Alterations in 90-Day Morbidity, Mortality and Readmission Rates Following Spine Surgery in Medicare Accountable Care Organizations (2009-2014)

Introduction: Within surgical care afforded by Accountable Care Organizations (ACOs), savings are thought to be realized by improved care coordination as well as reductions in the use of preference sensitive procedures such as lumbar arthrodesis. We sought to investigate this using national Medicare claims data, comparing patients enrolled in Medicare ACOs to those treated in non-ACOs.

Methods: We queried fee-for-service claims for patients enrolled in Medicare during the period 2009–2014, identifying those who received lumbar spine arthrodesis, discectomy or decompression procedures. The raw rate of lumbar arthrodesis was calculated as the number of these procedures divided by the total number of spine surgeries performed. Multivariable logistic regression was used to adjust for socio-demographic and clinical confounders and compare the likelihood of receiving a lumbar arthrodesis in ACOs and non-ACOs in the period before and after ACO formation.

Results: Within organizations that would form ACOs, the raw rate of lumbar arthrodesis increased from 50% (n=2,183) in 2009-2011 to 54% (n=2,283) in 2012-2014. Among non-ACOs, the use of arthrodesis increased from 52% (n=110,160) to 59% (n=109,917). The likelihood of receiving a lumbar spine arthrodesis was significantly greater among non-ACOs in 2012-2014 when compared to organizations that would form ACOs (OR 1.38; 95% CI 1.06, 1.78) as well as actual ACOs in the same time-period (OR 1.19; 95% CI 1.00, 1.42).

Conclusion: Our results indicate that ACOs may effectively curtail the use of lumbar arthrodesis procedures. As these interventions are often associated with higher complications and need for reoperation, such practices might accrue additional healthcare savings for Medicare beyond those realized during the index surgical period.