Insurers may be threatening to leave the healthcare marketplace for lack of profits, but they’re drawn to one area of coverage – Medicare Advantage. Enrollment in the program has jumped from 11 million to 17 million since 2010.

Dana Goldman is director of the Schaeffer Center for Health Policy and Economics at the University of Southern California. He said insurers can rely on older patients to need certain things. They’re predictable, and insurers like that.

“That is to say, we know how much seniors are going to spend, we know the kinds of drugs they use,” he said. So it’s easier to budget for this group.

Dan Mendelson of consultancy Avalere Health said this program is incentivized differently, too. Unlike regular fee-for-service Medicare, he said, “the Medicare Advantage plan gets paid more if it immunizes patients, or if it keeps population cholesterol levels low or if gets diabetes under control.”

He said by managing patients’ health, the plan also ends up benefiting seniors, most of whom keep using Medicare Advantage once they’ve signed up.