摘要：Objectives. We compared the quality of care received by managed care Medicaid beneficiaries in counties with a choice of health plans and counties with no choice. Methods . This cross-sectional study among California Medicaid beneficiaries was conducted during 2002. We used a multivariate Poisson model to calculate adjusted rates of hospital admissions for ambulatory care–sensitive conditions by duration of plan enrollment. Results. Among beneficiaries with continuous Medicaid coverage, the percentage with 12 months of continuous enrollment in a health plan was significantly lower in counties with a choice of plans than in counties with no choice (79.2% vs 95.2%; P < .001). Annual ambulatory care–sensitive admission rates adjusted for age, gender, and race/ethnicity were significantly higher among beneficiaries living in counties with a choice of plans (6.58 admissions per 1000 beneficiaries; 95% confidence interval [CI] = 6.57, 6.58) than among those in counties with no choice (6.27 per 1000; 95% CI = 6.27, 6.28). Conclusions. Potential benefits of health plan choice may be undermined by transaction costs of delayed enrollment, which may increase the probability of hospitalization for ambulatory care–sensitive conditions. Extending consumer choice in health care is an important policy objective in a growing number of countries, reflecting recent developments in the United Kingdom 1 and the Netherlands. 2 This trend is occurring because choice and associated market-like competition are seen by many as an essential component of strategies to improve quality and efficiency and to increase the responsiveness of health care systems. 3 , 4 Choice and competition are highly embedded features of the financing and delivery of health care in the United States. Many consumers of US health care are afforded a choice of health plans, medical groups, and providers as well as the ability to directly access specialist care and seek a second opinion. During the Clinton era, 5 the concepts of competition and choice became synonymous with, rather than simply enablers of, efficient, high-quality health care. However, concern is increasing among health care analysts that the potential benefits of competition and choice are not being realized in practice. 6 Furthermore, popular concerns about loss of choice have undermined key efforts to reform the US health care system. For example, arguments from those who opposed the expansion of managed care in the 1990s were often framed around how managed delivery systems would restrict choice of doctors and access to care. 7 Similarly, opponents of recent proposals for a government-run, public plan option argued that the public option would limit, rather than expand, health plan choice by undermining the viability of commercial plans. 8 The availability of choice is not uniform across the US health care system, and the poor and uninsured frequently have either no choice or limited choices. For example, Medicaid beneficiaries typically have fewer providers to choose from than do patients with commercial insurance because of low participation rates by physicians in the Medicaid program. 9 , 10 Although approximately 60% of Medicaid beneficiaries nationwide are in managed care, the extent to which beneficiaries are able to choose a health plan varies considerably both between and within states. 11 , 12 In California, managed care is mandatory for Temporary Assistance for Needy Families (TANF) Medicaid beneficiaries in 21 counties where approximately 90% of the state's beneficiaries reside. This group of California Medicaid beneficiaries consists mainly of children (67% are aged 18 years or younger) and younger women (66% of adult beneficiaries are women younger than 50 years). Although California beneficiaries do not have a choice about being in managed care, they may have a choice of health plans, depending on the county in which they reside. California has 3 county models of mandatory managed care: (1) County Organized Health Systems (COHS), with a single, nonprofit, county-run health plan (8 counties); (2) Two Plan counties, in which a nonprofit, county-run plan competes with a commercial plan (11 counties); and (3) Geographic Managed Care, in which multiple commercial plans compete (2 counties). In counties in which TANF beneficiaries have a choice of health plans, the beneficiaries have up to 45 days after gaining Medicaid eligibility to choose a plan. Furthermore, beneficiaries can change plans at any time while they are enrolled in California Medicaid. The difference between counties in the availability of health plan choice provides a natural experiment in which to compare differences in the quality of care delivered to the target population. In the present study, we examined the hypothesis that Medicaid beneficiaries living in counties that offer a choice of health plans receive a higher quality of care and have better health outcomes than do beneficiaries living in counties with a single health plan.
