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Health Services Research

A Multicenter Study of the Outcomes of the Surgical Treatment Of Adolescent Idiopathic Scoliosis Using the Scoliosis Research Society (SRS) Outcome Instrument

Merola, Andrew A., MD*†; Haher, Thomas R., MD; Brkaric, Mario, MD*; Panagopoulos, Georgia, PhD; Mathur, Samir, MD*; Kohani, Omid, MS III*; Lowe, Thomas G., MD§; Lenke, Larry G., MD; Wenger, Dennis R., MD; Newton, Peter O., MD#; Clements, David H. III,, MD**; Betz, Randal R., MD††

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Until recently, there has been no standardized questionnaire available to evaluate patient based outcomes for the operative treatment of adolescent idiopathic scoliosis (AIS). Surgical outcomes have traditionally been based on process measures, such as the degree of curve correction. 4,17 Relatively few studies have addressed patient-oriented measures of success. 1,2,7,19 Furthermore, the studies that did address this issue did not use a standardized, patient-specific outcome questionnaire. 5,11,12 It was apparent that the need existed for an outcome questionnaire by which patient satisfaction could be assessed.

To assess the impact of the surgical treatment of AIS, the Scoliosis Research Society (SRS) charged an outcomes committee with the development of a patient-oriented outcome questionnaire. 6,10 The goal of the SRS 24 questionnaire is to provide a high-quality, standardized, validated, and broadly accepted questionnaire that can be adopted for use across many clinical investigations and will consistently yield outcome information for future data analysis. A search of the English language literature indicates that there exists no prospective study using the SRS 24 instrument reporting on the outcome of AIS that has been surgically treated. The goal of the present study is to prospectively evaluate the impact of the surgical treatment of AIS as perceived by the patient.

Materials and Methods

The SRS 24 questionnaire was used as our outcome measurement tool. The SRS 24 questionnaire is a disease-specific, reliable, and validated questionnaire used to assess outcomes in AIS. 10 The questionnaire consists of 24 questions designed to assess several aspects of outcome as perceived by the patient. Each question contains an odd number of responses, comprising a Likert-type scale, except for three yes-or-no type questions, which represent an all-or-none response. The 24 questions represent seven major patient-based outcome domains: Pain, General Self-Image, Postoperative Self-Image, Postoperative Function, Function From Back Condition, General Level of Activity, and Satisfaction. All questions are rated 1 to 5, with 5 being the optimal response (see Appendix). For the purposes of our statistical analysis, each domain was analyzed using a mean score (Table 1).

Table 1
Table 1:
SRS 24 Questions That Correspond to Each Domain

Seven scoliosis centers within the United States participated in this study. These centers were located in New York City, Philadelphia, St. Louis, Denver, and San Diego. A total of 343 patients evaluated at these centers and diagnosed with AIS were administered the questionnaire during their initial patient contact and at 24 months after surgery. Inclusion criteria for this study were as follows: AIS, age range 13–18 years, surgical treatment (anterior or posterior), minimum 2-year follow-up, completed questionnaires (no blank responses), and preoperative and 24-month postoperative data. A total of 89 patients had some blank or illegible responses, and 12 were lost to follow-up. Using these inclusion criteria, a total of 242 patients are included in the current study population. The mean age was 14 ± 2.3 years (range 13–18 years). There were 202 female and 40 male participants; 111 had anterior and 131 had posterior surgery. Mean curve size was 54.3 ± 8.2°. Curve magnitude was divided into two groups: <54° (n = 130) and >55° (n = 112). The range of curve sizes was 40–80°. Anterior surgery was indicated for single major curves. Posterior surgery was indicated when a secondary structural curve was present.

Each patient was assigned an identification number to maintain confidentiality. The preoperative and postoperative data points were paired according to domain. The paired group of 242 patients was analyzed with Statistical Package for Social Science (SPSS; Chicago, IL). For the total cohort, paired-samples t tests were used on the four domains measured both before and after surgery. These domains are Pain, General Self-Image, Function From Back Condition, and General Level of Activity. The remaining three postoperative domains (Postoperative Self-Image, Postoperative Function, and Satisfaction) were analyzed descriptively. Data are presented as mean ± standard error of the mean. A P value of <0.05 was considered statistically significant.

Group comparisons were made as determined by type of surgery, gender, and curve magnitude. Independent-samples t tests were used for all postoperative-only domains. If independent-samples t tests alone were separately performed to detect differences between groups in each of the four domains measured both before and after surgery, this would not accurately reflect the change of scores as patients move from preoperation to postoperation. To control for possible preoperative differences on these four domains, difference scores were used. Difference scores were calculated by subtracting the preoperative score from the postoperative score for each of the four domains. Independent-samples t tests were subsequently used on the difference scores. Question 18 is a postoperative-only question, and all other pain questions are asked both before surgery and after surgery. Difference scores cannot be calculated for this question because it has no preoperative analog. Therefore, this question was not included in the data analysis. Regression analysis was performed to examine whether there was a linear association between magnitude of curve correction and outcome.


Total Cohort

Pain, General Self-Image, Function From Back Condition, and Level of Activity all demonstrated statistically significant improvement as compared with preoperative status (P < 0.001) (Figure 1). Preoperative Pain scores demonstrated a mean of 3.68 ± 0.05. Postoperative Pain scores demonstrated a mean of 4.63 ± 0.03. The range of Pain scores was 1.17–5.0 before surgery and 2.0–5.0 after surgery. Scores of <4 were present in 56% of preoperative patients. Postoperative Pain scores <4 were present in only 6% of patients. Postoperative scores for Self-Image and Function were 3.82 ± 0.04 and 3.11 ± 0.07, respectively. A total of 94% of patients were satisfied with the results of surgery; scores were 4.67 ± 0.03. The range of Satisfaction scores was 2.33–5.0.

Figure 1
Figure 1:
The total cohort of patients with a comparison of Preoperative and Postoperative Pain, General Self-Image, Function From Back Condition, Activity Level, Postoperative Self-Image, Postoperative Function, and Satisfaction.

Curve Magnitude

Independent-samples t tests performed between the two curve groups on the difference scores did not demonstrate any significant differences (P > 0.10). Curves <55° had a mean correction of 27.6, whereas curves >55° yielded a mean correction of 38.7 (60% and 60.5% correction, respectively). Patients with curves from 40° to 54° demonstrated similar Pain scores as patients with curves ≥55°. No statistically significant differences were seen in postoperative Self-Image or Postoperative Function. The only statistically significant difference observed was on Patient Satisfaction scores. Patients reported greater Satisfaction in the ≤54° curve group. Satisfaction was 4.77 ± 0.05 versus 4.55 ± 0.10 (P = 0. 05) (Table 2).

Table 2
Table 2:
Curve Magnitude

Magnitude of Curve Correction

A mean and median of 31° was calculated for magnitude of curve correction for the total cohort. Regression analysis, correlation tables, and scatter plots showed no significant correlation between magnitude of curve correction and all outcome domains (Table 3).

Table 3
Table 3:
Correlations Table: Magnitude of Surgical Correction


Comparisons between male and female patients on difference scores of the four domains did not yield any significant differences. There was no statistical difference in Postoperative Self-Image, Postoperative Function, or Satisfaction from the surgery between male and female respondents in this study (P > 0.10) (Table 4).

Table 4
Table 4:

Surgical Procedure

Analysis of the difference scores did not demonstrate any significant differences in all four domains (P > 0.10). After surgery, no significant differences were obtained in Function, Satisfaction, or Self-Image (Table 5).

Table 5
Table 5:
Surgical Procedure


The goal of the study is to assess the patient’s perception of the surgical treatment of AIS, using the SRS 24 questionnaire.

Back pain was present in our preoperative patients with AIS; a mean score of 3.68 was identified. After surgery, this improved to a mean of 4.63; this represents an improvement of 0.95 points. The mean preoperative Pain score represents a series of adolescent patients between the ages of 13–18 years with curves between 40° and 80° who experience back pain before surgery. The prevalence of back pain in a pediatric population in general is variable and is noted to be between 7% and 40%. 3,8,9,14,15,18

Studies regarding pain in the scoliotic population, such as the St. Justine Cohort study, report pain and its association with surgery in a retrospective manner. 13,16 Our study reports the results on pain levels in a prospective fashion as compared with the patients’ preoperative status. A baseline preoperative relatively “painful” condition exists within our cohort. The score for preoperative pain averages 3.68 ± 0.05. The two-year follow-up averages 4.63 ± 0.03, which represents an overall improvement of one clinical grade per question answered. The three-response represents a moderate pain perception characterized by patients who take pain medications and experience back pain more often than not. The four-response indicates patients that rarely experience back pain as well as require either no pain medication or nonsteroidals only.

This study has demonstrated that pain scores improve as a result of surgery. The ability of the instrument to demonstrate the existence of preoperative pain in this series represents the first prospective quantitative evidence of pain using the SRS 24. The range indicates a significant amount of pain for some patients with pain scores as low as 1. No postoperative scores for pain were in the one response area. This response indicates a positive postoperative pain trend, as does the overall mean response.

In addition to reduction in preoperative pain, statistically significant improvements were seen in the General Self-Image, Function From Back Condition, and Level of Activity domains. This demonstrates that the surgical treatment in our series of patients has resulted in a perceived benefit in the aforementioned domains. The perceived beneficial effect of surgery encompasses self-image as well as functional domains, indicating a benefit beyond pain perception.

When both the <55° curve group and the >55° curve group are assessed for postoperative correction, we find that the absolute percentage is equal for both (60%). Smaller curves acquire a smaller magnitude of postoper- ative correction than do larger curves. The larger magnitude curves are proportionately “more” corrected than the smaller curves, but this does not alter any of the outcome parameters other than Satisfaction. Satisfaction for Group 1 was 4.77 ± 0.05 versus 4.55 ± 0.10 for Group 2. Ranges were 2.33–5. The Satisfaction data, although statistically different between the two groups, were still in the realm of a positive response, >4.5 for both groups. Both groups would agree to undergo surgery again. A response of 4 indicates a high degree of patient satisfaction. Both groups scored 4 or better, and it is virtually impossible to distinguish these responses on a clinical basis. Satisfaction data are unique in so much as they indicate a patient’s perception of their “comfort” with the procedure as well as all aspects of the surgical process.

Analysis showed no significant correlation between magnitude of curve correction and outcome scores. Magnitude alone is not in and of itself the only way to measure the success of surgery. The ability to balance the curve, restore a waistline, eliminate the rib hump, prevent a deterioration in future pulmonary function, and improve overall self-image may be far more important to outcome than absolute magnitude alone. Corrections need to be weighed against curve balance and all of the other factors that are more determinant of the art of scoliosis surgery rather than the desire to achieve maximum magnitude correction.


Preoperative pain exists in our adolescent scoliosis population, with a mean of 3.68. Pain is improved to 4.63 at the 2-year postsurgical follow-up. The present study demonstrates the ability of surgery to improve the outcome of patients afflicted with AIS. Statistically significant improvements were likewise seen in the General Self-Image, Function From Back Condition, and Level of Activity domains.

Key Points

  • Preoperative pain scores were 3.68 of 5 in our population.
  • Postoperative pain scores improved to 4.63.
  • Pain, General Self-Image, Function From Back Condition, and Level of Activity all demonstrated statistically significant improvement as compared with preoperative status.
  • The present study demonstrates the ability of surgery to improve the outcome of patients with adolescent idiopathic scoliosis.
  • This is a multicenter study of the outcomes of the surgical management of adolescent idiopathic scoliosis in 242 patients.


Scoliosis patient questionnaire with answer key.




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