No abstract

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We study insurers' use of prescription drug formularies to screen consumers in the ACA Health Insurance Exchanges. We begin by showing that Exchange risk adjustment and reinsurance succeed in neutralizing selection incentives for most, but not all, consumer types. A minority of consumers, identifiable by demand for particular classes of prescription drugs, are predictably unprofitable. We then show that contract features relating to these drugs are distorted in a manner consistent with multi-dimensional screening. The empirical findings support a long theoretical literature examining how insurance contracts offered in equilibrium can fail to optimally trade-off risk protection and moral hazard.

For a detailed description of the data and methods, including issues of representativeness and weighting,

We study insurers’ use of prescription drug formularies to screen consumers in the ACA Health Insurance exchanges. We begin by showing that exchange risk adjustment and reinsurance succeed in neutralizing selection incentives for most, but not all, consumer types. A minority of consumers, identifiable by demand for particular classes of prescription drugs, are predictably unprofitable. We then show that contract features relating to these drugs are distorted in a manner consistent with multidimensional screening. The empirical findings support a long theoretical literature examining how insurance contracts offered in equilibrium can fail to optimally trade off risk protection and moral hazard. (JEL D82, G22, H51, I13, I18)

NBER working papers are circulated for discussion and comment purposes. They have not been peerreviewed or been subject to the review by the NBER Board of Directors that accompanies official NBER publications.

No abstract

Insurance is typically viewed as a mechanism for transferring resources from good to bad states. However, insurance may also transfer resources from high-liquidity periods to low-liquidity periods. We test for this type of transfer from health insurance by studying the distribution of Social Security checks among Medicare recipients. When Social Security checks are distributed, prescription fills increase by 6–12 percent among recipients who pay small copayments. We find no such pattern among recipients who face no copayments. The results demonstrate that more complete insurance allows recipients to consume healthcare when they need it rather than only when they have cash. (JEL D82, G22, H55, I13, I18, L65)