Chief Executive Northwest Washington Region, Providence Health and Services

Dissertation Title

A comparative multiyear assessment of care utilization between existing and newly enrolled Medicaid populations within Washington State

Dissertation Abstract

The study looks at 2012 through June of 2016 Medicaid data from the Washington State Health Care Authority, comparing claims utilization for newly enrolled patients each calendar year to continuously enrolled members. Mean number of emergency department, hospital, and ambulatory (office) claims per Medicaid member are compared to ascertain if they are the same or different between the groups. Differences in the mean number of ambulatory care sensitive conditions (ACSC) were additionally assessed between those continuously and newly enrolled. The results of this study provided an early baseline indication of utilization differences for the expansion population in Washington State to see if those newly enrolled are utilizing care differently than those continuously enrolled.

For all categories, mean claims using t-test comparisons for those continuously enrolled versus newly enrolled were significantly different at the (p<.001) level, with the exception of ACSC in the first half year of 2016 and hospice claims in years 2013 and 2016. A linear regression analysis on claims and ACSC counts was performed. The independent variables of new enrollee, age, sex, program type and race were utilized for the analysis. The regression indicated that there was a collectively significant effect (p<.001) of those independent variables on the emergency department, inpatient, and ambulatory (office) claims as well for ACSC in the inpatient and emergency department (ED). The new enrollee coefficient remains statistically significant even after covariate adjustment (p<.001), and direction is consistent (negative coefficient, new enrollees lower) in all regressions except for ACSC inpatient in 2016, which was not significant.

The study found that, on average, those newly enrolled have utilized services to a lesser degree in the ED and ambulatory (office) settings, but more in the inpatient setting. New members also have lower mean counts of ACSC in both the ED and inpatient setting.