Abstract
Study Design
Retrospective study.
Objective
This study aimed to identify the key determinants of long-term patient satisfaction after adult spinal deformity (ASD) surgery.
Methods
Data of 393 patients who underwent long-segment fusion for ASD were retrospectively analyzed. Patients were classified into the highly satisfied (HS) and less satisfied (LS) groups based on the mean satisfaction scores of the Scoliosis Research Society-22 (SRS-22) questionnaire at the final follow-up. Demographic data, surgical variables, radiographic parameters, mechanical complications, and clinical outcomes were compared between groups. Multivariate logistic regression analysis was used to identify the independent predictors of high satisfaction.
Results
The LS and HS groups comprised 31.0% and 69.0% of the cohort, respectively. The mean follow-up duration was 36.7 months. No significant differences were found in patient demographics, surgical factors, or 6-week radiographic parameters between groups. However, at the final follow-up, the LS group exhibited a significantly greater thoracic kyphosis (P = .038), greater sagittal vertical axis (P = .013) and a higher revision rate (P = .022) than the HS group. All patient-reported outcomes were significantly better in the HS group than in the LS group. Multivariate analysis identified the final SRS-22 self-image score as the only independent predictor of high satisfaction (odds ratio = 6.982, P = .001). The calculated cutoff value of the self-image score for predicting high satisfaction was 3.0.
Conclusion
Self-image perception at the final follow-up was the most significant factor influencing patient satisfaction after ASD surgery. Therefore, global sagittal alignment should be pertinently achieved and maintained to optimize patient satisfaction.
Keywords
Introduction
Adult spinal deformity (ASD) is a complex condition frequently accompanied by sagittal spinal malalignment, leading to functional impairment, chronic low back pain, negative self-image, and psychological distress, all of which collectively impact patients’ quality of life. Previous research have reported the effectiveness of surgical treatment for ASD and its superiority over conservative treatment.1,2 However, some patients experience dissatisfaction with their surgical outcomes. This is likely due to the extensive nature of surgery and the relatively high risk of complication compared with short-level fusion surgery.3,4
Therefore, accurately identifying the factors influencing postoperative satisfaction is imperative for optimizing patient satisfaction. Patient satisfaction after ASD surgery can be influenced by various factors. Preoperative characteristics, such as patient demographics, comorbidities, and baseline disability levels, are known to contribute to postoperative outcomes.5-8 Additionally, adequate radiographic correction of sagittal plane deformities plays a pivotal role in securing short- and long-term surgical outcomes.9-11 However, even if appropriate correction is achieved immediately after surgery, various degrees of loss of correction or sagittal decompensation may occur over the follow-up period,12,13 and mechanical complications may happen, often necessitating revision surgery. These adverse findings can collectively lead to decreased patient satisfaction.10,14 However, regardless of initial deformity correction status, occurrence of mechanical complications, or performance of revision surgery, patient satisfaction can also be independently affected by the final radiographic results or subjective perception of their symptoms at the final follow-up.7-9
Likewise, patient satisfaction can be affected by various factors from the preoperative data to the final follow-up data. Therefore, we sought to identify the most influential factors affecting the final patient satisfaction following ASD surgery. For this, we have analyzed comprehensive datasets including patient factor, surgical variables, radiographic results, mechanical complication development, and clinical outcomes.
Materials and Methods
Study Design and Patient Selection
This study was approved by our institutional review board (IRB no. 2024-07-144). We retrospectively analyzed patient records from a prospective ASD database at our tertiary hospital. Consecutive patients who underwent instrumented fusion for degenerative ASD between 2012 and 2022 were enrolled in this study. Patients were included if the met the following criteria: (1) ASD which was defined as pelvic incidence minus lumbar lordosis (PI-LL) mismatch ≥ 10°, pelvic tilt (PT) ≥ 25°, thoracic kyphosis (TK) ≥ 60°, sagittal vertical axis (SVA) ≥ 5 cm, or a coronal Cobb angle ≥ 30°; (2) ≥ 5-level fusion including the sacrum or pelvis; and (3) a minimum follow-up period of 2 years. Patients were excluded if they had neuromuscular, inflammatory, or other non-degenerative pathological conditions or if they did not complete the minimum follow-up period or had insufficient radiographic or clinical data.
Patient Grouping
Patient satisfaction was assess at the final outpatient visit by using the satisfaction subdomains of Scoliosis Research Society-22 (SRS-22) questionnaire. The satisfaction subdomain included two questions: (1) “Are you satisfied with the results of your back management?” and (2) “Would you have the same management again if you had the same condition?”. Each item was scored from 1 to 5, with higher scores indicating higher satisfaction. The mean score of these two questions was used to categorized patients into the less satisfied (LS group, <4.0) and highly satisfied (HS group, ≥ 4.0) groups, as used in previous studies.9,11,15 Various factors were compared between the LS and HS groups.
Presumed Factors Affecting Patient Satisfaction
We evaluated all presumed factors potentially affecting patient satisfaction with regard to demographic data, surgical variables, radiographic data, mechanical complications, and clinical outcomes. Baseline demographic data included sex, age, American Society of Anesthesiologists (ASA) grade, frailty status using the modified frailty index-5 (mFI-5), 6 body mass index (BMI), T-score (lowest score on spine or hip on bone densitometry), Hounsfield unit at the uppermost instrumented vertebra (UIV), 16 and history of previous lumbar fusion. Surgical variables included approach (anterior-posterior combined vs posterior-only), pedicle subtraction osteotomy (PSO), pelvic fixation, and a total number of fusion levels. The following sagittal parameters were measured preoperatively, at 6 weeks postoperatively, and at the last follow-up: PI-LL, LL, sacral slope (SS), PT, TK, T1 pelvic angle (TPA), and SVA. We also evaluated the development of mechanical complications, such as proximal junctional kyphosis (PJK) and rod fracture (RF). PJK was defined as a proximal junctional angle ≥ 20°. 17 PJK cases were analyzed by separating them into those requiring revision surgery and those that did not. Regarding RF, we included only symptomatic bilateral RFs; thus, asymptomatic unilateral RF was not assigned into mechanical complication group. The performance of revision surgery was analyzed based on the causative etiology, with separate evaluations of PJK and RF. Finally, as the patient-reported outcome measures (PROMs) the Oswestry Disability Index (ODI), and SRS-22 scores were assessed preoperatively and at the last follow-up. The SRS-22 score were evaluated for all four subdomains (function, pain, self-image, and mental health) along with the subtotal score.
Statistical Analysis
Data are presented as numbers with percentages for categorical variables and as means with standard deviations for continuous variables. Repeated-measures analysis of variance was used to compare the sagittal parameters at the three time points: preoperatively, 6 weeks, and at the last follow-up. Kaplan–Meier survival analysis was performed to determine the revision-free survival time. For bivariate analyses, the aforementioned presumed risk factors were compared between the LS and HS groups using the independent t-tests (or Mann–Whitney U test, as appropriate) for continuous variables and the chi-square tests for categorical variables. Stepwise multivariate logistic regression analysis was performed to identify independent influencing factors to predict high satisfaction using variables with statistical significance in bivariate comparisons between the two groups. Receiver operating characteristic (ROC) curve analysis was conducted to calculate the predictability of the identified factors for high satisfaction. Finally, the final sagittal parameters were compared between the groups based on the cutoff value from the ROC curve analysis using the independent t-tests. All statistical analyses were performed using the R (version 4.2.0) and IBM SPSS Statistics for Windows (version 27; IBM Corp., Armonk, NY, USA). Statistical significance was set at P < .05.
Results
Baseline Data
Baseline Data.
Abbrevations: ASA, American Society of Anesthesiologists; mFI-5, modified frailty index-5; BMI, body mass index; UIV, upper instrumented vertebra.
Overall Radiographic Results
Figure 1 presents the comparison of sagittal parameters, including PI-LL, LL, SS, PT, TK, TPA, and SVA, at three time points: preoperatively, 6 weeks postoperatively, at the last follow-up. All sagittal parameters demonstrated significant changes between preoperatively and 6 weeks postoperatively, as well as between 6 weeks postoperatively and the last follow-up, as confirmed by post-hoc analysis using Bonferroni method. However, the magnitude of changes was smaller between 6 weeks postoperatively and the last follow-up than that observed between the preoperative and 6-week postoperative time points. Specifically, the PI-LL mismatch decreased from 36.8° preoperatively to 5.9° at 6 weeks postoperatively but increased to 11.7° at the last follow-up. The PT also significantly decreased from 37.0° preoperatively to 18.0° at 6 weeks postoperatively and slightly increased to 22.7° at the last follow-up. Similarly, the SVA decreased from 74.0 mm preoperatively to 19.8 mm at 6 weeks postoperatively but increased to 34.5 mm at the last follow-up. This results indicate that while significant radiographic improvements were observed at 6 weeks postoperatively, a subsequent loss of correction occurred by the final follow-up. Overall radiographic results across three measurement time points: preoperatively, at 6 weeks, and at the last follow-up. For all sagittal parameters, the differences between each time point were statistically significant (P < .05) by post-hoc analysis with the repeated-measures analysis of variance.
Development of Mechanical Complications
During the mean follow-up period of 36.7 months, 115 patients (29.3%) developed PJK, of whom 30 patients (7.6%) required revision surgery. Thirty (7.6%) patients underwent revision surgery for RF. In total, revision surgery was performed for 54 patients (13.7%). On Kaplan-Meier survival analysis, the median revision-free survival times was 11.3 months (95% confidence interval [CI] = 8.4 – 15.5 months) (Figure 2). Kaplan–Meier survival curve for revision surgery.
Bivariate Comparison of Risk Factors
Comparison of Demographic Data, PROMs, and Surgical Variables Between the Groups.
Abbrevations: ASA, American Society of Anesthesiologists; mFI-5, modified frailty index-5; BMI, body mass index; UIV, upper instrumented vertebra; PROM, patient-reported outcome measures; ODI, Oswestry Disability Index; SRS-22, Scoliosis Research Society-22 questionnaire.
Comparison of Perioperative Sagittal Parameters Between the Groups.
Abbrevations: PI, pelvic incidence; LL, lumbar lordosis; SS, sacral slope; PT, pelvic tilt; TK, thoracic kyphosis; TPA, T1 pelvic angle; SVA, sagittal vertical axis.
Comparison of Data at the Last Follow-Up.
Bold P values indicate statistical significance.
Abbrevations: LS, less satisfied; HS, highly satisfied; PJK, proximal junctional kyphosis; RF, rod fractures; PI, pelvic incidence; LL, lumbar lordosis; SS, sacral slope; PT, pelvic tilt; TK, thoracic kyphosis; TPA, T1 pelvic angle; SVA, sagittal vertical axis; PROM, patient-reported outcome measure; ODI, Oswestry Disability Index; SRS-22, Scoliosis Research Society-22 questionnaire.
Key Determinant for Predicting High Satisfaction
Multivariate Logistic Regression Analysis to Predict High Satisfaction.
Bold P values indicate statistical significance.
Abbrevations: TK, thoracic kyphosis; SVA, sagittal vertical axis; ODI, Oswestry Disability Index; SRS-22, Scoliosis Research Society-22 questionnaire.
Receiver operating characteristic curve analysis showing the cutoff value for the final Scoliosis Research Society-22 self-image score to predict high satisfaction. (area under the curve = .828, sensitivity = .819, and specificity = .732, P < .001).
Bar plot showing a comparison of the final sagittal parameters according to the self-image groups (score < 3.0 vs score ≥ 3.0). The final TK and SVA were significantly lower in the score ≥ 3.0 group than in the score < 3.0 group (29.6° vs 34.5°, P = .001 for the final TK; 27.4 mm vs 41.6 mm, P < .001 for the final SVA).
Discussion
The healthcare paradigm has shifted toward emphasizing individualized patient cases, with growing attention to patient satisfaction metrics in medical research.9,11,15 Understanding the key determinants of patient satisfaction is particularly crucial in ASD cases, given the complex spectrum of clinical manifestations and the highly invasive nature of surgical treatment. Although several studies have reported the factors affecting patient satisfaction after ASD surgery, few have comprehensively addressed the potential factors across patient factors, surgical variables, radiographic results, mechanical complications, and patient-reported outcomes. The present study identified the final SRS-22 self-image score as the most influential factor determining long-term satisfaction following extensive corrective surgery in patients with ASD. This finding underscores the importance of patient’s self-image perception in determining the success of surgery, beyond traditional radiographic parameters, and the occurrence of mechanical complications.
Mechanical Complications and Patient Satisfaction
Among various factors that potentially influence patient satisfaction after surgery, the occurrence of complications, particularly mechanical complications, is a primary concern among patients and surgeons.16,18,19 The effect of complications on patient satisfaction has been inconsistent in the literature. Yage et al have reported that the presence of severe adverse events, particularly mechanical complications necessitating reoperation, was a significant risk factor for lower pain and function scores in the SRS-22. 10 Bess et al identified that among the possible complications, the need for reoperation at any postoperative period, implant failure, proximal junctional failure significantly impacted patient’s willingness to undergo the same procedure again. 20 However, contrary to previous studies, Hamilton et al did not identify significant differences in satisfaction scores according to the development of major or minor complications, although they did not specify the detailed profiles of complications. 15 These conflicting results regarding the relationship between complication and patient satisfaction may result from the lack of control for potential confounders. In the present study, revision surgery for PJK or RF adversely affected patient satisfaction in the bivariate comparison (Table 4). The revision rates were significantly higher in the LS group than in the HS group studies (19.7% vs 11.1%, P = .022), based on bivariate analysis in agreement with findings of like Yagi’s and Bess’s studies. However, it did not emerge as an independent predictor of satisfaction in the multivariate analysis after adjusting for confounding factors, as in Hamilton’s study (Table 5). Therefore, even when revision surgery is necessary, optimizing patient perception of self-image through adequate attainment of sagittal alignment may mitigate dissatisfaction.
Radiographic Results and Patient Satisfaction
Previous studies have highlighted the importance of appropriately restoring and maintaining global sagittal alignment to enhance patient satisfaction. Alshabab et al examined 509 patients who underwent ASD surgery, and 38.7% of the patients reported low satisfaction (defined as SRS-22 satisfaction scores < 4.0). 11 Compared to the high-satisfaction group, the low- satisfaction group exhibited greater residual sagittal deformities at the 2-year follow-up, thereby suggesting that achieving optimal global alignment was a key determinant of high satisfaction. Similarly, Yagi et al have reported that 21.0% of patients had low satisfaction (defined as an SRS-22 satisfaction score < 3.0), and identified global alignment proportion (GAP) score as an independent predictor of low satisfaction. Specifically, patients with severely disproportionate GAP scores at 2 years were 4.6 times more likely to experience low satisfaction than those with proportionate alignment. 10 In a study by Hayashi et al, greater SVA (> 5 cm) has been identified as a significant risk factor responsible for low satisfaction at 2 years. 9 In agreement with previous studies, we also observed that the final TK and SVA was significantly greater in the LS group than in the HS group, suggesting that the LS group had worse final sagittal alignment than the HS group. To achieve a desirable SVA value at the final follow-up, ensuring appropriate SVA correction immediately after surgery through adequate PI-LL correction is crucial because poorly corrected global alignment (eg, SVA) after the index surgery would not improve, or even deteriorate, over time. Park et al have evaluated the final SRS-22 scores for patients categorized into appropriate correction and inappropriate correction based on 6-week PI-LL, PT, and SVA. 21 The appropriate correction group had significantly higher SRS-22 scores at 2 years and long-term follow-up (mean, 90.3 months) than the inappropriate correction group, underscoring the importance of immediate postoperative sagittal correction. In the present study, we observed no significant differences in the 6-week SVA values between the two groups (22.0 mm and 18.8 mm for the LS and HS groups, respectively) (Table 3). However, our results do not imply that immediate postoperative correction of SVA is independent of final satisfaction considering that the SVA values in both groups were within the optimal range. Possible explanation for these results is that the initially corrected SVA may have deteriorated alongside the TK during the follow-up period, as shown in the overall radiographic results (Figure 1). That is, as the follow-up periods extends, some degree of correction loss (eg, increase in TK and SVA) may occur either within the instrumentation or in the unfused segments. 12 Additionally, the occurrence of PJK can further deteriorate the global sagittal alignment. Therefore, to maintain an appropriate sagittal alignment at the final follow-up, a thorough understanding of related factors for correction loss and PJK is necessary to maintain sagittal alignment within optimal ranges at the final follow-up.22,23
Self-Image and Patient Satisfaction
The SRS-22 self-image score at the final follow-up was the most influential factor of patient satisfaction. This finding is consistent with a previous report demonstrating that self-image is a major factor affecting patient satisfaction.7,9 The self-image domain comprised five questions as follows: expected lifelong satisfaction with back shape (#4), perceived body image in clothing (#6), perception of trunk appearance (#10), impact of back condition on personal relationships (#14), and perceived attractiveness of current back condition (#19). Likewise, the questionnaires of the self-image domain largely reflect the status of global sagittal alignment. Although final TK and SVA were not significant in the multivariate analysis, both parameters were significantly greater in the LS group than in the HS group in the univariate analysis. This finding suggests that final sagittal alignment, represented by TK and SVA, has an impact on patient satisfaction. In a subgroup analysis, we also found that the final TK and SVA was significantly higher in the self-image score < 3.0 group than in the self-image score ≥ 3.0 group (34.5° vs 29.6°, P = .001 for TK; 41.6 mm vs 27.4 mm, P < .001 for SVA), indicating that TK and SVA significantly influenced patient’s perception of self-image (Figure 4). However, the final TK and SVA were not significant in the multivariate analysis. As TK and SVA is measured in 1-degree and 1-mm increments, statistically significant differences in these parameters may not necessarily translate into a clinically meaningful impact on patient satisfaction. Nevertheless, considering that final suboptimal sagittal alignment status (eg, increased TK or SVA) is related with poor self-image perception, efforts should be made to restore and maintain the sagittal alignment properly.
Limitations
We have to acknowledge some limitations. First, the single-center study is an inherent limitation. Nevertheless, this issue could be considered a strength of the current study because the surgical indications, surgical methods, and postoperative management protocols have remained relatively consistent. Moreover, female predominance of study population may introduce a potential gender bias not fully representing the whole deformity population. Second, we utilized the mean score from the SRS-22 satisfaction subdomain to categorize patients, as employed in previous studies9,11,15; however, such methods based on a numerical scale may have limitations in accurately assessing the true patient satisfaction. Additionally, since the SRS-22 scoring system was originally developed and optimized for idiopathic scoliosis, it may not be fully appropriate for evaluating degenerative-type ASD patients, potentially introducing limitations. Third, as patient satisfaction is a subjective perception, it may be influenced by various subjective factors, such as patient experience during hospitalization or the rapport between the patient and the physician. Finally, the study cohort comprised all Asian patients. However, perceptions of satisfaction levels can differ according to ethnicity. Yagi et al. compared patient satisfaction levels between Japanese and American patients. 24 They have reported that surgical treatment was similarly effective in both groups in terms of ODI and SRS-22 scores. However, satisfaction scores were significantly lower in the Japanese patient group than in the American patient group, despite similar SRS-22 pain and function scores. Therefore, differences in lifestyle and cultural expectations may affect patient satisfaction in ASD surgery.
Conclusions
Among various surgical objectives, such as restoring sagittal alignment, minimizing mechanical complications, enhancing functional status, reducing pain, improving self-image, and decreasing psychological stress, achieving satisfactory self-image perception at the last follow-up was the most influential factor for high satisfaction after ASD surgery. Considering self-image perception was associated with sagittal alignment status, efforts should be directed toward achieving and maintaining global sagittal balance within an optimal range.
Footnotes
Declaration of Conflicting Interests
The author(s) declared no potential conflicts of interest with respect to the research, authorship, and/or publication of this article.
Funding
The author(s) received no financial support for the research, authorship, and/or publication of this article.
Ethical Statement
Data Availability Statement
The datasets generated during and/or analyzed during the current study are not publicly available due to the inclusion of personal information, but are available from the corresponding author on reasonable request.