The Impact of Partial-Year Enrollment on the Accuracy of Risk Adjustment Systems: A Framework and Evidence

Keith Ericson, Kimberley Geissler and Benjamin Lubin

No 23765, NBER Working Papers from National Bureau of Economic Research, Inc

Abstract: Accurate risk adjustment facilitates healthcare market competition. Risk adjustment typically aims to predict annual costs of individuals enrolled in an insurance plan for a full year. However, partial-year enrollment is common and poses a challenge to risk adjustment, since diagnoses are observed with lower probability when individual is observed for a shorter time. Due to missed diagnoses, risk adjustment systems will underpay for partial-year enrollees, as compared to full-year enrollees with similar underlying health status and usage patterns. We derive a new adjustment for partial-year enrollment in which payments are scaled up for partial-year enrollees’ observed diagnoses, which improves upon existing methods. We simulate the role of missed diagnoses using a sample of commercially insured individuals and the 2014 Marketplace risk adjustment algorithm, and find the expected spending of six-month enrollees is underpredicted by 19%. We then examine whether there are systematically different care usage patterns for partial-year enrollees in this data, which can offset or amplify underprediction due to missed diagnoses. Accounting for differential spending patterns of partial-year enrollees does not substantially change the underprediction for six-month enrollees. However, one-month enrollees use systematically less than one-twelfth the care of full-year enrollees, partially offsetting the missed diagnosis effect.

JEL-codes: I11 I13 I18 (search for similar items in EconPapers)
Date: 2017-09
New Economics Papers: this item is included in nep-ias
Note: AG EH
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Citations: View citations in EconPapers (2)

Published as Keith M. Marzilli Ericson & Kimberley H. Geissler & Benjamin Lubin, 2018. "The Impact of Partial-Year Enrollment on the Accuracy of Risk-Adjustment Systems: A Framework and Evidence," American Journal of Health Economics, vol 4(4), pages 454-00000.

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