Preparing for Bundled Payments in Cervical Spine Surgery

Do We Understand the Influence of Patient, Hospital, and Procedural Factors on the Cost and Length of Stay?

Piyush Kalakoti, MD; Yubo Gao, PhD; Nathan R. Hendrickson, MD; Andrew J. Pugely, MD


Spine. 2019;44(5):334-345. 

In This Article

Abstract and Introduction


Study Design: Retrospective, observational study.

Objective: To examine the influence of patient, hospital, and procedural characteristics on hospital costs and length hospital of stay (LOS).

Summary of Background Data: Successful bundled payment agreements require management of financial risk. Participating institutions must understand potential cost input before entering into these episodes-of-care payment contracts. Elective anterior cervical discectomy and fusion (ACDF) has become a popular target for early bundles given its frequency and predictability.

Methods: A national discharge database was queried to identify adult patients undergoing elective ACDF. Using generalized linear models, the impact of each patient, hospital, and procedures characteristic on hospitalization costs and the LOS was estimated.

Results: In 2011, 134,088 patients underwent ACDF in the United States. Of these 31.6% had no comorbidities, whereas 18.7% had three or more. The most common conditions included hypertension (44.4%), renal disease (15.9%), and depression (14.7%). Mean hospital costs after ACDF was $18,622 and mean hospital LOS was 1.7 days. With incremental comorbidities, both hospital costs and LOS increased. Both marginal costs and LOS rose with inpatient death (+$17,181, +2.0 days), patients with recent weight loss (+$8351, +1.24 days), metastatic cancer (+$6129 +0.80 days), electrolyte disturbances (+$4175 +0.8 days), pulmonary-circulatory disorders (+$4065, +0.6 days), and coagulopathies (+$3467, +0.58 days). Costs and LOS were highest with the following procedures: addition of a posterior fusion/instrumentation ($+11,189, +0.9 days), revision anterior surgery (+$3465, +0.3 days), and fusion of more than three levels (+$3251, +0.2 days). Patients treated in the West had the highest costs (+$9300, +0.3 days). All P values were less than 0.05.

Conclusion: Hospital costs and LOS after ACDF rise with increasing patient comorbidities. Stakeholders entering into bundled payments should be aware of that certain patient, hospital, and procedure characteristics will consume greater resources.

Level of Evidence: 3


Anterior cervical discectomy and fusion (ACDF) is a routinely performed procedure for cervical spine pathology refractory to conservative treatments. National statistics reveals that more than 130,000 ACDFs are performed annually and these numbers are anticipated to rise in the coming years.[1] This rise is partly attributed to the technical and operative advances including improved implant quality, enhanced bone grafting options, minimally invasive approaches, intraoperative monitoring, neuronavigation, and ability to perform surgery in ambulatory settings. Despite variability in spine care and associated costs,[2] the cumulative 90-day Medicare reimbursements for one- to two-level ACDFs averaged at $15,417, lower compared to reimbursements for total knee replacement ($17,451).[3] Reflecting professional and facility costs, these estimates are often debated to adequately cover cost of care, questioning future economic sustainability. Amidst the recent healthcare reforms directed at cost containment including replacement of the fee-for-service with bundled payments, it is critical to identify patient- and hospital-level factors affecting resource utilization.

Several studies explored comparative effectiveness of ACDF on outcomes across ambulatory and inpatient settings,[4–9] whereas others compared outcomes across ACDF and cervical disc arthroplasty.[10–12] However, limited literature exists evaluating risk factors associated with length of hospital stay (LOS) and costs following ACDF. Single-institutional studies identifying factors associated with longer LOS after ACDF have limited power for generalization, and plagued by inherent selection bias.[13,14] An investigation using the American College of Surgeons' National Surgical Quality Improvement Program registry identified elderly age group (≥65 yr), perioperative complications, increased intraoperative duration, and comorbidities including diabetes and anemia associated with longer LOS after ACDF,[15] underscoring the importance of patient-level comorbidities on outcomes. In context to hospital costs after ACDF, impact of patient-specific factors is less understood; albeit can plausibly aid in identifying modifiable targets that could aid in optimizing the episode bundle.

In the current study, we explore the influence of patient-level demographics, comorbidities, and hospital characteristics on resource utilization and LOS after ACDF surgery using an administrative database. We hypothesize that quantification of such estimates impacting resource use and LOS can be used in optimizing bundled payments in cervical spine surgery.