News & Commentary

Two studies of MA network size paint two very different pictures


Peter Wehrwein

Medicare beneficiaries are flocking to Medicare Advantage for many reasons, some of which may have to do with the plans being overpaid. Regardless, one of the presumed drawbacks of casting your Medicare lot with an MA plan is that you will have fewer physicians to choose from (and therefore lack access to desirable ones). A 2017 Kaiser Family Foundation report confirmed that presumption. The Kaiser researchers found that roughly a third (35%) of Medicare beneficiaries were in MA plans with narrow networks, which for this and other studies is defined as a plan that includes less than 30% of the physicians in a county.

A study published in the April 2019 issue of Health Affairs painted a drastically different picture of MA plan networks—one that upends the prevailing wisdom. Yevgeniy Feyman, a Boston University School of Public Health PhD student, and his colleagues found that over 80% of MA plans had broad networks and less than 2%, narrow ones.

What accounts for the difference? In a word, methodology. The Kaiser researchers depended on provider directories and a database of physicians to ascertain network size. But provider directories are notoriously inaccurate, so Feyman and his colleagues ingeniously inferred plan networks by looking at prescribing patterns. If an MA plan member had gotten at least one prescription from a physician, that physician was considered to be part of that plan’s network. Their thinking was that plan members wouldn’t be getting prescriptions from out-of-network doctors so a doctor having written a prescription for an MA plan member is a reliable indicator for being in a plan’s network.

Another big difference is that the Kaiser study included all physicians while Feyman et al. included just primary care physicians, although when the Kaiser researchers broke out the figures for primary care physicians, their results were much the same as those for all physicians.

Feyman was diplomatic when we spoke with him: “I think our approach sheds light on narrow networks in a different way.” By depending on provider directories, the Kaiser researchers were taking an approach that is based on what MA plan members experience when they look for a physician, he noted. His group’s approach may be useful for regulators and policy­makers because they can “get to what is actually under the hood.”

Feyman also cautioned against characterizing narrow networks as a bad deal for MA members (“we can’t make normative statements”). Some of his future research will look at whether narrow networks are offset by, say, lower premiums and copays.

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