Adams E Kathleen, Herring Bradley
Department of Health Policy & Management, Rollins School of Public Health, Emory University, Atlanta, GA, USA.
Health Serv Res. 2008 Feb;43(1 Pt 2):363-83. doi: 10.1111/j.1475-6773.2007.00763.x.
To use changes in Medicaid health maintenance organization (HMO) penetration across markets over time to test for effects on the extent of Medicaid participation among physicians and to test for differences in the effects of increased use of commercial versus Medicaid-dominant plans within the market.
DATA SOURCES/STUDY SETTING: The nationally representative Community Tracking Study's Physician Survey for three periods (1996-1997, 1998-1999, and 2000-2001) on 29,866 physicians combined with Centers for Medicare and Medicaid Services (CMS) and InterStudy data.
Market-level estimates of Medicaid HMO penetration are used to test for (1) any participation in Medicaid and (2) the degree to which physicians have an "open" (i.e., nonlimited) practice accepting new Medicaid patients. Models account for physician, firm, and local characteristics, Medicaid relative payment levels adjusted for geographic variation in practice costs, and market-level fixed effects.
There is a positive effect of increases in commercial Medicaid HMO penetration on the odds of accepting new Medicaid patients among all physicians, and in particular, among office-based physicians. In contrast, there is no effect, positive or negative, from expanding the penetration of Medicaid-dominant HMO plans within the market. Increases in cost-adjusted Medicaid fees, relative to Medicare levels, were associated with increases in the odds of participation and of physicians having an "open" Medicaid practice. Provider characteristics that consistently lower participation among all physicians include being older, board certified, a U.S. graduate and a solo practitioner.
The effects of Medicaid HMO penetration on physician participation vary by the type of plan. If states are able to attract and retain commercial plans, participation by office-based physicians is likely to increase in a way that opens existing practices to more new Medicaid patients. Other policy variables that affect participation include the presence of a federally qualified health center (FQHC) in the county and cost-adjusted Medicaid fees relative to Medicare.
利用医疗补助健康维护组织（HMO）在不同市场的渗透率随时间的变化，来检验其对医生参与医疗补助程度的影响，并检验市场内商业保险主导型计划与医疗补助主导型计划使用增加所产生的影响差异。
数据来源/研究背景：具有全国代表性的社区追踪研究的医生调查，涵盖三个时期（1996 - 1997年、1998 - 1999年和2000 - 2001年）的29,866名医生，同时结合医疗保险和医疗补助服务中心（CMS）以及InterStudy的数据。
医疗补助HMO渗透率的市场层面估计值用于检验：（1）医生对医疗补助的参与情况；（2）医生开展“开放”（即无限制）业务接纳新医疗补助患者的程度。模型考虑了医生、公司和当地的特征、根据实践成本的地理差异调整后的医疗补助相对支付水平以及市场层面的固定效应。
商业医疗补助HMO渗透率的增加对所有医生，尤其是对门诊医生接纳新医疗补助患者的几率有积极影响。相比之下，在市场内扩大医疗补助主导型HMO计划的渗透率，无论对接纳新患者几率是产生积极还是消极影响，均无效果。相对于医疗保险水平，经成本调整后的医疗补助费用增加，与参与几率以及医生开展“开放”医疗补助业务的几率增加有关。始终降低所有医生参与率的提供者特征包括年龄较大、拥有委员会认证、是美国毕业生以及为个体执业者。
医疗补助HMO渗透率对医生参与的影响因计划类型而异。如果各州能够吸引并留住商业保险计划，门诊医生的参与率可能会以一种方式增加，即让现有业务接纳更多新的医疗补助患者。影响参与率的其他政策变量包括县内是否存在联邦合格健康中心（FQHC）以及相对于医疗保险的经成本调整后的医疗补助费用。
