Next, a comparison was performed between surgically treated patients with preoperative large deformities (>40°) and nontreated patients with small deformities (20°–40°) to identify the isolated effect of deformity magnitude (preoperative vs. nonoperative groups). The SRS questionnaire was able to discriminate between the 2 groups based on curve magnitude. Patients with small deformities reported significantly (P < 0.001) higher scores in all domains as well as the Total score compared to those with large deformities. This difference in scores (better quality of life with less deformity) was most notable for the Pain domain (preoperative: 3.7 ± 0.7 vs. nonoperative: 4.3 ± 0.6) and the Self-Image domain (preoperative: 3.6 ± 0.9 vs. nonoperative: 4.2 ± 0.8). The isolated effect of deformity magnitude based on the Total score was found to be positive (0.5) (Table 3).
The final analysis investigated the combined effect of surgery (spinal fusion and deformity reduction) on quality of life (preoperative vs. postoperative groups). AIS patients' quality of life significantly improved (P < 0.001) after surgical correction in the domains of Pain, Self-Image, and General Function. Again, the most significant improvements occurred in the Pain domain (preoperative: 3.7 ± 0.7 vs. postoperative: 4.3 ± 0.6) and the Self-Image domain (preoperative: 3.6 ± 0.9 vs. postoperative: 4.4 ± 0.6). The Total score also improved significantly (P < 0.001) and a trend towards improvement was noted in the Activity domain (P = 0.07). The combined effect of surgery based on the Total score was found to be positive (0.3) (Table 4).
Table 5 summarizes our findings for the isolated effect of spinal fusion, the isolated effect of deformity magnitude and the combined effect of surgery for each of the 4 preoperative domains and the Total score. A consistent additive relationship is observed for each of the 5 scores. For example, the significant improvement in the Pain domain due to surgery appears to be due to deformity correction and is not effected by spinal fusion. Similarly, improvement in the Function domain scores is only due to deformity correction. The Activity domain, on the other hand, is affected by both spinal fusion and deformity magnitude. Spinal fusion negatively impacts Activity (−0.3) while deformity correction has a positive effect (+0.4). Along the same lines, the overall positive effect of surgical correction (Total score change of +0.3) is due to the sum of both the isolated effects of spinal fusion (−0.2) and deformity reduction (+0.5).
In the 1960s, the advent of Harrington distraction rods dramatically changed the concept of surgical correction of scoliosis.17 Although corrective spine surgery has evolved since the Harrington rod era, spinal arthrodesis with instrumentation is still the most common surgical treatment option for progressive scoliosis. The fundamental concern of the scoliosis surgeon when recommending a surgical fusion is to preserve the quality of life of the patient by preventing long-term detrimental effects of progressive scoliosis, thereby averting worsening cosmesis, impaired pulmonary function, severe back pain, disablement, and further treatment in adulthood.18,19 During adolescence, however, AIS patients tend to largely focus on their altered physical appearance, mainly due to an increased awareness of body image during adolescent development, with an ultimate desire to improve their self-image and psychological well being.2,20,21 Historical studies that used simple questionnaires have reported a reduction of quality of life in adolescents with scoliosis; specifically related to depression, back pain, limited physical ability, and a negative self perception.22–24 Although the specific indications of corrective spine surgery may differ slightly between surgeon and patient, an overall improvement in quality of life of the affected patient is the comprehensive goal.
In order to determine if corrective surgery does in fact enhance scoliosis patients' quality of life, Haher et al designed the SRS Outcomes Instrument (SRS-24). The SRS-24 is a disease-specific questionnaire that has been widely used as a validated instrument to evaluate the quality of life and efficacy of treatment in patients with AIS.4 Several studies have demonstrated that deformity correction, specifically postoperative thoracic curve magnitude, has a significant inverse correlation with SRS questionnaire scores (the smaller the deformity, the higher the SRS score and quality of life) although curve type, degree of curve correction, and surgical approach did not correlate with patients' perceived surgical outcome.1,12–16 While reducing a patient's deformity may improve their overall quality of life, the experience of surgery has been reported by patients to be “hard” possibly due to postoperative pain,25 activity restrictions, decreased postoperative trunk flexibility, and visible scarring.
Quality of life after scoliosis surgery has been evaluated using a variety of validated patient questionnaires. Cochran et al reported that surgically treated patients revealed no lessened activity or back pain, and functioned at the same level when compared to controls without scoliosis.26 In support of these findings, Danielsson et al described surgically treated patients to have approximately the same quality of life as the general population; although, a small group of patients experienced severe psychosocial difficulties and a few were physically disabled due to their spinal fusion.27 Conversely, Andersen et al reported that surgically fused patients experienced more pain, felt less healthy, and had reduced activities of daily living when compared to normal adolescents.28 On the basis of these conflicting reports, further dissection into the components was performed to determine specifically how the surgical correction of scoliosis affects the quality of life of patients.
Despite earlier studies, the difficulties of surgery that patients experience and its effect on their quality of life have not been widely investigated. In order to determine how a spinal fusion component itself impacts a patient's quality of life, the effect of the surgical procedure has been isolated from the effect of the reduced deformity in this analysis. Thus, a quality of life comparison between surgical and nonsurgical AIS patients was performed while controlling for the magnitude of spinal deformity. In this study, patients who had 20°–40° of untreated scoliosis were compared to patients who had 20°–40° of scoliosis 2 years after surgical correction. While this comparison does not necessarily take into account the residual effects of having had a prior large deformity (e.g., changes in the chest wall and pulmonary function) it is the best possible method to evaluate the isolated effect of surgery while controlling for deformity magnitude. The surgically fused patients with 20°–40° of scoliosis did not report increased pain, lower self image, or reduced general function when compared to the untreated patients with similar degrees of deformity; however, a surgical fusion did result in a statistically significant reduction in the Activity domain score as well as in the Total SRS score. The absolute reduction in the Activity domain score and Total score in the surgically fused patients was small (0.2–0.3). It should be noted that routine postoperative activity restriction imposed by the treating surgeons were removed by at least 1-year postoperative.
Although statistically significant differences were found between treated and untreated patients' quality of life, these statistical findings may have little clinical significance to the patient/surgeon. In attempt to elucidate statistical significance versus clinical significance in quality of life instrument scores, Jaeschke et al defined the Minimal Clinically Important Difference (MCID) as the smallest difference in a score that patients perceive as beneficial.29 Berven et al studied the concept of MCID and its usefulness in the SRS Outcomes Instrument and reported the MCID ranged from 0.1 to 0.85, yet the range was different for each domain.30 In this study, the absolute reductions in the Activity domain and Total score for surgically fused patients were within this range, suggesting that the isolated effect of a surgery on quality of life may be perceived as clinically relevant by patients. These results contradict Helenius et al earlier report that decreased spinal mobility did not correlate with patients' SRS scores.31 However, Asher et al noted that although Function and Activity scores were significantly decreased 3 months after surgery, they returned to baseline at the 6 month time point.32 Psychological factors such as anxiety for possible breakage of instrumentation might affect patients' activity; however, such psychological factors are likely to decrease over time if the patient does not experience pain or postoperative complications.
SRS scores were also compared between patients with large (preoperative) curves and patients with small (untreated) curves in order to reconfirm that deformity magnitude alone has a measurable impact on quality of life. Furthermore, preoperative and postoperative SRS scores in surgically treated patients were analyzed to gauge the overall effect of surgical correction (combined effects of surgery and deformity reduction) on AIS patients' quality of life. Both the isolated effect of deformity reduction and overall effect of surgical correction were positive in the all domains and the Total score, confirming previous reports.12–16 Although the differences were small (0.1- 0.6, on a 1–5 scale), they were also within the range of MCID, suggesting possible clinical relevance.
The overall positive effect of surgical correction on AIS patients' quality of life depended on the individual effects of spinal fusion and deformity reduction. Although the isolated effect of spinal fusion reduced patients' activity and therefore negatively affected quality of life, a smaller curve magnitude and improved cosmesis after surgery positively affected all domains and ultimately resulted in a better quality of life for AIS patients after surgical treatment. The positive effect on quality of life from surgical correction is dominated by the effect of deformity magnitude reduction with minimal downside effects (from the 2-year postoperative quality of life standpoint) of spinal fusion.
- The isolated effect of spinal fusion had a modest negative impact on quality of life (−0.2) in patients with AIS.
- The negative effect of spinal fusion was attributed to the Activity domain.
- A decreased deformity had a significant positive effect on AIS patients' quality of life (+0.5).
- The overall positive effect of surgical scoliosis correction on quality of life (+0.3) was accounted for by the negative effect of spinal fusion (−0.2) and the positive effect of deformity magnitude reduction (+0.5).
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Keywords:© 2009 Lippincott Williams & Wilkins, Inc.
adolescent idiopathic scoliosis; quality of life; effect of spinal fusion; effect of deformity correction