Risk adjustment cannot solve all selection issues—network contracting edition

In our Hamilton Project paper, Nicholas Bagley, Amitabh Chandra, and I explain why a health insurance market in which plans compete on cost effectiveness won’t work. (Click through, download the PDF, and read Box 2 on page 9, titled “Why Health Plans Cannot Differentiate on Coverage.”)

The recent NBER paper by Mark Shepard makes the same argument we made, but to illustrate problems in hospital markets with heterogeneous preferences for costly, star hospitals. Some key quotes from Mark’s paper:

But even excellent risk adjustment is unlikely to offset costs arising from preferences for using star (or other expensive) providers. These preferences create residual cost variation that can lead to a breakdown of risk adjustment (Glazer and McGuire 2000). Second, the two channels may have different cost and welfare implications. While sickness makes individuals costly in any plan, preferences for a star hospital only make enrollees costly if a plan covers that star hospital. Stated differently, preferences affect how much an individual’s costs increase when their plan adds coverage of the star hospital. […]

My results suggest that consumer preferences for high-cost treatment options – star hospitals in my study, but the same idea could apply to any expensive provider, drug, or treatment – can naturally lead to adverse selection, and specifically selection on moral hazard. […]

In the current system, consumers get access to star hospitals based on their plan choice, after which use of these providers is highly subsidized by the insurer. This setup leads to higher costs (moral hazard) and selection on moral hazard. Policies that reduce this moral hazard – e.g., higher “tiered” copays for expensive hospitals or incentives for doctors to refer patients more efficiently – may also mitigate the adverse selection. Differential plan prices for different groups may also improve the efficiency of consumer sorting across plans.

Mark’s paper is also noteworthy because it is one of the few to address consequences of network contracting. This is a hard area to study because plans’ hospitals and physician networks are not easily observed. Other good work in this area has been done by my colleagues at the Leonard Davis Institute.


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