Medicaid and CHIP Premiums and Access to Care: A Systematic Review.

BACKGROUND: Premiums are required in Medicaid and the Children's Health Insurance Program in many states. Effects of premiums are raised in policy debates. OBJECTIVE: Our objective was to review effects of premiums on children's coverage and access. DATA SOURCES: PubMed was used to search academic literature from 1995 to 2014. STUDY SELECTION: Two reviewers initially screened studies by using abstracts and titles, and 1 additional reviewer screened proposed studies. Included studies focused on publicly insured children, evaluated premium changes in at least 1 state/local program, and used longitudinal or repeated cross-sectional data with pre/postchange measures. DATA EXTRACTION: We identified 263 studies of which 17 met inclusion criteria. RESULTS: Four studies examined population-level coverage effects by using national survey data, 11 studies examined trends in disenrollment and reenrollment by using administrative data, and 2 studies measured additional outcomes. No eligible studies evaluated health status effects. Increases in premiums were associated with increased disenrollment rates in 7 studies that permitted comparison. Larger premium increases and stringent enforcement tended to have larger effects on disenrollment. At a population level, premiums reduce public insurance enrollment and may increase the uninsured rate for lower-income children. Little is known about effects of premiums on spending or access to care, but 1 study reveals premiums are unlikely to yield substantial revenue. LIMITATIONS: Effect sizes were difficult to compare across studies with administrative data. CONCLUSIONS: Public insurance premiums often increase disenrollment from public insurance and may have unintended consequences on overall coverage for low-income children.