Introduction: Low back pain (LBP) is a highly prevalent and disabling condition worldwide. LBP risk factors are multifactorial, yet determinants of spine degenerative changes and phenotypes on MRI remain debatable. Lumbar spine fusion is a common spine surgical procedures. In efforts to optimize patient care, great emphasis has been placed in understanding what causes spine degeneration and in identifying factors contributing to negative surgical outcomes, such as early-onset adjacent segment degeneration/disease (EO-ASD). Blood group antigens have previously been linked to numerous vascular, infectious, autoimmune, and musculoskeletal disease processes; however, its implications in lumbar spine health are unknown. As such, the purpose of this study was to explore relationships of blood type with postoperative EO-ASD of the lumbar spine following fusion surgery as well as evaluate differences in spinopelvic alignment, perioperative care, postoperative complications, and patient-reported outcome measures (PROMs).
Methods: An ambispective study was performed. Patients who underwent posterolateral or posterior lumbar interbody fusion were included. Demographic, perioperative and postoperative, clinical, and blood type information was recorded. Pre- and post-operative radiographic imaging was analyzed for alignment parameters and development of EO-ASD.
Results: 445 patients were included, representing O+ (36.0%), O- (5.2%), A+ (36.2%), A- (6.3%), B+ (12.1%), B- (1.6%), and AB+ (2.7%) blood types. Most patients were female (59.1%), and had a mean age of 60.3 years and BMI of 31.1 kg/m2. Postoperatively, groups did not differ in duration of the hospital (p=0.732) or intensive care unit (p=0.830) stay, discharge disposition (p=0.504), reoperation rate (p=0.192), or in-hospital complication rate (p=0.377). Postoperative epidural hematoma was most common amongst A+ patients (p=0.024). Over a mean of 11.0 months of follow-up, all patients exhibited similar improvement in PROMs, with 132 (29.7%) patients developing radiographic evidence of EO-ASD. B+ patients were significantly more likely than A+ and O+ patients to develop spondylolisthesis and EO-ASD (p<0.05). No significant differences in sagittal alignment parameters and number of levels of fusion were found (p>0.05).
Discussion: This large-scale study is the first, to our knowledge, to address and demonstrate proof-of-principle that blood type, a non-modifiable risk factor, is associated with EO-ASD. Specifically, B+ blood type was associated with increased risk for EO-ASD, particularly relative to O+ and A+ types. As a non-modifiable risk factor, “blood type” therefore warrants careful attention in efforts to understand the spine degenerative process and mechanisms, and to develop more precision-based spine care that may assist in predictive modeling. Considering previous studies have associated blood group antigens with unique systemic inflammatory cytokine profiles implicated in musculoskeletal disease progression and pain, it is plausible that blood type may drive lumbar degenerative processes via similar pathophysiology. Nonetheless, further research is needed to validate our findings.