Dissecting the Effects of Spinal Fusion and Deformity Magnitude on Quality of Life in Patients With Adolescent Idiopathic Scoliosis
Tsutsui, Shunji MD*; Pawelek, Jeff BS*; Bastrom, Tracey MA*; Lenke, Lawrence MD†; Lowe, Thomas MD‡; Betz, Randal MD§; Clements, David MD§; Newton, Peter O. MD*
From the *Department of Orthopedic Surgery, Rady Children's Hospital, San Diego, CA; †Department of Orthopedic Surgery, WA University, St Louis, MO; ‡Deceased (Department of Orthopedic Surgery, Woodridge Spine, Wheat Ridge, CO); and §Department of Orthopedic Surgery, Shriner's Children's Hospital, Philadelphia, PA.
Acknowledgment date: February 21, 2008. First revision date: April 29, 2008. Second Revision date: May 30, 2008. Acceptance date: June 6, 2008.
The device(s)/drug(s) is/are FDA-approved or approved by corresponding national agency for this indication.
Corporate/Industry funds were received in support of this work. Although one or more of the author(s) has/have received or will receive benefits for personal or professional use from a commercial party related directly or indirectly to the subject of this manuscript, benefits will be directed solely to a research fund, foundation, educational institution, or other nonprofit organization which will receive benefits for personal or professional use from a commercial party related consultancies, royalties, stocks, stock options, decision making position.
Supported by the Harms Study Group from DePuy Spine Inc and by the Rady Children's Specialists Foundation Orthopedic Research and Education Fund.
Study was conducted at Rady Children's Hospital and Health Center San Diego, CA, with the membership of the Harms Study Group.
Address correspondence and reprint requests to Peter O. Newton, MD, 3030 Children's Way, Suite 410, San Diego, CA 92123; E-mail: email@example.com.
Study Design. A retrospective review of scores from the Scoliosis Research Society outcomes instrument (SRS-24 questionnaire).
Objective. To quantify the isolated effects of spinal fusion and deformity magnitude on quality of life in patients with adolescent idiopathic scoliosis (AIS).
Summary of Background Data. Significant improvements in 2-year postoperative SRS-24 questionnaire scores have been reported despite the loss of spinal motion due to instrumentation and arthrodesis. As deformity reduction may influence patient perception, it has been difficult to isolate the effect of spinal fusion on quality of life after scoliosis surgery.
Methods. SRS-24 scores were compared between 3 cohorts of AIS patients (preoperative, postoperative, and nonoperative) using an ANOVA (P < 0.05) to determine the isolated effects of spinal fusion and deformity magnitude. Preoperative SRS-24 scores were collected from a group of patients with preoperative major Cobb angles greater than 40° (n = 194). Postoperative SRS-24 scores were collected from patients with preoperative major Cobb angles greater than 40° and 2-year postoperative major Cobb angles between 20° and 40° (n = 196). Finally, SRS-24 scores were collected from a nonoperative group of patients with major Cobb angles between 20° and 40° (n = 112).
Results. Spinal fusion was found to have a negative isolated effect on the Activity domain (−0.3) and on the Total score (−0.2) (P = 0.001) of the SRS-24 questionnaire (score range: 1–5). A smaller deformity magnitude, on the other hand, was found to have a significantly positive isolated effect on all 4 preoperative domains (P < 0.001) and on the Total score (P < 0.001). The combined effect of surgery (spinal fusion and deformity correction) was found to be significantly positive for the Total score (P < 0.001) and for the domains of Pain, Self-Image, and Function (P < 0.001).
Conclusion. Spinal fusion has an isolated negative effect on AIS patients' quality of life (Total score) mostly due to a decrease in scores of the Activity domain. The overall positive effect of surgery depends on the individual effects of spinal fusion (slight reduction in quality of life) and deformity reduction (modest improvement in quality of life).
Adolescent idiopathic scoliosis (AIS) is a spinal deformity that occurs in otherwise healthy adolescents and teenagers. AIS patients often have an obvious trunk imbalance and/or rib prominence depending on the magnitude and location of the spinal deformity. Concern about curve progression and its impact on trunk shape and patient perceived quality of life, combined with pubertal development and its effect on psychosocial perception and behavior, may lead AIS patients to have increased anxiety about their physical appearance.1–3 The quality of life in AIS patients has been widely studied via self-reported methods, as this data has been found to yield useful information that is reflective of patients' perception of the condition and the overall efficacy of current treatments. The Scoliosis Research Society outcomes instrument (SRS-24 questionnaire) was designed as a disease-specific questionnaire, which has been widely used as a valid instrument to evaluate the quality of life and efficacy of treatments in patients with AIS.4–11
In the modern treatment of progressive AIS, spinal fusion with instrumentation is the definitive treatment to prevent curve progression and improve trunk deformity. Merola et al reported that surgical correction of scoliosis improved patient outcomes using the SRS-24 instrument at 2-year follow-up.12 However, surgical intervention may negatively impact the patient's function and quality of life due to a large visible postoperative scar, decreased spinal flexibility, and potential discomfort. The change in quality of life for surgically treated patients with scoliosis likely is affected by both the reduction in deformity as well as the loss of motion associated with such surgery.
Regarding the isolated effect of deformity magnitude on quality of life, several authors have reported that the Cobb angle measurement has a negative correlation with SRS scores and the SRS questionnaire was able to discriminate varying magnitudes of deformity.13–16 To our knowledge, no study has demonstrated the independent effect of spinal fusion on AIS patients' quality of life. The purpose of this study was to quantify the isolated effect of spinal fusion, independent of the degree of spinal deformity, by comparing postoperative SRS scores of surgically fused patients with those of nontreated patients with similar degrees of scoliosis for both groups. In addition, the isolated effect of deformity magnitude on quality of life was evaluated by comparing the preoperative SRS scores of surgically treated patients with those of nontreated patients whose deformity was below surgical indications. Furthermore, the overall effect of surgical correction (combined effect of surgical fusion and deformity reduction) was also confirmed by comparing preoperative SRS scores with postoperative scores in 2 cohorts of patients (Figure 1).
Materials and Methods
After institutional review board approval a retrospective chart and radiographic review of patients with adolescent idiopathic scoliosis was performed. Nonsurgical patients evaluated at our institution, with a major Cobb deformity between 20° and 40°, were included in the nonoperative group. A total of 112 nontreated patients who fit the inclusion criteria and who had completed an SRS-24 questionnaire at their initial visit between 2004 and 2006 were identified. The nonoperative group included 19 males and 93 females with an average age of 16 ± 2 years (range: 9–23years). The main thoracic deformity averaged 27.8° ± 6.7°, while the thoracolumbar/lumbar deformity averaged 30.3° ± 5.8°. None of these patients had undergone earlier spine surgeries or been prescribed a brace.
A multicenter AIS database was used to identify surgically treated patients who had preoperative major curves measuring more than 40° with residual major curves between 20°and 40°. Preoperative SRS-24 scores were recorded from a group of patients with less than 2-year follow-up (preoperative group), while a third group of patients with 2-year postoperative SRS-24 scores were also recorded (postoperative group). The preoperative group (n = 194) included 28 males and 166 females with an average age of 15 ± 2 years (range: 11–21years). The main thoracic deformity in this group averaged 54.3° ± 17.4° and the thoracolumbar/lumbar deformity averaged 43.0° ± 16.6°. Finally, the postoperative group (n = 196) included 32 males and 164 females. The average age at the 2-year follow-up visit was 17 ± 2 years (range: 12–24years). The 2-year main thoracic deformity averaged 26.2° ± 6.5° and the thoracolumbar/lumbar deformity averaged 19.2° ± 7.8°. All surgical patients were treated between 1995 and 2007.
The SRS-24 questionnaire consists of 7 major patient-based outcome domains: Pain, General Self-Image, General Function, Overall Level of Activity, Postoperative Self-Image, Postoperative Function, and Satisfaction. As not all patients had a surgical procedure, only the domains of Pain, General Self-Image, General Function, and Overall Level of Activity were analyzed. A total score was calculated using the 4 individual domains. All questions in each domain were given a score from 1 to 5, with 5 being the optimal response. The SRS scores were normalized by dividing the domain scores by the number of questions answered in order to account for the variation in the number of questions answered in each domain.
Statistical Package for Social Science (SPSS, Chicago, IL) was used to perform analysis of variance (ANOVA) to compare the 3 groups of patients. To determine the isolated effect of spinal fusion, 2-year postoperative SRS-24 scores of surgically fused patients with “small” deformities (20°–40°) were compared with those of the nontreated patients with similar deformities (postoperative vs. nonoperative groups). The isolated effect of deformity magnitude was determined by comparing SRS-24 scores from patients with “large” preoperative deformities (>40°) with those of nontreated patients with “small” deformities (20°–40°) using an ANOVA (preoperative vs. nonoperative group). Finally, preoperative SRS scores of the surgically treated patients were compared with 2-year postoperative scores using ANOVA to evaluate the combined effect of surgery; spinal fusion and deformity reduction (preoperative vs. postoperative groups). A P < 0.05 was set to determine statistical significance for all analyses.
Demographic and radiographic data for the 3 groups of patients (nonoperative, preoperative and postoperative) are presented in Table 1. A comparison of SRS scores between nontreated patients with small deformities (20°–40°) and surgically fused patients with similar deformities (20°–40°) was performed in order to identify the isolated effect of spinal fusion (nonoperative vs. postoperative groups). Surgically fused patients reported statistically (P = 0.001) lower activity (4.5 ± 0.6) than the nontreated patients (4.8 ± 0.5). This also carried over to the Total score with significantly lower scores (P < 0.001) for the surgically fused patients (4.2 ± 0.4) than the nontreated patients (4.4 ± 0.4). The isolated effect of spinal fusion based on the Total score was negative (−0.2) (Table 2).
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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adolescent idiopathic scoliosis; quality of life; effect of spinal fusion; effect of deformity correction
© 2009 Lippincott Williams & Wilkins, Inc.
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