detect signs of atrial fibrillation, a potentially deadly heart disorder. But that detection isn’t 100 percent accurate. False positives can send patients to the doctor unnecessarily. It may take a decade or more before the watch has the kinds of sensors and hardcore research necessary to be a health solution for customers, said Gene Munster, an analyst with Loup Ventures, a venture capital firm, making the watch as a health device a long-term bet. “I don’t think they’re close to being there. I think the current watch is limited in what it’s picking up on,” he said.

In the meantime, Apple is earning “credibility in the industry,” according to Tom Dorsett, CEO of RazorMetrics, a health technology company aimed at lowering prescription drug costs. Apple gained FDA clearance for its atrial fibrillation algorithm and its electrocardiogram. “If they’re investing in FDA approval, they’re looking to be something more than a novelty device,” he says.

Apple’s first watch, announced in 2014 and released the following April, came with the introduction of ResearchKit, open-source software that allows medical researchers to find subjects for their studies. Using the software, academic institutions and pharmaceutical companies can enroll Apple’s customers in clinical trials, collecting data on Apple Watches to learn more about the human body.