Variation in Coding Practices for Vestibular Schwannoma Surgery

Background Nationwide databases are a frequently used resource for assessing practice patterns and clinical outcomes. However, analyses based on billing codes may be limited by the inconsistent application of CPT codes to specific operations. We investigated the variability among commonly used CPT codes for resection of vestibular schwannomas and sought to identify factors that underlie this variation.

Methods The surgical procedure for 175 cases of vestibular schwannoma resections performed between 2013 and 2016 at two institutions were reviewed and classified as retrosigmoid, transmastoid retrosigmoid, translabyrinthine, or middle fossa approaches. We then assessed the CPT codes assigned to each case and analyzed the variability in CPT codes based on surgical approach, primary surgeon, and the coding specialty (neurosurgery or otolaryngology). We further assessed the incidence of primary and secondary CPT codes assigned for vestibular schwannoma surgeries in the American College Surgeons National Surgical Quality Improvement Program (ACS-NSQIP) database from 2008 to 2014.

Results Among 175 cases of vestibular schwannoma resections, 129 (74%) were performed using a retrosigmoid approach, 39 (22%) by the translabyrinthine approach, and 7 (4%) by the middle fossa approach. For the retrosigmoid approach, 9 approach codes were observed, with the most common being 61595 (31%) and 61520 (17%); 6 resection codes were documented, with the most common being 61616 (50%). For the translabyrinthine approach, three approach codes and three resection codes were observed, with the most common being 61596 (54%) for approach and 61616 (92%) for resection. For the middle fossa approach, one approach code (61591) and three resection codes were encountered. The assignment of codes for a specific surgical procedure varied significantly based on institution and the surgeon's primary subspecialty. Codes submitted by neurosurgery and otolaryngology for cases performed jointly also revealed differences in coding patterns. In comparison, 20 codes were designated as primary for 720 vestibular schwannoma resections in the ACS-NSQIP database, with the most frequent 5 codes representing 638 (88%) of resections. These included the approach codes 61520 (44% of cases) and 61526 (19%), and the resection code 61616 (12%). A total of 93 codes were included as secondary codes, though only 11 codes were present in greater than 2% of all cases.

Conclusion We observed significant variability in coding patterns for vestibular schwannoma surgeries between institutions and surgical practices. These results call for discretion in interpretation of data from aggregated billing code-based nationwide databases and institutional standardization of CPT assignments for the same approaches.