Association of Medicaid expansion under the Affordable Care Act with access to elective spine surgical care

J Neurosurg Spine. 2021 Sep 24;1-9. doi: 10.3171/2021.3.SPINE2122. Online ahead of print.


Objective: The Affordable Care Act expanded Medicaid eligibility in many states, improving access to some forms of elective healthcare in the United States. Whether this effort increased access to elective spine surgical care is unknown. This study's objective was to evaluate the impact of Medicaid expansion under the Affordable Care Act on the volume and payer mix of elective spine surgery in the United States.

Methods: This study evaluated elective spine surgical procedures performed from 2011 to 2016 and included in the all-payer State Inpatient Databases of 10 states that expanded Medicaid access in 2014, as well as 4 states that did not expand Medicaid access. Adult patients aged 18-64 years who underwent elective spine surgery were included. The authors used a quasi-experimental difference-in-difference design to evaluate the impact of Medicaid expansion on hospital procedure volume and payer mix, independent of time-dependent trends. Subgroup analysis was conducted that stratified results according to cervical fusion, thoracolumbar fusion, and noninstrumented surgery.

Results: The authors identified 218,648 surgical procedures performed in 10 Medicaid expansion states and 118,693 procedures performed in 4 nonexpansion states. Medicaid expansion was associated with a 17% (95% CI 2%-35%, p = 0.03) increase in mean hospital spine surgical volume and a 23% (95% CI -0.3% to 52%, p = 0.054) increase in Medicaid volume. Privately insured surgical volumes did not change significantly (incidence rate ratio 1.13, 95% CI -5% to 34%, p = 0.18). The increase in Medicaid volume led to a shift in payer mix, with the proportion of Medicaid patients increasing by 6.0 percentage points (95% CI 4.1-7.0, p < 0.001) and the proportion of private payers decreasing by 6.7 percentage points (95% CI 4.5-8.8, p < 0.001). Although the magnitude of effects varied, these trends were similar across procedure subgroups.

Conclusions: Medicaid expansion under the Affordable Care Act was associated with an economically and statistically significant increase in spine surgery volume and the proportion of surgical patients with Medicaid insurance, indicating improved access to care.

Keywords: Medicaid; Patient Protection and Affordable Care Act; access to healthcare; administrative data research; health service research; spine surgery.