Upcoding: Evidence from Medicare on Squishy Risk Adjustment
研究发现私人Medicare计划中的患者诊断风险评分比按服务收费的Medicare高出6%至16%，表明存在编码升级行为，导致数十亿超额公共支出并扭曲企业和消费者行为。
In most US health insurance markets, plans face strong incentives to "upcode" the patient diagnoses they report to the regulator, as these affect the risk-adjusted payments plans receive. We show that enrollees in private Medicare plans generate 6% to 16% higher diagnosis-based risk scores than they would under fee-for-service Medicare, where diagnoses do not affect most provider payments. Our estimates imply that upcoding generates billions in excess public spending and significant distortions to firm and consumer behavior. We show that coding intensity increases with vertical integration, suggesting a principal-agent problem faced by insurers, who desire more intense coding from the providers with whom they contract.