The Impact of Tort Reform on Employer-Sponsored Health Insurance Premiums
利用1998-2006年美国各州改革时间差异，发现侵权改革使自保型健康计划保费降低2.1%，但对完全保险计划（主要是HMO）无影响，表明HMO本身已减少防御性医疗。
We evaluate the effect of tort reform on employer-sponsored health insurance premiums by exploiting state-level variation in the timing of reforms. Using a dataset of health plans representing over 10 million Americans annually between 1998 and 2006, we find that the most common set of tort reforms during this period reduces premiums of employer-sponsored self-insured health plans by 2.1%. Of the four individual reforms comprising this set, caps on noneconomic damages and collateral source reforms have the greatest impact. We do not find reductions in premiums for fully insured plans, which in our sample are almost entirely Health Maintenance Organizations (HMOs). Further analysis reveals that self-insured HMOs are also unresponsive to reforms. Taken together, these findings suggest that HMOs reduce "defensive medicine, " even absent reform. The results are the first direct evidence that tort reform reduces healthcare costs in aggregate; prior research has largely focused on particular medical conditions. The Author 2010. Published by Oxford University Press on behalf of Yale University. All rights reserved. For Permissions, please email: journals.permissions@oup.com, Oxford University Press.