How Does Risk Selection Respond to Risk Adjustment? New Evidence from the Medicare Advantage Program
研究了2004年Medicare对私人医疗保险优势计划实施风险调整后，计划如何通过招募高分但成本低于预测的个体来增加超额支付，且未发现净超额支付减少的证据。
To combat adverse selection, governments increasingly base payments to health plans and providers on enrollees' scores from risk-adjustment formulae. In 2004, Medicare began to risk-adjust capitation payments to private Medicare Advantage (MA) plans to reduce selection-driven overpayments. But because the variance of medical costs increases with the predicted mean, incentivizing enrollment of individuals with higher scores can increase the scope for enrolling “overpriced” individuals with costs significantly below the formula's prediction. Indeed, after risk adjustment, MA plans enrolled individuals with higher scores but lower costs conditional on their score. We find no evidence that overpayments were on net reduced.