Johnson & Johnson is making one of the biggest bets in the healthcare industry on using data science and artificial intelligence to bolster its work. The 137-year-old pharmaceutical and medical-device company has hired 6,000 data scientists and digital specialists in recent years, and spent hundreds of millions of dollars on their work, such as using machines to scour massive health-record datasets. Last year the company opened a state-of-the-art research site near San Francisco that houses advanced data science. Some early efforts focus on diagnostics, like an algorithm that analyzes heart tests to spot a deadly type of high blood pressure...