As Medicare Cost plans disappear next year across much of Minnesota, more than 300,000 people in the state find themselves shopping for new coverage this fall in the midst of a national debate.

Is it a good thing that more seniors are getting their government benefits via Medicare Advantage plans from private health insurers?

Or, would people be better off with the traditional Medicare program, which consumers often supplement with Medigap and Part D drug coverage from private insurers?

As with too many things in health care, the answer is complex.

Researchers at the California-based Kaiser Family Foundation published an overview article Wednesday in the New England Journal of Medicine that outlines many of the issues. This year, 66 percent of Medicare beneficiaries are covered by original Medicare versus 34 percent in Medicare Advantage (MA) plans.

"Still to be determined is how the growing role of private insurance in Medicare, and the diminishing role of traditional Medicare, is likely to affect beneficiaries' out-of-pocket spending, satisfaction and health outcomes over time," the researchers concluded.

MA plans limit enrollees out-of-pocket costs per year (at $5,215 this year), whereas original Medicare covers most but not all costs for health care services (leaving 20 percent in some cases).

Advantage plans usually include an integrated prescription drug benefit, and typically offer extra benefits such as help with dental and vision care costs.

The health plans typically use rules for "prior authorization" and "utilization management techniques" to control service use and spending, while also promoting preventive care and care coordination in hopes of better quality and efficiency.

MA plans generally have lower premiums -- including $0 premium plans -- than the combined premium with Medigap and Part D plans that supplement original Medicare. But with MA plans, enrollees often find they must pay more if they get care from a doctor or hospital that's not included in the health plan's network of health care providers.

This "in-network" factor adds complexity, since the size and make-up of networks varies across the different health insurers that sell MA coverage.

"The open provider network of traditional Medicare is important to beneficiaries who value having a broad choice of physicians and other providers," the Kaiser researchers wrote. "Traditional Medicare also allows beneficiaries to get care without the hassles and obstacles that can result from prior authorization and referral requirements frequently used by Medicare Advantage plans."

"In addition, for some beneficiaries with high health care spending, traditional Medicare coupled with supplemental insurance has the potential to be a lower-cost alternative to Medicare Advantage," they wrote.

So, when it's all said and done, which is the higher-quality option?

"Taken together, the evidence on quality may tilt somewhat favorably but not unequivocally toward Medicare Advantage plans, but with limited data, uneven performances across plans and very little information about the experiences and outcomes of patients with complex care needs," the researchers wrote.