Analysis of the Distribution of Spending and Risk Factors for High Cost Inpatient Encounters for Anterior Cervical Discectomy and Fusion

From the 2019 HVPAA National Conference

Mr. Andrew Harris (Johns Hopkins Department of Orthopaedic Surgery), Dr. Majd Marrache (Johns Hopkins Department of Orthopaedic Surgery), Dr. Varun Puvanesarajah (Johns Hopkins Department of Orthopaedic Surgery), Ms. Meghana Jami (Johns Hopkins Department of Orthopaedic Surgery), Dr. Amit Jain (Johns Hopkins Department of Orthopaedic Surgery)


Anterior cervical discectomy and fusion (ACDF) surgery is a common elective surgical procedure. In an effort to decrease the cost of ACDF, it is important to understand the cost distribution in high-cost encounters and how they may be related to factors that can be identified preoperatively.


Our primary objective was to determine the difference in cost distribution among high-cost encounters for ACDF. Our secondary objective was to identify preoperative factors that are predictive of having a high-cost encounter.


One to three level ACDF cases from 2015-2018 were reviewed from two medical centers within an academic health system. The total sum of indirect and direct costs related to the encounter was calculated, excluding the cost of surgical implants. High cost encounters were defined as patients with a total cost in the upper 75th percentile. Cost categories were defined as room and board, operating room time, drugs, radiology, laboratory tests, therapy, and other. Logistic regression was used to build a predictive model of having a high-cost encounter based on preoperative demographic and surgical factors. Significance was set at p<0.05.


232 patients were studied, with an average age of 55 ± 11 years. 30% of patients had on-level ACDF, 54% had two-level ACDF, and 36% had three-level ACDF. High-cost encounters had significantly higher absolute costs in all categories – room and board, operative time, drugs, radiology, laboratory tests, therapy and other, p<0.001. High-cost encounters had a higher proportion of costs attributable to room and board (30% vs. 23%, p<0.001), and a lower proportion of costs attributable to radiology (2.9% vs. 3.7%, p=0.009) and operative time (47% vs. 57%, p<0.001). The proportion of cost attributable to drugs, laboratory tests, and therapy were not significantly different, p>0.05. The multivariate model demonstrated significant risk factors for a high cost encounter to be age ≥ 50 years old (OR 2.7, p=0.012), having 3 levels fused (OR 5.2, p<0.001), body mass index ≥ 30 (OR 2.8, p=0.002). Surgeons with ≥ 8 years in clinical practice post-fellowship had decreased odds of having a high-cost encounter (OR 0.31, p=0.010).


Excluding the cost of surgical implants, high-cost encounters for ACDF have a higher proportion of costs related to room and board, indicating that minimizing length of stay may be the most important target for cost-saving interventions. Independent risk factors for high cost encounters include age ≥50 years old, having 3 levels fused, and BMI ≥30. Surgeons with ≥8 years of post-fellowship experience are more likely to have lower cost encounters.

Clinical Implications

Understanding risk factors for high cost ACDF encounters will help clinicians and hospital administrators focus cost-saving efforts appropriately.


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