ACOs Not Linked to Improved Lumbar Spine Surgery Outcomes

2018 Outstanding Paper Award Winner

Peer Reviewed

Patients who underwent lumbar spine surgery at Accountable Care Organizations (ACOs) did not have improved 90-day post-surgical outcomes (morbidity, mortality, and readmission) compared with patients who underwent lumbar spine surgery at non-ACOs, according to a retrospective review of Medicare claims data published in the January issue of The Spine Journal. The study was named 2018 Outstanding Paper Award Winner: Surgical Science by The Spine Journal and the North American Spine Society.
Man with a walker, getting out of a hospital bed.According to study findings, patients who underwent lumbar spine surgery at ACOs did not have improved 90-day post-surgical outcomes. Photo Source: rawpixel on Unsplash.The implications from this study are that “meaningful changes in post-operative outcomes should not be anticipated based on organizational participation in ACOs at present and, were improvements in such outcomes a definite aspiration, mechanisms directed at surgical quality would have to be emphasized in ACO models,” the study authors noted. More specifically, “Contracts would have to stipulate meaningful and measurable changes in quality around surgical care to motivate ACOs to specifically focus on this aspect of healthcare,” lead author Andrew J. Schoenfeld, MD, MSc, told SpineUniverse.

Knowledge Gaps on Impact of ACOs on Post-Operative Outcomes

“ACOs have been heralded as a means to improve quality in healthcare,” explained Dr. Schoenfeld, who is Associate Professor of Orthopaedic Surgery at Brigham and Women’s Hospital, Harvard Medical School, Boston, MA. “While some putative benefits have been shown in certain scenarios, mostly around primary care, it is unclear that much of an impact would be seen in surgery.”

The present study was designed to fill the knowledge gap on the impact of ACOs on post-operative outcomes. Lumbar spine interventions were selected for this paper given the frequency and cost associated with these surgeries, according to the study authors.

“My colleagues and I have had a long-standing interest in evaluating the impact of health reform efforts on the delivery of spinal surgical care,” Dr. Schoenfeld said. “Often, wide ranging initiatives that cover healthcare holistically have unintended ramifications in certain arenas. It is important to understand this for the spine surgical field.”

Retrospective Review of CMS Data From 2009-2014

The researchers examined Center for Medicare and Medicaid Services (CMS) fee-for-service claims for patients who underwent lumbar interbody fusion, posterolateral fusion, decompression, or discectomy procedures between January 1, 2009, and December 31, 2014. Of the 344,813 patients included in this analysis, a small minority (3%) received surgery through an ACO, which were formed after implementation of the Affordable Care Act in 2012. The ACO and non-ACO groups had similar demographics and clinical characteristics.

Organizations that later became ACOs had higher rates of complications and readmissions at baseline. Both ACO and non-ACO groups showed improvements in post-operative outcomes during the period of 2012-2014; however, these improvements were greater in the non-ACO group leading the ACO group to show a significantly greater risk for complications at 90 days (18% increase) and 90-day readmission rate (14% increase) compared to the non-ACO group.

The findings may be generalizable in the United States given that the complication and readmission rates found in this study are similar to those found in large claims-based studies on lumbar spine surgeries, the study authors noted.

Limitations of the Data Set

“It would have been great to have access to more granular data, such as the extent of spinal pathology involved or the rationale for particular approaches from the provider standpoint,” Dr. Schoenfeld said. “This could help understand whether top-down pressure from an ACO/or other healthcare entity was responsible for the results.”


“We did expect to find that, given the design of ACOs and their intent, there would be more meaningful improvement in short-term outcomes following spine surgery,” Dr. Schoenfeld noted.

“We realize that the results presented here represent but a 5-year period that encompasses the ACO implementation stage and substantive health reform efforts engendered by the ACA,” Dr. Schoenfeld and colleagues concluded. “It is entirely possible that as more organizations form ACOs and current ACOs become more adept at improving healthcare quality and efficiency, demonstrable improvements in post-surgical outcomes may follow.”

The study was supported by a grant from CMS.

Dr. Schoenfeld has no relevant financial disclosures.

Updated on: 01/08/19
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What Are the “Critical Elements” of Spine Surgeries?
Andrew J. Schoenfeld, MD, MSc
Associate Professor of Orthopaedic Surgery
Harvard Medical School
Boston, MA

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