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Patient-Reported SRS-24 Outcomes Scores After Surgery for Adolescent Idiopathic Scoliosis Have Improved Since the New Millennium
Spine Deformity 7 (2019) 917e922 www.spine-deformity.org
Patient-Reported SRS-24 Outcomes Scores After Surgery for Adolescent Idiopathic Scoliosis Have Improved Since the New Millennium Tracey P. Bastrom, MAa, Carrie E. Bartley, MAa, Peter O. Newton, MDa,*, Harms Study Groupb a
b
Rady Children’s Hospital, 3020 Children’s Way, San Diego, CA, 92123, USA Setting Scoliosis Straight Foundation, 2535 Camino Del Rio S. Suite 325, San Diego, CA, 92108, USA Received 2 August 2018; revised 5 November 2018; accepted 8 January 2019
Abstract Study Design: Observational. Objective: To examine changes in patient-reported two-year postoperative outcomes via the Scoliosis Research Society (SRS)-24 Outcomes Instrument from 2001 through 2015. Summary of Background Data: Techniques for correction of adolescent idiopathic scoliosis (AIS) have evolved over the years, but it is unclear how these changes have impacted patient-reported outcomes. Methods: AIS patients with two-year postoperative follow-up from a prospective multicenter registry were divided into three-year groups based on trends in surgical approach and construct type (2010e2014: 52% anterior, 43% posterior hybrids; 2005e2011: 3% anterior, 5% posterior hybrids; 2012e2015: 0% anterior, 0.2% posterior hybrids). Because of the ordinal scale (1-5) and bipolar nature of the response sets for the SRS-24, domain/total scores were categorized as <3 (predominantly negative) or 4-5 (predominantly positive). Variables were compared across the three groups. Results: A total of 1,695 patients were analyzed; 172 (2010e2014), 926 (2005e2011), and 597 (2012e2015). Average age was 14.7 2 years, the average primary curve was 55 13 , and the group was primarily female (82%). There was a decline in the rate of positive scores for preoperative pain and self-image across the three groups (p ! .05). There was an increase in the rate of positive scores for twoyear postoperative self-image after surgery, function after surgery, and satisfaction (p ! .05). Decreases in length of hospital stay, blood loss, surgical time, preoperative kyphosis, and postoperative trunk shift were observed (p ! .05). Increases were observed in levels fused, preoperative major coronal curve, preoperative rib prominence, preoperative trunk shift, percentage correction of major curve, kyphosis restoration, and the rate of double/triple curves (p ! .05). Conclusion: The percentage of patients with positive postoperative SRS scores has increased in the modern era, providing evidence that newer surgical techniques are resulting in improved outcomes based on the patients’ perspectives. Interestingly, recent patients were more afflicted with negative pain and self-image before surgery. Ó 2019 Scoliosis Research Society. All rights reserved. Keywords: Patient reported outcomes; Adolescent idiopathic scoliosis; SRS-24; Scoliosis
Author disclosures: TPB (grants from Setting Scoliosis Straight Foundation, during the conduct of the study), CEB (grants from Setting Scoliosis Straight Foundation, during the conduct of the study), PON (grants from Setting Scoliosis Straight Foundation, during the conduct of the study; grants and other from Setting Scoliosis Straight Foundation and Scoliosis Research Society [SRS]; other from Rady Children’s Specialists; grants, personal fees, and nonfinancial support from DePuy Synthes Spine and K2M; grants from EOS Imaging and NuVasive; personal fees from Thieme Publishing and Cubist; other from Electrocore; other from International Pediatric Orthopedic Think Tank; grants, nonfinancial support, and other from Orthopediatrics; grants and nonfinancial support from Alphatech; grants from Mazor Robotics, outside the submitted work; in addition, PON has a patent ‘‘Anchoring Systems and Methods for Correcting Spinal Deformities’’ (8540754) with royalties paid to DePuy Synthes Spine; a patent ‘‘Low Profile Spinal Tethering Systems’’ (8123749) licensed to
DePuy Spine, Inc.; a patent ‘‘Screw Placement Guide’’ (7981117) licensed to DePuy Spine, Inc.; a patent ‘‘Compressor for Use in Minimally Invasive Surgery’’ (7189244) licensed to DePuy Spine, Inc.; and a patent ‘‘Posterior Spinal Fixation’’ pending to K2M), Harms Study Group (grants from DePuy Synthes Spine and EOS Imaging, during the conduct of the study; grants from NuVasive, K2M, Inc., Medtronic, and Zimmer Biomet, outside the submitted work). This study was conducted at Rady Children’s Hospital, San Diego, CA. IRB approval: IRB approval was obtained for this study (approval no. 150406, University of California, San Diego). *Corresponding author. Chief Division of Orthopedics, Department of Orthopedic Surgery, Rady Children’s Hospital, University of California, San Diego, 3030 Children’s Way, MC5062, San Diego, CA, 92123, USA. Tel.: (858) 966-6789; fax: (858) 966-7494. E-mail address: [email protected] (P.O. Newton).
2212-134X/$ - see front matter Ó 2019 Scoliosis Research Society. All rights reserved. https://doi.org/10.1016/j.jspd.2019.01.007
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Introduction Significant changes to the approach, constructs, and intraoperative techniques used for surgical correction of adolescent idiopathic scoliosis (AIS) have been made over the last few decades. Recent data suggest that during the last 20 years, anterior-only approaches for the treatment of AIS have dramatically decreased and allepedicle screw constructs have increased [1]. The shift to using posterior only approaches for all curve types because of their ability to achieve greater correction has been well documented, even for the treatment of larger curves [2-6]. This tendency toward posterior-only correction can largely be attributed to the efficacy of pedicle screw constructs [7-12]. Along with these changes, the ability to assess and measure the true scoliotic deformity in three dimensions (3D) has been enhanced with the introduction of technology that allows 3D reconstruction of the spine with low radiation exposure [13-16]. This greater understanding of the true 3D deformity and the use of other intraoperative methods to improve correction in all three planes (eg, direct vertebral derotation/manipulation, Ponte-type posterior column releases) have also contributed to advancements in the radiographic outcomes of surgical correction for scoliosis in the last decade [17-21]. The purpose of this study was to evaluate whether patient-reported outcomes have changed over time in conjunction with the advances in the assessment and correction of AIS. Pre- and postoperative Scoliosis Research Society (SRS)-24 Outcomes Instrument scores were assessed over a 15-year period to identify changes in patient outcomes.
Materials and Methods A query of AIS operative patients from a longitudinal prospective multicenter registry was performed. Data before 2001 were excluded as they comprised !2% of the available patients and were from only 2 of 13 sites. Patients who underwent surgery from 2001 to 2015 with available preoperative and two-year postoperative SRS scores were included. SRS-24 scores were used because of the lack of availability of SRS-22 scores during the early time points of the study period. The entire group was divided into three cohorts based on the observed surgical approach and posterior construct patterns over the 15 years of study. The cohort from 2001e2004 was from a period when anterior approaches were more common and was split 52% anterior instrumentation and 48% posterior instrumentation. Of the posteriors within the 2001e2004 group, 43% were posterior hybrids constructs. The cohort from 2005e2011 covered the time period when the surgeons of the group had largely switched to posterior pedicle screw methods and was 3% anterior instrumentation and 97% posterior instrumentation; of the posteriors, only 5% were hybrid constructs. The most contemporary cohort
was exclusively handled with posterior instrumentation with the most modern correction techniques that focus more on 3D correction. The 2012e2015 cohort contained 0% anterior instrumentation cases, and just 0.2% of the posterior instrumentation cases were hybrids. Because of the ordinal scale (1e5) and bipolar nature of the response sets (positive/negative responses to statements) of the SRS-24, domain/total scores were categorized as <3 (predominantly negative) or 4-5 (predominantly positive). The distributions of the proportion of positive versus negative scores for each of the three cohorts based on the year of surgery were compared with chi-square tests. Radiographic and operative parameters were compared across the three time groups using chi-square or analysis of variance tests as appropriate. Analyses were performed using SPSS v. 24 and alpha was set at p ! .05 to declare significance (IBM Corp., Armonk, NY). Results The query identified 1,719 patients; however, 24 were from before 2001. Thus, 1,695 patients with surgical treatment of AIS were analyzed. Average age was 14.7 2 years, average primary curve magnitude was 54 12 , and the group was primarily female (81%). Patients were from 14 different institutions across North America. There were 172 patients in the years 2001e2004, 926 in the years 2005e2011, and 597 from 2012e2015. SRS-24 scores The percentage of predominantly positive responses (45) at both preoperation and two years postoperation can be seen Figure 1. As Figure 1 demonstrates, there were decreasing percentages of patients with predominantly positive SRS scores preoperatively (4-5) over the three cohorts. This decline in the rate of positive scores is statistically significant for the pain domain (52% in 2001e2004, 44% in 2005e2011, 35% in 2012e2015, p < .001), self-image domain (52% in 2001e2004, 41% in 2005e2011, 36% in 2012e2015, p < .001), and for total score (61% in 2001e2004, 51% in 2005e2011, 45% in 2012e2015, p < .001). Differences approached significance for function (p 5 .06) and activity (p 5 .05). At two years postoperation, there were no significant differences in the distribution of positive versus negative scores across the three time period groups for pain, selfimage, function, activity, or total scores (p O .05, Fig. 1). The SRS-24 also includes three specific postoperative domains, and all three of the postoperative domains demonstrated a significant difference (p ! .05, Fig. 2) over time. For the domain ‘‘Self-image after surgery,’’ the rate of positive scores increased from 29% in 2010e2014, 38% in 2005e2011, to 40% in 2012e2015 (p 5 .023). ‘‘Function after surgery’’ also demonstrated a significant difference in the distribution of scores over the three cohorts, with the
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Fig. 1. Percentage of patients with predominantly positive (O3) SRS-24 scores preoperatively and 2 years postoperatively.
rate of positive scores increasing from 28% in 2001e2004, 28% in 2005e2011, to 35% in 2012e2015 (p 5 .009). Satisfaction with treatment also increased in the rate of positive scores over the cohorts; 83% in 2001e2004, 86% in 2005e2011, to 91% in 2012e2015 (p 5 .006). Demographic, surgical, and deformity measures Age at time of surgery did not differ significantly between the groups (all averaged 15 2 years, p 5 .95; Table 1). Sex was also statistically similar (p 5 .22; Table 2). Rate of follow-up for the cohorts did differ significantly, as did average follow-up between the cohorts (p ! .05; Table 1). However, the average difference in
follow-up, at greatest, was 1 month. As expected, a significant shift in approach was observed over the three time periods, with anterior approach comprising approximately half of the 2001e2004 cohort, to only 3% of the 2005e2011 cohort, and 0% of the final 2012e2015 cohort (p ! .001; Table 2). The percentage of all-screw posterior constructs also increased over the three time periods (p ! .001; Table 2). The length of the fusion similarly increased corresponding with these changes in approach (p ! .001; Table 1). However, length of hospital stay, estimated blood loss as a percentage of blood volume, and surgical time all decreased over the time periods (p ! .05; Table 1). There was a higher rate of cases requiring return Table 1 Continuous patient, curve, and surgical characteristics. 2001e 2004 Follow-up rate, % Average follow-up at time of postoperative SRS collection Age Length of hospital stay Levels fused EBL/BV Surgical time Preoperative Cobb Two-year Cobb Percentage correction Preoperative 3D kyphosis Two-year 3D kyphosis Change in 3D kyphosis Preoperative thoracic rib prominence Two-year thoracic rib prominence Preoperative trunk shift Two-year trunk shift
Fig. 2. Percentage of patients with predominantly positive (O3) scores in the 3 postoperative SRS-24 domains.
2005e 2011
2012e 2015
p value
63 59 55 .009 2.2 0.5 2.3 0.5 2.2 0.4 <.001 15 7 9 28 357 50 21 59 11 25 14 12
2 3 3 33 118 12 8 15 14 10 12 6
15 5 11 23 270 55 20 63 10 25 15 14
2 2 2 20 124 13 9 15 14 9 11 6
15 5 11 18 268 57 20 65 8 26 18 14
2 2 2 13 94 12 8 14 13 8 12 6
64
74
78
22 11
21 0.9 1
2.4 2 0.8 1
EBL/BV, estimated blood loss/blood volume. Bold values represent statistical significance.
.95 <.001 <.001 <.001 <.001 <.001 .56 <.001 .009 .15 <.001 <.001 .95 <.001 .002
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Table 2 Categorical patient, curve, and surgical characteristics. 2001e2004 2005e2011 2012e2015 p value Sex Male Female Lenke class 1 2 3 4 5 6 Curve type Single Double/triple Approach Anterior PSF PSF þ AR Posterior construct type Hook Hybrid Screws Complication requiring return to OR No Yes
16 84
20 80
16 84
.22
57 15 2 0 24 2
41 21 8 4 15 12
43 19 10 5 12 11
!.001
81 19
56 44
55 45
!.001
52 42 6
3 93 4
0 97 3
!.001
2 43 55
0 5 95
0 0.2 99.8
!.001
97 3
93.5 6.5
97 3
.002
AR, anterior release; OR, operating room; PSF, posterior spinal fusion. Values are percentages. Bold p values represent statistical significance.
to the operating room in the middle cohort (3% in 2001e2004, 6.5% in 2005e2011, to 3% in 2012e2015, p 5 .002; Table 2). There was a significant difference in the distribution of Lenke curve types over the three time periods, with the percentage of single curves (Lenke 1 and 5) declining over time (p ! .05; Table 2). The most recent cohort (2012e2015) had significantly larger preoperative primary curves than the earlier two cohorts (p ! .05; Table 1). The middle cohort 2005e2011 also had significantly larger primary curves compared with the first time cohort (p ! .05). At two years postoperatively, the average major curve percentage correction in the two later groups were significantly greater than the 2001e2004 cohort (p ! .001). Estimated 3D T5eT12 kyphosis [22] restoration after surgery increased significantly over time (p ! .001). Preoperative thoracic rib prominence on forward bend was significantly less in the earliest cohort (2001e2004) compared with the subsequent cohorts (p ! .05). The 2012e2015 cohort had the largest average trunk shift preoperatively (p ! .001), but the smallest two years postoperatively (p ! .001; Table 1). Discussion In addition to advancements in the understanding of the 3D deformity of AIS and improvements in the ability to obtain surgical correction in all three planes, patientreported outcomes have also evolved in the last decade.
Although radiographic outcome advancements are critical in improving the treatment of AIS, it is imperative that these improvements also be reflected in the patients’ reporting of their outcomes to deem a treatment efficacious. This is not only important in determining whether the best care is being delivered for the patient, but it can also impact coverage for treatment as payors move toward reimbursement decisions based on concepts such as quality-adjusted life years [23]. In this prospective observational analysis, SRS outcome scores for the three postoperative domains improved over the last 15 years, with the largest improvement noted in the most recent group. This provides indirect evidence that as techniques have changed in the surgical treatment of scoliosis, patient outcomes have improved. Other studies have also found superior patient outcomes with modern constructs or approaches. Smucny et al. observed greater self-reported improvements in appearance scores by patients with all-screw constructs compared with hybrid constructs [24]. Larson et al. found statistically greater outcome scores at two years in patients with high screw density as compared with those with low screw density [25]. However, the authors questioned the clinical relevance of the average difference in scores, and other authors have not been able to demonstrate a difference in outcomes based on surgical approach, constructs, or techniques [2628]. Some of the discrepancy observed in these differences or lack of differences may be attributed to use of different versions of the SRS tool (22 vs. 24) and various methods for analyzing the SRS scores. The scores are often evaluated as averages (continuous) and in some cases are examined as percentages (categorical). The SRS scores are ordinal in nature and thus violate assumptions associated with parametric statistical analyses; as such, a bipolar response set was analyzed for this study. This approach to analyzing ordinal scales has been advocated by other researchers outside the field of scoliosis [29-31]. An unexpected finding in this data set was the progressively lower preoperative SRS scores over time, particularly in the self-image domain. This led to evaluation of the curve characteristics of the three cohorts. The prevalence of single curves (Lenke 1, 5) decreased over time in this study population, while the prevalence of double/triple curve patterns (Lenke 2, 3, 4, and 6) increased. The average curve magnitude of the primary deformity, thoracic rib prominence, and trunk shift also showed a modest, but significant, increase in recent years. Sponseller et al. previously demonstrated that smaller curve sizes were observed in the single curve patterns (Lenke 1, 5) and that Lenke 4 curve types had the largest deformity magnitude [32]. They also showed that the Lenke 4 curve type had lower preoperative self-image scores than the Lenke 1 curve type. However, other studies have examined the relationship between deformity magnitude and patient-reported outcome scores and found weak correlations [33-35]. Thus, it is unclear if there is a direct relationship between the worsening of
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preoperative SRS scores over time and the increase in deformity size observed in this cohort. One other possibility is that the cohorts included here may have been impacted by societal changes that occurred outside of the phenomenon being studied. Significant changes have occurred within society during the last 15 years that could impact an adolescent’s self-image, in particular, the widespread use of social media [36,37]. Although it seems logical to extrapolate that the lower preoperative self-image scores could be associated with the increase in double/triple curve patterns and larger deformities, the question still remains as to how the population has evolved over time. With the data available for analysis, one can only speculate why this might be the case. One possible explanation is evolution in practice patterns of the surgeons contributing cases to the registry, such that they have become subspecialized experts at tertiary referral centers and the complexity of cases within their clinics has increased. Another explanation could be a trend in North American society to embrace alternative therapies as a means of front line medical care, thus referral to specialists is delayed and the curve patterns advanced [38-41]. Alternatively, the advances in scoliosis treatment could themselves be a reason for this increase in larger, more complex curve patterns. The techniques available with allepedicle screw constructs allow for powerful correction of even large, rigid curves [2,3,5,6]. Therefore, surgeons and families may be more confident in allowing a curve to progress before making the decision to proceed with surgery. Lastly, the lower preoperative scores in the contemporary era could be completely unrelated to the scoliotic deformity and be the result of societal and cultural changes over time. The increase in popularity of social media platforms in recent years could potentially contribute to a shift in adolescent females’ perception of self, relative to others. The percentage of patients with positive SRS-24 scores in the three postoperative domains has increased in the modern era, providing evidence that newer surgical techniques are resulting in improved patient outcomes. The cost-benefit ratio for the rate of improvement relative to the need for longer fusions with more costly instrumentation (possibly as a result of more complex, larger curves) still needs to be determined but is beyond the scope of the data gathered in this study. Interestingly, recent patients were more afflicted with negative self-image (lower scores) before surgery. An increase in the rate of double and triple curve patterns, as well as an increase in measures of deformity suggest that this worsened preoperative selfimage score could be attributed to greater scoliotic deformity. To gain an understanding of whether a true cause-andeffect relationship exists between worsening deformity and SRS scores, while also assessing a potential societal impact, would require a long-term, multifaceted study with an epidemiologic component. Despite the limitations, this prospective evaluation of SRS-24 outcome scores over this 15-year period demonstrated an increasing percentage of
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the postoperative patients reporting greater satisfaction with their scoliosis correction using modern posterior pedicle screwebased instrumentation strategies. From the patients’ perspectives, we seem to be doing a better job with the surgical correction of scoliosis recently compared with 15 years ago; however, the data also suggest that despite the advancements, there is room remaining for continued improvement.
Acknowledgments This work was funded in part by research grants to Setting Scoliosis Straight Foundation from DePuy Synthes Spine in support of Harms Study Group research. References [1] Lonner BS, Ren Y, Yaszay B, et al. Evolution of surgery for adolescent idiopathic scoliosis over 20 years: have outcomes improved? Spine (Phila Pa 1976) 2018;43:402e10. [2] Burton DC, Sama AA, Asher MA, et al. The treatment of large (O70 degrees) thoracic idiopathic scoliosis curves with posterior instrumentation and arthrodesis: when is anterior release indicated? Spine (Phila Pa 1976) 2005;30:1979e84. [3] Dobbs MB, Lenke LG, Kim YJ, et al. Anterior/posterior spinal instrumentation versus posterior instrumentation alone for the treatment of adolescent idiopathic scoliotic curves more than 90 degrees. Spine (Phila Pa 1976) 2006;31:2386e91. [4] Hasler CC. A brief overview of 100 years of history of surgical treatment for adolescent idiopathic scoliosis. J Child Orthop 2013;7:57e62. [5] Hee HT, Yu ZR, Wong HK. Comparison of segmental pedicle screw instrumentation versus anterior instrumentation in adolescent idiopathic thoracolumbar and lumbar scoliosis. Spine (Phila Pa 1976) 2007;32:1533e42. [6] Luhmann SJ, Lenke LG, Kim YJ, et al. Thoracic adolescent idiopathic scoliosis curves between 70 degrees and 100 degrees: is anterior release necessary? Spine (Phila Pa 1976) 2005;30:2061e7. [7] Kim YJ, Lenke LG, Cho SK, et al. Comparative analysis of pedicle screw versus hook instrumentation in posterior spinal fusion of adolescent idiopathic scoliosis. Spine (Phila Pa 1976) 2004;29: 2040e8. [8] Kim YJ, Lenke LG, Kim J, et al. Comparative analysis of pedicle screw versus hybrid instrumentation in posterior spinal fusion of adolescent idiopathic scoliosis. Spine (Phila Pa 1976) 2006;31: 291e8. [9] Kuklo TR, Potter BK, Lenke LG, et al. Surgical revision rates of hooks versus hybrid versus screws versus combined anteroposterior spinal fusion for adolescent idiopathic scoliosis. Spine (Phila Pa 1976) 2007;32:2258e64. [10] Suk SI, Kim WJ, Lee SM, et al. Thoracic pedicle screw fixation in spinal deformities: are they really safe? Spine (Phila Pa 1976) 2001;26:2049e57. [11] Suk SI, Lee CK, Kim WJ, et al. Segmental pedicle screw fixation in the treatment of thoracic idiopathic scoliosis. Spine (Phila Pa 1976) 1995;20:1399e405. [12] Yilmaz G, Borkhuu B, Dhawale AA, et al. Comparative analysis of hook, hybrid, and pedicle screw instrumentation in the posterior treatment of adolescent idiopathic scoliosis. J Pediatr Orthop 2012;32:490e9. [13] Delorme S, Labelle H, Poitras B, et al. Pre-, intra-, and postoperative three-dimensional evaluation of adolescent idiopathic scoliosis. J Spinal Disord 2000;13:93e101.
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Patient-Reported SRS-24 Outcomes Scores After Surgery for Adolescent Idiopathic Scoliosis Have Improved Since the New Millennium Tracey P. Bastrom, MAa, Carrie E. Bartley, MAa, Peter O. Newton, MDa,*, Harms Study Groupb a
b
Rady Children’s Hospital, 3020 Children’s Way, San Diego, CA, 92123, USA Setting Scoliosis Straight Foundation, 2535 Camino Del Rio S. Suite 325, San Diego, CA, 92108, USA Received 2 August 2018; revised 5 November 2018; accepted 8 January 2019
Abstract Study Design: Observational. Objective: To examine changes in patient-reported two-year postoperative outcomes via the Scoliosis Research Society (SRS)-24 Outcomes Instrument from 2001 through 2015. Summary of Background Data: Techniques for correction of adolescent idiopathic scoliosis (AIS) have evolved over the years, but it is unclear how these changes have impacted patient-reported outcomes. Methods: AIS patients with two-year postoperative follow-up from a prospective multicenter registry were divided into three-year groups based on trends in surgical approach and construct type (2010e2014: 52% anterior, 43% posterior hybrids; 2005e2011: 3% anterior, 5% posterior hybrids; 2012e2015: 0% anterior, 0.2% posterior hybrids). Because of the ordinal scale (1-5) and bipolar nature of the response sets for the SRS-24, domain/total scores were categorized as <3 (predominantly negative) or 4-5 (predominantly positive). Variables were compared across the three groups. Results: A total of 1,695 patients were analyzed; 172 (2010e2014), 926 (2005e2011), and 597 (2012e2015). Average age was 14.7 2 years, the average primary curve was 55 13 , and the group was primarily female (82%). There was a decline in the rate of positive scores for preoperative pain and self-image across the three groups (p ! .05). There was an increase in the rate of positive scores for twoyear postoperative self-image after surgery, function after surgery, and satisfaction (p ! .05). Decreases in length of hospital stay, blood loss, surgical time, preoperative kyphosis, and postoperative trunk shift were observed (p ! .05). Increases were observed in levels fused, preoperative major coronal curve, preoperative rib prominence, preoperative trunk shift, percentage correction of major curve, kyphosis restoration, and the rate of double/triple curves (p ! .05). Conclusion: The percentage of patients with positive postoperative SRS scores has increased in the modern era, providing evidence that newer surgical techniques are resulting in improved outcomes based on the patients’ perspectives. Interestingly, recent patients were more afflicted with negative pain and self-image before surgery. Ó 2019 Scoliosis Research Society. All rights reserved. Keywords: Patient reported outcomes; Adolescent idiopathic scoliosis; SRS-24; Scoliosis
Author disclosures: TPB (grants from Setting Scoliosis Straight Foundation, during the conduct of the study), CEB (grants from Setting Scoliosis Straight Foundation, during the conduct of the study), PON (grants from Setting Scoliosis Straight Foundation, during the conduct of the study; grants and other from Setting Scoliosis Straight Foundation and Scoliosis Research Society [SRS]; other from Rady Children’s Specialists; grants, personal fees, and nonfinancial support from DePuy Synthes Spine and K2M; grants from EOS Imaging and NuVasive; personal fees from Thieme Publishing and Cubist; other from Electrocore; other from International Pediatric Orthopedic Think Tank; grants, nonfinancial support, and other from Orthopediatrics; grants and nonfinancial support from Alphatech; grants from Mazor Robotics, outside the submitted work; in addition, PON has a patent ‘‘Anchoring Systems and Methods for Correcting Spinal Deformities’’ (8540754) with royalties paid to DePuy Synthes Spine; a patent ‘‘Low Profile Spinal Tethering Systems’’ (8123749) licensed to
DePuy Spine, Inc.; a patent ‘‘Screw Placement Guide’’ (7981117) licensed to DePuy Spine, Inc.; a patent ‘‘Compressor for Use in Minimally Invasive Surgery’’ (7189244) licensed to DePuy Spine, Inc.; and a patent ‘‘Posterior Spinal Fixation’’ pending to K2M), Harms Study Group (grants from DePuy Synthes Spine and EOS Imaging, during the conduct of the study; grants from NuVasive, K2M, Inc., Medtronic, and Zimmer Biomet, outside the submitted work). This study was conducted at Rady Children’s Hospital, San Diego, CA. IRB approval: IRB approval was obtained for this study (approval no. 150406, University of California, San Diego). *Corresponding author. Chief Division of Orthopedics, Department of Orthopedic Surgery, Rady Children’s Hospital, University of California, San Diego, 3030 Children’s Way, MC5062, San Diego, CA, 92123, USA. Tel.: (858) 966-6789; fax: (858) 966-7494. E-mail address: [email protected] (P.O. Newton).
2212-134X/$ - see front matter Ó 2019 Scoliosis Research Society. All rights reserved. https://doi.org/10.1016/j.jspd.2019.01.007
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Introduction Significant changes to the approach, constructs, and intraoperative techniques used for surgical correction of adolescent idiopathic scoliosis (AIS) have been made over the last few decades. Recent data suggest that during the last 20 years, anterior-only approaches for the treatment of AIS have dramatically decreased and allepedicle screw constructs have increased [1]. The shift to using posterior only approaches for all curve types because of their ability to achieve greater correction has been well documented, even for the treatment of larger curves [2-6]. This tendency toward posterior-only correction can largely be attributed to the efficacy of pedicle screw constructs [7-12]. Along with these changes, the ability to assess and measure the true scoliotic deformity in three dimensions (3D) has been enhanced with the introduction of technology that allows 3D reconstruction of the spine with low radiation exposure [13-16]. This greater understanding of the true 3D deformity and the use of other intraoperative methods to improve correction in all three planes (eg, direct vertebral derotation/manipulation, Ponte-type posterior column releases) have also contributed to advancements in the radiographic outcomes of surgical correction for scoliosis in the last decade [17-21]. The purpose of this study was to evaluate whether patient-reported outcomes have changed over time in conjunction with the advances in the assessment and correction of AIS. Pre- and postoperative Scoliosis Research Society (SRS)-24 Outcomes Instrument scores were assessed over a 15-year period to identify changes in patient outcomes.
Materials and Methods A query of AIS operative patients from a longitudinal prospective multicenter registry was performed. Data before 2001 were excluded as they comprised !2% of the available patients and were from only 2 of 13 sites. Patients who underwent surgery from 2001 to 2015 with available preoperative and two-year postoperative SRS scores were included. SRS-24 scores were used because of the lack of availability of SRS-22 scores during the early time points of the study period. The entire group was divided into three cohorts based on the observed surgical approach and posterior construct patterns over the 15 years of study. The cohort from 2001e2004 was from a period when anterior approaches were more common and was split 52% anterior instrumentation and 48% posterior instrumentation. Of the posteriors within the 2001e2004 group, 43% were posterior hybrids constructs. The cohort from 2005e2011 covered the time period when the surgeons of the group had largely switched to posterior pedicle screw methods and was 3% anterior instrumentation and 97% posterior instrumentation; of the posteriors, only 5% were hybrid constructs. The most contemporary cohort
was exclusively handled with posterior instrumentation with the most modern correction techniques that focus more on 3D correction. The 2012e2015 cohort contained 0% anterior instrumentation cases, and just 0.2% of the posterior instrumentation cases were hybrids. Because of the ordinal scale (1e5) and bipolar nature of the response sets (positive/negative responses to statements) of the SRS-24, domain/total scores were categorized as <3 (predominantly negative) or 4-5 (predominantly positive). The distributions of the proportion of positive versus negative scores for each of the three cohorts based on the year of surgery were compared with chi-square tests. Radiographic and operative parameters were compared across the three time groups using chi-square or analysis of variance tests as appropriate. Analyses were performed using SPSS v. 24 and alpha was set at p ! .05 to declare significance (IBM Corp., Armonk, NY). Results The query identified 1,719 patients; however, 24 were from before 2001. Thus, 1,695 patients with surgical treatment of AIS were analyzed. Average age was 14.7 2 years, average primary curve magnitude was 54 12 , and the group was primarily female (81%). Patients were from 14 different institutions across North America. There were 172 patients in the years 2001e2004, 926 in the years 2005e2011, and 597 from 2012e2015. SRS-24 scores The percentage of predominantly positive responses (45) at both preoperation and two years postoperation can be seen Figure 1. As Figure 1 demonstrates, there were decreasing percentages of patients with predominantly positive SRS scores preoperatively (4-5) over the three cohorts. This decline in the rate of positive scores is statistically significant for the pain domain (52% in 2001e2004, 44% in 2005e2011, 35% in 2012e2015, p < .001), self-image domain (52% in 2001e2004, 41% in 2005e2011, 36% in 2012e2015, p < .001), and for total score (61% in 2001e2004, 51% in 2005e2011, 45% in 2012e2015, p < .001). Differences approached significance for function (p 5 .06) and activity (p 5 .05). At two years postoperation, there were no significant differences in the distribution of positive versus negative scores across the three time period groups for pain, selfimage, function, activity, or total scores (p O .05, Fig. 1). The SRS-24 also includes three specific postoperative domains, and all three of the postoperative domains demonstrated a significant difference (p ! .05, Fig. 2) over time. For the domain ‘‘Self-image after surgery,’’ the rate of positive scores increased from 29% in 2010e2014, 38% in 2005e2011, to 40% in 2012e2015 (p 5 .023). ‘‘Function after surgery’’ also demonstrated a significant difference in the distribution of scores over the three cohorts, with the
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Fig. 1. Percentage of patients with predominantly positive (O3) SRS-24 scores preoperatively and 2 years postoperatively.
rate of positive scores increasing from 28% in 2001e2004, 28% in 2005e2011, to 35% in 2012e2015 (p 5 .009). Satisfaction with treatment also increased in the rate of positive scores over the cohorts; 83% in 2001e2004, 86% in 2005e2011, to 91% in 2012e2015 (p 5 .006). Demographic, surgical, and deformity measures Age at time of surgery did not differ significantly between the groups (all averaged 15 2 years, p 5 .95; Table 1). Sex was also statistically similar (p 5 .22; Table 2). Rate of follow-up for the cohorts did differ significantly, as did average follow-up between the cohorts (p ! .05; Table 1). However, the average difference in
follow-up, at greatest, was 1 month. As expected, a significant shift in approach was observed over the three time periods, with anterior approach comprising approximately half of the 2001e2004 cohort, to only 3% of the 2005e2011 cohort, and 0% of the final 2012e2015 cohort (p ! .001; Table 2). The percentage of all-screw posterior constructs also increased over the three time periods (p ! .001; Table 2). The length of the fusion similarly increased corresponding with these changes in approach (p ! .001; Table 1). However, length of hospital stay, estimated blood loss as a percentage of blood volume, and surgical time all decreased over the time periods (p ! .05; Table 1). There was a higher rate of cases requiring return Table 1 Continuous patient, curve, and surgical characteristics. 2001e 2004 Follow-up rate, % Average follow-up at time of postoperative SRS collection Age Length of hospital stay Levels fused EBL/BV Surgical time Preoperative Cobb Two-year Cobb Percentage correction Preoperative 3D kyphosis Two-year 3D kyphosis Change in 3D kyphosis Preoperative thoracic rib prominence Two-year thoracic rib prominence Preoperative trunk shift Two-year trunk shift
Fig. 2. Percentage of patients with predominantly positive (O3) scores in the 3 postoperative SRS-24 domains.
2005e 2011
2012e 2015
p value
63 59 55 .009 2.2 0.5 2.3 0.5 2.2 0.4 <.001 15 7 9 28 357 50 21 59 11 25 14 12
2 3 3 33 118 12 8 15 14 10 12 6
15 5 11 23 270 55 20 63 10 25 15 14
2 2 2 20 124 13 9 15 14 9 11 6
15 5 11 18 268 57 20 65 8 26 18 14
2 2 2 13 94 12 8 14 13 8 12 6
64
74
78
22 11
21 0.9 1
2.4 2 0.8 1
EBL/BV, estimated blood loss/blood volume. Bold values represent statistical significance.
.95 <.001 <.001 <.001 <.001 <.001 .56 <.001 .009 .15 <.001 <.001 .95 <.001 .002
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Table 2 Categorical patient, curve, and surgical characteristics. 2001e2004 2005e2011 2012e2015 p value Sex Male Female Lenke class 1 2 3 4 5 6 Curve type Single Double/triple Approach Anterior PSF PSF þ AR Posterior construct type Hook Hybrid Screws Complication requiring return to OR No Yes
16 84
20 80
16 84
.22
57 15 2 0 24 2
41 21 8 4 15 12
43 19 10 5 12 11
!.001
81 19
56 44
55 45
!.001
52 42 6
3 93 4
0 97 3
!.001
2 43 55
0 5 95
0 0.2 99.8
!.001
97 3
93.5 6.5
97 3
.002
AR, anterior release; OR, operating room; PSF, posterior spinal fusion. Values are percentages. Bold p values represent statistical significance.
to the operating room in the middle cohort (3% in 2001e2004, 6.5% in 2005e2011, to 3% in 2012e2015, p 5 .002; Table 2). There was a significant difference in the distribution of Lenke curve types over the three time periods, with the percentage of single curves (Lenke 1 and 5) declining over time (p ! .05; Table 2). The most recent cohort (2012e2015) had significantly larger preoperative primary curves than the earlier two cohorts (p ! .05; Table 1). The middle cohort 2005e2011 also had significantly larger primary curves compared with the first time cohort (p ! .05). At two years postoperatively, the average major curve percentage correction in the two later groups were significantly greater than the 2001e2004 cohort (p ! .001). Estimated 3D T5eT12 kyphosis [22] restoration after surgery increased significantly over time (p ! .001). Preoperative thoracic rib prominence on forward bend was significantly less in the earliest cohort (2001e2004) compared with the subsequent cohorts (p ! .05). The 2012e2015 cohort had the largest average trunk shift preoperatively (p ! .001), but the smallest two years postoperatively (p ! .001; Table 1). Discussion In addition to advancements in the understanding of the 3D deformity of AIS and improvements in the ability to obtain surgical correction in all three planes, patientreported outcomes have also evolved in the last decade.
Although radiographic outcome advancements are critical in improving the treatment of AIS, it is imperative that these improvements also be reflected in the patients’ reporting of their outcomes to deem a treatment efficacious. This is not only important in determining whether the best care is being delivered for the patient, but it can also impact coverage for treatment as payors move toward reimbursement decisions based on concepts such as quality-adjusted life years [23]. In this prospective observational analysis, SRS outcome scores for the three postoperative domains improved over the last 15 years, with the largest improvement noted in the most recent group. This provides indirect evidence that as techniques have changed in the surgical treatment of scoliosis, patient outcomes have improved. Other studies have also found superior patient outcomes with modern constructs or approaches. Smucny et al. observed greater self-reported improvements in appearance scores by patients with all-screw constructs compared with hybrid constructs [24]. Larson et al. found statistically greater outcome scores at two years in patients with high screw density as compared with those with low screw density [25]. However, the authors questioned the clinical relevance of the average difference in scores, and other authors have not been able to demonstrate a difference in outcomes based on surgical approach, constructs, or techniques [2628]. Some of the discrepancy observed in these differences or lack of differences may be attributed to use of different versions of the SRS tool (22 vs. 24) and various methods for analyzing the SRS scores. The scores are often evaluated as averages (continuous) and in some cases are examined as percentages (categorical). The SRS scores are ordinal in nature and thus violate assumptions associated with parametric statistical analyses; as such, a bipolar response set was analyzed for this study. This approach to analyzing ordinal scales has been advocated by other researchers outside the field of scoliosis [29-31]. An unexpected finding in this data set was the progressively lower preoperative SRS scores over time, particularly in the self-image domain. This led to evaluation of the curve characteristics of the three cohorts. The prevalence of single curves (Lenke 1, 5) decreased over time in this study population, while the prevalence of double/triple curve patterns (Lenke 2, 3, 4, and 6) increased. The average curve magnitude of the primary deformity, thoracic rib prominence, and trunk shift also showed a modest, but significant, increase in recent years. Sponseller et al. previously demonstrated that smaller curve sizes were observed in the single curve patterns (Lenke 1, 5) and that Lenke 4 curve types had the largest deformity magnitude [32]. They also showed that the Lenke 4 curve type had lower preoperative self-image scores than the Lenke 1 curve type. However, other studies have examined the relationship between deformity magnitude and patient-reported outcome scores and found weak correlations [33-35]. Thus, it is unclear if there is a direct relationship between the worsening of
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preoperative SRS scores over time and the increase in deformity size observed in this cohort. One other possibility is that the cohorts included here may have been impacted by societal changes that occurred outside of the phenomenon being studied. Significant changes have occurred within society during the last 15 years that could impact an adolescent’s self-image, in particular, the widespread use of social media [36,37]. Although it seems logical to extrapolate that the lower preoperative self-image scores could be associated with the increase in double/triple curve patterns and larger deformities, the question still remains as to how the population has evolved over time. With the data available for analysis, one can only speculate why this might be the case. One possible explanation is evolution in practice patterns of the surgeons contributing cases to the registry, such that they have become subspecialized experts at tertiary referral centers and the complexity of cases within their clinics has increased. Another explanation could be a trend in North American society to embrace alternative therapies as a means of front line medical care, thus referral to specialists is delayed and the curve patterns advanced [38-41]. Alternatively, the advances in scoliosis treatment could themselves be a reason for this increase in larger, more complex curve patterns. The techniques available with allepedicle screw constructs allow for powerful correction of even large, rigid curves [2,3,5,6]. Therefore, surgeons and families may be more confident in allowing a curve to progress before making the decision to proceed with surgery. Lastly, the lower preoperative scores in the contemporary era could be completely unrelated to the scoliotic deformity and be the result of societal and cultural changes over time. The increase in popularity of social media platforms in recent years could potentially contribute to a shift in adolescent females’ perception of self, relative to others. The percentage of patients with positive SRS-24 scores in the three postoperative domains has increased in the modern era, providing evidence that newer surgical techniques are resulting in improved patient outcomes. The cost-benefit ratio for the rate of improvement relative to the need for longer fusions with more costly instrumentation (possibly as a result of more complex, larger curves) still needs to be determined but is beyond the scope of the data gathered in this study. Interestingly, recent patients were more afflicted with negative self-image (lower scores) before surgery. An increase in the rate of double and triple curve patterns, as well as an increase in measures of deformity suggest that this worsened preoperative selfimage score could be attributed to greater scoliotic deformity. To gain an understanding of whether a true cause-andeffect relationship exists between worsening deformity and SRS scores, while also assessing a potential societal impact, would require a long-term, multifaceted study with an epidemiologic component. Despite the limitations, this prospective evaluation of SRS-24 outcome scores over this 15-year period demonstrated an increasing percentage of
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the postoperative patients reporting greater satisfaction with their scoliosis correction using modern posterior pedicle screwebased instrumentation strategies. From the patients’ perspectives, we seem to be doing a better job with the surgical correction of scoliosis recently compared with 15 years ago; however, the data also suggest that despite the advancements, there is room remaining for continued improvement.
Acknowledgments This work was funded in part by research grants to Setting Scoliosis Straight Foundation from DePuy Synthes Spine in support of Harms Study Group research. References [1] Lonner BS, Ren Y, Yaszay B, et al. Evolution of surgery for adolescent idiopathic scoliosis over 20 years: have outcomes improved? Spine (Phila Pa 1976) 2018;43:402e10. [2] Burton DC, Sama AA, Asher MA, et al. The treatment of large (O70 degrees) thoracic idiopathic scoliosis curves with posterior instrumentation and arthrodesis: when is anterior release indicated? Spine (Phila Pa 1976) 2005;30:1979e84. [3] Dobbs MB, Lenke LG, Kim YJ, et al. Anterior/posterior spinal instrumentation versus posterior instrumentation alone for the treatment of adolescent idiopathic scoliotic curves more than 90 degrees. Spine (Phila Pa 1976) 2006;31:2386e91. [4] Hasler CC. A brief overview of 100 years of history of surgical treatment for adolescent idiopathic scoliosis. J Child Orthop 2013;7:57e62. [5] Hee HT, Yu ZR, Wong HK. Comparison of segmental pedicle screw instrumentation versus anterior instrumentation in adolescent idiopathic thoracolumbar and lumbar scoliosis. Spine (Phila Pa 1976) 2007;32:1533e42. [6] Luhmann SJ, Lenke LG, Kim YJ, et al. Thoracic adolescent idiopathic scoliosis curves between 70 degrees and 100 degrees: is anterior release necessary? Spine (Phila Pa 1976) 2005;30:2061e7. [7] Kim YJ, Lenke LG, Cho SK, et al. Comparative analysis of pedicle screw versus hook instrumentation in posterior spinal fusion of adolescent idiopathic scoliosis. Spine (Phila Pa 1976) 2004;29: 2040e8. [8] Kim YJ, Lenke LG, Kim J, et al. Comparative analysis of pedicle screw versus hybrid instrumentation in posterior spinal fusion of adolescent idiopathic scoliosis. Spine (Phila Pa 1976) 2006;31: 291e8. [9] Kuklo TR, Potter BK, Lenke LG, et al. Surgical revision rates of hooks versus hybrid versus screws versus combined anteroposterior spinal fusion for adolescent idiopathic scoliosis. Spine (Phila Pa 1976) 2007;32:2258e64. [10] Suk SI, Kim WJ, Lee SM, et al. Thoracic pedicle screw fixation in spinal deformities: are they really safe? Spine (Phila Pa 1976) 2001;26:2049e57. [11] Suk SI, Lee CK, Kim WJ, et al. Segmental pedicle screw fixation in the treatment of thoracic idiopathic scoliosis. Spine (Phila Pa 1976) 1995;20:1399e405. [12] Yilmaz G, Borkhuu B, Dhawale AA, et al. Comparative analysis of hook, hybrid, and pedicle screw instrumentation in the posterior treatment of adolescent idiopathic scoliosis. J Pediatr Orthop 2012;32:490e9. [13] Delorme S, Labelle H, Poitras B, et al. Pre-, intra-, and postoperative three-dimensional evaluation of adolescent idiopathic scoliosis. J Spinal Disord 2000;13:93e101.
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