Hospital Utilization and Universal Health Insurance Coverage: Evidence from the Massachusetts Health Care Reform Act

The Affordable Care Act is currently in the roll-out phase. To gauge the likely implications of the national policy we analyze how the Massachusetts Health Care Reform Act impacted various hospitalization outcomes in each of the 25 major diagnostic categories (MDC).

We utilize a difference-in-difference approach to identify the impact of the Massachusetts reform on insurance coverage and patient outcomes. This identification is achieved using six years of data from the Nationwide Inpatient Sample from the Healthcare Cost and Utilization Project. We report MDC-specific estimates of the impact of the reform on insurance coverage and type as well as length of stay, number of diagnoses, and number of procedures.

The requirement of universal insurance coverage increased the probability of being covered by insurance. This increase was in part a result of an increase in the probability of being covered by Medicaid. The percentage of admissions covered by private insurance fell. The number of diagnoses rose as a result of the law in the vast majority of diagnostic categories. Our results related to length of stay suggest that looking at aggregate results hides a wealth of information. The most disparate outcomes were pregnancy related. The length of stay for new-born babies and neonates rose dramatically. In aggregate, this increase serves to mute decreases across other diagnoses. Also, the number of procedures fell within the MDCs for pregnancy and child birth and that for new-born babies and neonates.

The Massachusetts Health Care Reform appears to have been effective at increasing insurance take-up rates. These increases may have come at the cost of lower private insurance coverage. The number of diagnoses per admission was increased by the policy across nearly all MDCs. Understanding the changes in length of stay as a result of the Massachusetts reform, and perhaps the Affordable Care Act, requires MDC-specific analysis. It appears that the most important distinction to make is to differentiate care related to new-born babies and neonates from that related to other diagnostic categories.