Premium increases in state health insurance programs: lessons from a case study of the Massachusetts Medicaid buy-in program.

In March 2003, Massachusetts increased the premiums it charges to most enrollees in its CommonHealth-Working (CH-W) program. This study evaluates the impact of the premium change on disenrollment using a comparison group methodology. The findings indicate that the premium change had only a small, but statistically significant impact on program exits. The CH-W experience differs from other state programs that saw substantial enrollment declines in response to new or increased premiums. This is likely due to factors that make CH-W different from other programs, key of which are administrative procedures intended to minimize disenrollment due to premium nonpayment.