Appendix A.

Inclusion and exclusion CPT codes

	CPT codes
Stratified by
Pelvic fixation	22848
Included
Standalone PLIF/TLIF	Primary code: 22630; additional level code: 22632
Posterolateral fusion	Primary code: 22612; additional level code: 22614
PLIF/TLIF bundled with posterolateral fusion	Primary code: 22633; additional level code: 22634
Standalone ALIF/LLIF	Primary code: 22558; additional level code: 22585
Excluded
Cervical fusion	22600, 22590, 22551, 22552, 22554
Thoracic fusion	22610, 22556
Non-elective	10140, 11305, 20661, 22010, 22305, 22315, 22326, 22327
Deformity	22800, 22802, 22804, 22806, 22808, 22810, 22812, 22818
Revision	20680, 22830, 22849, 22850, 22852, 22855
Osteotomy	22210, 22212, 22214, 22216, 22220, 22222, 22224, 22226
Intraspinal lesion	63300, 63301, 63304, 63308
Other procedures	22858

Multilevel (≥2-level) fusion was identified by ≥1 entry of additional level code for a specific primary code, or ≥2 entries of separate primary codes with or without their respective additional level codes. Patients who did not meet this criteria were considered to have single level fusion and were excluded. Because thoracic fusion extending into the lumbar spine can be coded for using lumbar CPT codes, we also excluded patients who had >4 additional level codes. ALIF: Anterior lumbar interbody fusion. LLIF: Lateral lumbar interbody fusion. PLIF: Posterior lumbar interbody fusion. TLIF: Transforaminal lumbar interbody fusion.