Time-Driven Activity-Based Costing for Cervical Myelopathy Surgery: A Step Towards Total Episode Costs.

Introduction: Time-driven activity-based costing (TDABC) is a highly accurate method for determining the true cost of delivering a healthcare service. However, TDABC is most often applied to a singular phase of care such as an outpatient visit or a surgical event. Here we broaden the scope by using TDABC to estimate the costs of surgically treating cervical myelopathy - from the moment of surgical scheduling until post-operative hospital discharge.

Methods: In a single-center retrospective study at a large tertiary academic institution, TDABC was employed to measure pre-operative, intra-operative, and post-operative (inpatient) costs for 63 patients undergoing elective surgery for cervical myelopathy. Cost patterns among different surgical approaches (anterior, posterior, anterior/posterior) were analyzed using generalized linear models and the Kruskal-Wallis test.

Results: 63 consecutive patients who underwent elective surgery for cervical myelopathy were examined (anterior approach: 36.5%, n=23; posterior approach: 54.0%, n=34; anterior/posterior approach: 9.5%, n=6). The average pre-operative, intraoperative, and postoperative costs were $352.83 ± $205, $10,809.09 ± $6052.69, and $5327.07 ± $5114.78, respectively. The average total episode cost for all cases was $16,488.99 ± $8,181,777. Kruskal-Wallis analysis revealed that total episode cost for the anterior-posterior approach was significantly higher than for both the anterior (p<0.001) and posterior approaches (p<0.05), while the total episode cost for the anterior approach was significantly less than that of the posterior (p<0.001).

Conclusion: We have demonstrated the feasibility of TDABC for estimating a large fraction of total episode costs for the surgical treatment of cervical myelopathy. This may also be the first attempt at understanding episode costs across multiple surgical options for a given spinal diagnosis, which will be relevant as condition-based bundled payments emerge. As expected, anterior cervical surgeries incurred lower costs than posterior surgeries, which incurred lower costs than anterior-posterior surgeries.