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 procedure, and in efforts to optimize patient care, great emphasis has been placed on understanding causes of spine degeneration and 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 preoperative degenerative phenotypes and postoperative EO-ASD of the lumbar spine following fusion surgery.

Methods: Prospective data from patients who underwent lumbar spinal fusion at a single institute were reviewed. Demographic, operative, clinical, and blood type information was recorded, and available MRI and radiographic imaging was analyzed. Specifically, MRIs were assessed for presence of black disc, disc space narrowing, disc displacement, high intensity zones, endplate abnormalities, Modic change, osteophytes, spondylolisthesis, and facet joint edema from L1-S1, whereas plain radiographs were examined for signs of EO-ASD adjacent to the index fusion. Univariate and multivariate regression analyses were performed.  

Results: Of the 1,016 patients in the cohort, imaging phenotypes were randomly assessed in 212 patients with preoperative MRI and 445 with pre- and postoperative plain radiographic data.  Baseline demographics did not differ by blood type with the exception that A- patients were older than O+ patients. Significant associations were observed between blood type and endplate abnormalities on preoperative MRI (p=0.012) and postoperative EO-ASD (mean follow-up: 8.78±2.85 months; p=0.038). Relationships persisted in multivariate analyses, as B+ patients were more likely to exhibit endplate abnormalities than O+ (odds ratio [OR]:0.28, 95% confidence interval [CI]:0.09–0.90, p=0.032), A+ (OR:0.24, 95% CI:0.07–0.78, p=0.018), A- (OR:0.22, 95% CI:0.05–0.99, p=0.048), and AB+ (OR:0.06, 95% CI:0.01–0.47, p=0.007) patients. B+ patients were also more likely to develop EO-ASD than O+ (OR:0.24, 95% CI:0.09–0.62, p=0.003) and A+ (OR:0.32, 95% CI:0.13–0.80, p=0.014) patients.

Discussion: This large-scale study is the first, to our knowledge, to address and demonstrate proof-of-principle that blood type is associated with specific lumbar spine degenerative phenotypes and EO-ASD.  Specifically, B+ blood type was associated with increased risk for endplate abnormalities and EO-ASD, particularly relative to O+ and A+ types. Historically, endplate abnormalities have been noted to potentially precede or increase severity of disc degeneration and predispose to EO-ASD. 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.