Are sagittal spinopelvic radiographic parameters significantly associated with quality of life of adult spinal deformity patients? Multivariate linear regression analyses for pre-operative and short-term post-operative health-related quality of life

To evaluate the association in ASD patients between spinopelvic sagittal parameters and health-related quality of life (HRQL), adjusted for demographic and surgical variables. We constructed multiple linear regression models to investigate pre-operative (PreOp) and 6-month post-operative (PostOp) HRQL as assessed by the Oswestry Disability Index (ODI), with sagittal parameters as independent variables adjusted for potential confounders, such as age, sex, body mass index, past spine surgery, types of surgical treatment, and complications. A total of 204 patients (164 women, 40 men, mean age 53.1 years) were included in this study. In multivariate models for PreOp ODI, no significant association was observed between PreOp HRQL and sagittal parameters when adjusted for covariates. Interestingly, age, sex, American Society of Anesthesiologists score, and body mass index were still significantly associated with PreOp HRQL. In contrast to PreOp analysis, there was a significant association between PostOp worse HRQL (higher ODI) and positive T1 sagittal tilt (T1ST: the angle between a line drawn from the center of the femoral head axis to the midpoint of the T1 vertebral body and a vertical line). Sagittal vertical axis had a weaker association with HRQL than T1ST. PostOp ASD patients lose flexibility in the fused spinal segment, and might be predisposed to symptoms related to spinal sagittal malalignment due to limited compensatory ability to maintain a balanced standing posture. Interestingly, in patients with sagittal imbalance, low pelvic tilt (PT) of < 20 was significantly associated with PostOp worse HRQL; this suggests that lack of pelvic compensatory ability can cause significant disability after ASD surgery. Pre-operatively, the impact of sagittal parameters on HRQL was not as strong as reported in the previous studies that used univariate analysis. Not only sagittal parameters, but also the pre-operative patient's general condition should be carefully reviewed when considering indication for ASD surgery. In contrast, although this is a short-term follow-up study, PostOp HRQL was significantly associated with sagittal parameters. When ASD surgery has been indicated, restoration of spinal sagittal alignment is certainly important for PostOp HRQL.