A longitudinal evaluation of the effect of medi-cal managed care on supplemental security income and aid to families with dependent children enrollees in two California counties

OBJECTIVE. We examined the differential effect of Medicaid managed care (MM C) among Aid to Families With Dependent Children (AFDC) and Supplemental Se curity Income (SSI) enrollees over time by comparing the experiences of adu lt nonelderly enrollees in the Health Plan of San Mateo in California versu s Ventura County's fee-for-service (FFS) enrollees. RESEARCH DESIGN. Four years of administrative claims data were used to cons truct a longitudinal data set and estimate panel data models to decompose t he effect of managed care over time. RESULTS. AFDC MMC enrollees exhibited generally fewer ambulatory visits, lo wer expenditures, and higher monthly probabilities of a preventable hospita lization relative to comparably enrolled FFS patients. SSI MMC enrollees ha d more emergency department visits and higher monthly probabilities of hosp italization. However, SSI MMC enrollees had more ambulatory visits and more medications during the first year of enrollment relative to SSI FFS enroll ees, although levels were similar in subsequent years. SSI MMC enrollees di d not exhibit a significantly higher level of expenditures in the first yea r of enrollment, although in subsequent years, expenditure levels were sign ificantly lower. CONCLUSIONS. The results for emergency department visits and preventable ho spitalizations presented a decidedly downbeat picture of access to care for AFDC and SSI enrollees in MMC. However, some aspects of utilization under managed care exhibited results consistent with long-term-oriented treatment for enrollees with a greater likelihood of remaining in the system for a l onger period of time (SSI enrollees). By contrast, enrollees more likely to be enrolled for shorter periods (AFDC enrollees) tended to exhibit care pa tterns under MMC consistent with lower levels of care relative to FFS.