Medicaid enrollment among elderly medicare beneficiaries: individual determinants, effects of state policy, and impact on service use.

<bold>Objective: </bold>To better understand factors associated with Medicaid enrollment among low-income, community-dwelling elderly persons and to examine the effect of Medicaid enrollment on the use of health care services by elderly persons, taking into account selection in program participation.<bold>Data Sources: </bold>1996 Medicare Current Beneficiary Survey (MCBS) Access to Care and Cost and Use files.<bold>Methods: </bold>Individual-level predictions of the probability of dual enrollment are obtained from equations that estimate jointly the residential status of Medicare beneficiaries (community versus institution) and the probability of Medicaid enrollment among community-dwelling eligible beneficiaries. Predicted values are then substituted into the service use equations, which are estimated via two-part models.<bold>Principal Findings: </bold>Less than half of all community-dwelling elderly persons with incomes at or below 100 percent of the Federal Poverty Level (FPL) were enrolled in Medicaid in 1996. Once selective enrollment was accounted for, there was limited evidence of a dual enrollment effect on service use. Although there were no effects of state Medicaid policy variables on the probability that beneficiaries lived in the community (as opposed to nursing homes), the effects of state's Medicaid generosity in home and community-based services had a sizeable and statistically significant effect on influencing the likelihood that eligible elderly persons enrolled in Medicaid.<bold>Conclusions: </bold>Our results provide compelling evidence that Medicaid participation can be influenced by state policy. The observation that "policy matters" provides new insights into how existing programs might reach a larger proportion of potentially eligible beneficiaries. [ABSTRACT FROM AUTHOR]