|
Article Excerpt
Lack of dental insurance is one of the main barriers affecting access to dental services (U.S. Department of Health and Human Services 2000). In the late 1980s and early 1990s, the U.S. government gradually increased eligibility for public health insurance for low-income children, mainly under the Medicaid program. However, before the recent establishment of the State Children's Health Insurance Program (SCHIP) in 1997, some low-income children lacked health insurance because their family incomes were too high to be eligible for Medicaid but not high enough to afford private health insurance for medical care, let alone dental insurance. Congress created the SCHIP program to further expand public health insurance coverage to uninsured low-income children.
SCHIP has the potential to become a major dental insurer for low-income children. The SCHIP legislation authorized states to expand eligibility for public insurance for uninsured children younger than 19 years of age in families with incomes up to 200 percent of the federal poverty level (FPL), or 50 percentage points above the Medicaid threshold in effect in March 1997, whichever was greater. States had three options for SCHIP program design: expand Medicaid, establish a separate health insurance program, or a combination of the two. States that expanded Medicaid were required to provide full Medicaid benefits (including dental benefits) for SCHIP enrollees. The dental benefits provided in separate SCHIP programs were usually more generous than private dental plans. Although dental benefits are optional for separate SCHIP programs, by 2000 all states except Delaware, Colorado, and Florida offered dental benefits (Kenney, McFeeters, and Yee 2005).
The SCHIP program is also designed to help enroll children eligible for Medicaid through mandated coordination between the two programs in outreach and enrollment. For example, SCHIP applicants must first be screened for Medicaid eligibility, and if found to be eligible for Medicaid, their enrollment facilitated. As a result, Medicaid enrollment--which historically has been low (U.S. Government Accountability Office 2000; Remler and Glied 2003)--has increased since SCHIP implementation (Rosenbach et al. 2003). This effect of SCHIP on Medicaid enrollment is called the spillover effect. Therefore, both SCHIP and Medicaid-eligible children who had not previously enrolled in Medicaid may have obtained public dental coverage because of implementation of SCHIP.
By expanding public health insurance, SCHIP is expected to improve low-income children's access to and use of dental care. However, having public dental insurance does not guarantee access to dental care (Mofidi, Rozier, and King 2002; Mofidi et al. 2002). Medicaid enrollees, who are entitled to comprehensive dental services, often have poor access to dental care, primarily because of a shortage of participating dental providers. One reason for the low level of dentists' participation is low reimbursement rates. A few states used SCHIP to experiment with financing public dental care (Almeida, Hill, and Kenney 2001). For example, North Carolina contracted with Blue Cross Blue Shield to process dental claims. Not only does the program appear more like private insurance to participating dentists, but fees paid to providers were substantially more than for Medicaid. As a result, North Carolina children enrolled in SCHIP were found to have improved dental care access relative to those enrolled in Medicaid (Slifkin, Silberman, and Freeman 2004; Brickhouse, Rozier, and Slade 2006).
SCHIP has increased eligibility for public dental coverage and stimulated the reform of dental care delivery systems. In addition, through its spillover effect, it has helped Medicaid-eligible children enroll in Medicaid and obtain dental insurance. Yet the extent to which SCHIP has improved access to dental care and use of dental services among low-income children is largely unknown, especially at the national level.
A few state-specific studies have looked at separate SCHIP programs only. They find that compared with the pre-enrollment period, newly enrolled SCHIP children were less likely to report experiencing access difficulties and more likely to have seen a dentist within the past 12 months (Lave et al. 1998; Mofidi, Rozier, and King 2002; Mofidi et al. 2002; Damiano et al. 2003; Fox et al. 2003; Szilagyi et al. 2004). One recent national-level study of SCHIP-eligible children with chronic health conditions found that SCHIP expansions decreased the probability of having unmet need for dental care (Davidoff, Kenney, and Dubay 2005). It also found the same effect for children eligible for Medicaid, which indicates SCHIP implementation may have a spillover effect.
Our study analyzes how SCHIP affects dental care access and use at the national level for two subpopulations. The first is low-income children. We investigate the overall effect of SCHIP implementation on outcomes of interest for all low-income children, only some of whom actually enrolled in SCHIP or Medicaid as a result of SCHIP implementation. To examine effects of public program on outcomes of interest for enrolled children, in the second subpopulation we include children who are enrollees of public insurance programs, mainly SCHIP and Medicaid.
We use the same data set, which contains multiple years of national cross-sectional data, but different analytical approaches for the two subpopulations. To identify the effect of SCHIP implementation for low-in-come children, we compare outcomes of interest pre-versus post-SCHIP implementation using variation in SCHIP availability to children within and across states. We estimate the effect of public health insurance enrollment on dental care access and use, using instrumental variables methods to correct for selection bias due to voluntary program enrollment.
METHODS
Data Source and Study Population
This study includes children from the Sample Child Files of the National Health Interview Survey (NHIS) from 1997 to 2002. The NHIS, conducted by the Centers for Disease Control and Prevention's National Center for Health Statistics (NCHS), has continuously collected a variety of health-related information including health insurance, access to and use of health services from nationally representative samples of the U.S. civilian noninstitutionalized population since 1957 (NCHS 2000). The Sample Child Files of NHIS contain information for one child from each family. Each year the Sample Child File consists of about 13,000 children younger than 18 years of age.
We restrict the sample to children with family incomes below state SCHIP eligibility limits. They are likely to be eligible for SCHIP or Medicaid and therefore likely to be affected by SCHIP implementation. We exclude children younger than 2 years of age, whose dental care access and use information are not collected in the survey. We do not use pre-1997 data because the NHIS questionnaire was redesigned in 1997 and many variables are not comparable afterwards. Observations (N=7,664) with missing values for variables used in this study are excluded. The final analysis sample consists of 21,295 low-income children aged 2-17 years.
Measurement of Key Variables
The dependent variables are dichotomous measures of unmet dental care...
|
