Factors Associated With Improved Quality of Life Outcomes in Patients Undergoing Surgery for Adult Spinal Deformity

Hideyuki Arima, MD, PhD; Tomohiko Hasegawa, MD, PhD; Yu Yamato, MD, PhD; Daisuke Togawa, MD, PhD; Go Yoshida, MD, PhD; Tatsuya Yasuda, MD, PhD; Tomohiro Banno, MD, PhD; Shin Oe, MD, PhD; Yuki Mihara, MD, PhD; Hiroki Ushirozako, MD, PhD; Tomohiro Yamada, MD; Yuh Watanabe, MD; Koichiro Ide, MD; Keiichi Nakai, MD; Yukihiro Matsuyama, MD, PhD


Spine. 2021;46(6):E384-E391. 

In This Article

Materials and Methods

Patient Population

This study was reviewed and approved by our Institutional Review Board (IRB No. 14–306, Hamamatsu University School of Medicine) and adhered to the principles of the Declaration of Helsinki. We obtained written informed consent from all participants to publish our findings. In this study, patients were diagnosed with ASD if they were 18 years' old or older with confirmed presence of at least one of the following: coronal scoliosis with a Cobb angle ≥20°, a sagittal vertical axis (SVA) ≥5 cm, pelvic tilt (PT) ≥25°, or thoracic kyphosis ≥60°. The cohort included patients with ASD who underwent extensive corrective fixation surgeries between 2010 and 2016 at a single institution. To be included in our cohort, patients had to have received posterior instrumented fusion from the thoracic spine to the pelvis and have available full-length standing radiographs and HRQOL data collected before and 2 years after the operation. Posterior instrumented fusion from the thoracic spine to the pelvis was defined as extensive corrective fusion surgery. Cases of spinal deformities associated with infection, malignancy, and neuromuscular disease were excluded from the study. Patients with incomplete outcome data were excluded. Data on the following patient characteristics were extracted: age, sex, body mass index (BMI) (kg/m2), Charlson Comorbidity Index (CCI),[16] and American Society of Anesthesiologists (ASA) classification. The pathology of the patient was investigated. We defined scoliosis that started during teen years and progressed to adulthood as adult scoliosis. We defined kyphoscoliosis or kyphosis that developed during adulthood and that caused by the degeneration of spinal structures as adult degenerative kyphoscoliosis or degenerative kyphosis scoliosis. HRQOL data were derived from the SRS 22r-Score domains (function/activity, pain, self-image/appearance, mental status, satisfaction, and subtotal score).[12,17]

Radiographic Measurements

Full-length freestanding posteroanterior and lateral spine radiographs obtained before and 2 years after surgery were analyzed. Seven board-certified spine surgeons used standard techniques to measure spinopelvic parameters, including: thoracic kyphosis (TK; Cobb angle between the superior endplate of T-5 and inferior endplate of T-12), lumbar lordosis (LL; Cobb angle between the superior endplate of L-1 and superior endplate of S-1), PT (angle subtended by a vertical reference line originating from the center of the femoral head and the midpoint of the sacral endplate), mismatch between pelvic incidence (PI; angle between the line perpendicular to the sacral plate at its midpoint and the line connecting this point to the femoral head axis), and SVA (C-7 plumb line relative to S-1).[18,19] The interobserver correlation coefficient for TK, LL, PT, PI, SS, and SVA was 0.751, 0.736, 0.882, 0.744, 0.730, and 0.837, respectively.[20]

Patient-reported Outcome Measures

The SRS-22r is a scoliosis specific HRQOL questionnaire with 22 items and five domains: Function, Pain, Self-image, Mental Health, and Satisfaction.[12] Each domain score ranges from 1 to 5 points, with higher scores indicating better outcomes.[17,21,22] The scale has been reported as representative, reliable, and valid in populations with ASD.[9–11] We calculated the mean improvement rate as follows: 100 × (postoperative value – preoperative value)/preoperative value for SRS-22r each domain.

MCID Threshold Value

MCID for the SRS-22r for ASD has been previously reported based on data from a Japanese cohort; these values were: Function = 0.90, Pain = 0.85, Self-image = 1.05, Mental Health = 0.70, and Subtotal = 1.05.[14,23] The rate of achievement of MCID for SRS-22r Function, Pain, Self-image, Mental health, and Subtotal domain 2 years after surgery was calculated.[24]

Statistical Analyses

All values are expressed as mean ± standard deviation (SD). The Shapiro-Wilk test was used to verify the assumption regarding the normal distribution of the data. A paired sample t test and Wilcoxon signed-rank test were used for within-group comparisons of continuous variables. For each SRS-22r domain, MCID achievement was used as an objective variable, and age, sex, BMI, CCI, preoperative SRS-22r, pre- and post-operative spinopelvic parameters, the number of fused segments, and presence or absence of revision surgery were used as explanatory variables. Logistic regression analysis was used to calculate odds ratios (OR) and corresponding (95% confidence intervals (95% CIs) for the MCID of each SRS-22r domain. Preoperative SRS-22r domain scores were dichotomized according to the best cutoff value established from a receiver-operating-characteristic (ROC) curve analysis. An ROC curve was constructed for each domain. The optimal cutoff value for ROC corresponds to the point of optimal trade-off between sensitivity and specificity. The ROC curve derived the cutoff value for the preoperative SRS-22r domain score with equal weight to both sensitivity and specificity to distinguish the "MCID achievement for each domain" from the "no MCID achievement" patients. The accuracy of the ROC curve was evaluated using the calculated area under the curve (AUC). A P value <0.05 was considered statistically significant. Statistical analyses were performed using the Statistical Package for Social Sciences (SPSS) software (version 26.0; SPSS, Chicago, IL).