Eur Spine J DOI 10.1007/s00586-014-3593-3
REVIEW ARTICLE
Quality of life outcomes in surgically treated adult scoliosis patients: a systematic review Jennifer Theis • Paul Gerdhem • Allan Abbott
Received: 5 March 2014 / Revised: 20 September 2014 / Accepted: 21 September 2014 Ó Springer-Verlag Berlin Heidelberg 2014
Abstract Purpose The aim of this systematic review was to identify prospective studies reporting the impact of surgical intervention on health-related quality of life (HRQL) outcomes for adults with scoliosis at a minimum 2 year follow-up. Method An electronic database search was conducted for January 2000–November 2013 in conjunction with a reference list search of two related systematic reviews for prospective studies of adults with scoliosis reporting HRQL outcome measure. Methodological quality of included articles was assessed using the Downs and Black checklist. Cohen’s d effect size was calculated for Scoliosis Research Society Questionnaire (SRS) and Oswestry Disability Index (ODI) outcomes for included studies and pooled data.
J. Theis (&) A. Abbott Department of Clinical and Rehabilitation Services, Faculty of Health Science and Medicine, Bond Institute of Health and Sport, Bond University, 2 Promethean Way, Robina, QLD 4226, Australia e-mail: [email protected] P. Gerdhem Department of Orthopaedics, Department of Clinical Science, Intervention and Technology (CLINTEC), Karolinska Institutet, Karolinska University Hospital, 141 86 Stockholm, Sweden A. Abbott Department of Physical Therapy, Karolinska University Hospital, 141 86 Stockholm, Sweden A. Abbott Division of Physiotherapy, Department of Neurobiology, Care Sciences and Society, Karolinska Institutet, 141 86 Stockholm, Sweden
Results The database and reference list searches returned 349 potential articles; three articles met the inclusion criteria. Downs and Black scores ranged from 18/28 to 21/28 (fair–good quality evidence). Total number of 188 patients were treated surgically and had a mean age of 38 years or older. All studies showed significant improvement in reported HRQL outcomes for at least a 2 year follow-up. The Cohen’s d effect size for SRS was d = 1.4 (n = 188, 95 % CI; 0.9, 1.8) and for ODI d = 0.9 (n = 120, 95 % CI; 0.4, 1.4). Conclusion Findings from this review suggest surgery improves HRQL in patients with adult scoliosis at a minimum 2 year follow-up. However, these findings are based on limited data of fair to good quality which needs to be taken into consideration when interpreting the results and highlights the need for additional high quality prospective studies. Keywords Adult Scoliosis Surgery Quality of life Scoliosis Research Society Oswestry Disability Index
Introduction While scoliosis is often associated with childhood and adolescence, increased life expectancy and demographic shifts suggest increasing need for investigations focused on adult scoliosis [1, 2]. Reported prevalence rates of adult scoliosis vary widely in the literature from 9 % [3] to 68 % [1], with increased prevalence associated with older age [3]. Adult scoliosis, a spinal deformity defined as a coronal plane Cobb angle [10° [4] in the skeletally mature patient [2, 5], has two primary pathogeneses; idiopathic scoliosis and degenerative scoliosis [2, 5, 6]. Adult idiopathic scoliosis is associated with a progression or secondary spinal
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degeneration stemming from childhood or adolescent idiopathic scoliosis while adult degenerative scoliosis develops without a prior history of scoliosis, often from degenerative changes to intervertebral discs and facet joints adversely affecting a motion segment [2, 5–7]. Both types lead to asymmetric degeneration, loading, and deformity of the spine interacting in an often progressive cycle [2, 5, 6]. The degenerative and progressive nature of adult scoliosis often results in spinal segment instability, spondyloarthritis, spondylosis, and spinal stenosis [2, 5–7]. Clinically, adult scoliosis manifests as back pain, radicular pain, claudication symptoms, and curve progression, with indications for treatment stemming from disability and pain [2, 6–8]. Considering the associated disability and pain, treatment goals should include improving quality of life and decreasing pain [8]. While nonsurgical intervention is a first treatment option, a systematic review of this approach found insufficient evidence to support nonoperative management of adult scoliosis [9], and a further study found no significant improvement in Oswestry Disability Index (ODI), numeric rating scale (NRS), or Scoliosis Research Society Questionnaire-22 (SRS-22) measures for patients with scoliosis-related back pain treated with nonoperative intervention at 2 year follow-up [10]. However, surgery in the adult scoliosis patient is complicated by their more ridged curves, co-morbidities, and increased spinal degenerative changes requiring more extensive surgical intervention compared to adolescent idiopathic scoliosis [6] and has been associated with higher complication rates (13.4 % in adults [11] compared with 5.7 % in adolescents [12]) based on review of the Scoliosis Research Society morbidity and mortality database. Despite this, two recent systematic reviews suggest operative interventions for adult scoliosis yield significant improvement in clinical outcomes and radiographic improvements along with the need to consider the high rate of complications [13, 14]. Yadla et al. [13] evaluated articles related to adult scoliosis or adult spinal deformity, possibly including other causes in addition to scoliosis. Additionally, by including studies with participant mean age of [18 years at time of surgery they reviewed studies incorporating adult and adolescent scoliosis [13]. Liang et al. [14] and Yadla et al. [13] included prospective and retrospective studies rated as low to moderate quality evidence and included studies that did not report health-related quality of life (HRQL) data. The aim of this review is to determine, through systematic evaluation of prospective research studies, if surgical intervention for a primary diagnosis of adult scoliosis has a significant improvement on HRQL outcome measures at a minimum 2 year follow-up; radiographic changes and complication rate will also be evaluated.
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Methods Literature review A search of seven electronic databases, PubMed, CINAHL, EMBASE, Web of Knowledge, PEDro, The Cochrane Library, and PsycINFO, was conducted in November 2013 to locate potential articles using search terms and filters relevant to each database along with a reference list search of two recent systematic reviews [13, 14] (retrieved through a PubMed search). The databases, search terms, filters, and results of the search are outlined in Table 1. Inclusion criteria were: (1) primary diagnosis of adult scoliosis, (2) age C18 years old at time of surgery, (3) HRQL outcome measure reported at baseline and final follow-up, (4) follow-up C2 years, (5) prospective study (randomized control trial, clinical trial, quasi-randomized trial), and (6) full text available in English. Exclusion criteria were: studies of spinal deformity primarily attributed to a condition other than scoliosis (e.g., kyphosis, spondylolisthesis, or spinal stenosis) or scoliosis resulting from a neuromuscular condition, osteopenia, traumatic injury, or not specified. Critical appraisal The Downs and Black checklist, 27 item checklist to evaluate the methodological quality of randomized and nonrandomized studies with health care interventions [15], was used to evaluate the included studies. The checklist provides assessment parameters for five main areas, including study reporting, external validity, internal validity, bias and confounding, and statistical power [15] and has been evaluated as a suitable quality assessment tools for use in systematic reviews [16, 17]. For the external validity subscales, the general population was considered to be that of the hospital/specialist treating adults with spinal deformity; thus, the participants in these studies are representative of that population. The tool was modified for use in this review, as in previous reviews, regarding scoring the question concerning statistical power to 1 if a power or sample size calculation was present and 0 if no power or sample size calculation was present [18–21]. The Downs and Black scores are divided into four quality categories: excellent (26–28), good (20–25), fair (15–19), and poor (B14); only a randomized control trial can obtain the top score of 28 [20, 21]. All studies were independently rated by two reviewers (JT and AA) with complete agreement between raters. Statistical analysis Statistical calculations were done using Microsoft Excel (Excel 2010, Microsoft). Prior to statistical analysis, SRS
20
3 3 6
2 10 12 88
2 5 7 85
2 3 5 86
11 11 84
0
Total number satisfying assessment criteria
scores reported with different SRS (SRS-24, SRS-29, and SRS-30) instruments were converted to SRS-22r scores. The raw data containing individual responses to questions on the SRS-24/29/30 was obtained from Rose et al. [22]. For raw data reported using the SRS-24, the conversion algorithm (SRS-22r = 0.956 ? 0.782 9 SRS-24) [23] was applied. The raw data that was in SRS-29 and SRS-30 formats was recalculated directly to SRS-22r scores. Cohen’s d effect sizes was calculated for pre–post data using the pre- and post-mean scores and standard deviations using an online calculator [24]. Microsoft Excel meta-analysis algorithms using a random effects model [25] were used to map out individual study effect size and 95 % confidence interval (CI) data as well as pooled data for the included studies for SRS-22 and ODI.
Literature review Electronic database and secondary reference list searches yielded 349 potential articles. After abstract and title review and removal of duplicates, 20 articles were retrieved in full text (Fig. 1). After full text review, 6 articles met the inclusion criteria; however, four articles [26–29] had population duplication through the use of the Adult Deformity Outcome section of the Spinal Deformity Study Group database with similar recruitment time periods or insufficient information to determine extent of participant overlap. Full text of these articles was further reviewed and the one best matching the inclusion criteria was kept, resulting in 3 articles for inclusion in this review (Fig. 1). One study compared surgical treatment to nonoperative interventions [26], one study compared two different surgical procedures [22], and one study compared baseline to 2 year follow-up of a relatively homogenous cohort [30]. Critical appraisal
Total number of articles retrieved for full text
PEDro, The Cochrane Library, and PsycINFO (search 09.11.2013) with same search strategy—no additional articles17
2000–2013 english article Quality of life AND outcome AND surgery AND adult AND (scoliosis OR spine deformity) 4. Web of knowledge 09.11.2013
5. Secondary reference list search of systematic reviews [13, 14]
2001–2013 human article Quality of life AND outcome AND surgery AND adult AND (scoliosis or spine deformity) 3. EMBASE 09.11.2013
107
2000–2013 english human peer reviewed Quality of life AND outcome AND surgery AND adult AND (scoliosis or spine deformity) 2. CINAHL 09.11.2013
143
2000–2013 english humans Quality of life AND outcome AND surgery AND adult AND (scoliosis or spine deformity) 1. PubMed 09.11.2013
147
Filters used Search terms
110
Results
Database and date of search
Table 1 Details of literature search: databases used, search terms, and inclusion filters
Number prior to applying filters
Number after application of filters
Duplicated
Number of new articles not included in previous searches
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Table 2 summarizes the patient population, study design, findings, and critical appraisal, including Downs and Black scores for the three articles. Two articles were of fair quality of evidence, with scores of 19/28 [26] and 18/28 [22]; the third study was of good quality of evidence scoring 21/28 [30]. All of the studies were prospective cohort studies involving surgical intervention, thus precluding blinding and randomizing of the participants and concealment from the staff. This resulted in low scores for the internal validity bias subscales of the Downs and
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Literature Search of Databases
PubMed 84
CINAHL 86
Reference list search 6
EMBASE 85
Web of Knowledge 88
Potentially relevant articles 349
Exclusions Articles excluded based on title/abstract and duplication 329
Articles retrieved in full text 20
Articles not meeting inclusion criteria 14 Articles meeting inclusion criteria 6
Articles excluded for study population duplication 3 Articles included for review 3 Fig. 1 Flowchart of the literature review process
Black. Additionally, none of the authors discussed power or if their studies indicated a clinically meaningful effect. Not assessed on the Downs and Black, but of note as a potential source of bias, Bridwell et al. [26] disclosed that the multicenter Spinal Deformity Study Group database receives industry funding.
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Participants and interventions The number of participants ranged from 35 [30] to 160 (85 treated operatively) [26] with mean age of 38 years or older. Females were more frequent than males [22, 30]; however, sex distribution was not reported in one of the
Consecutively enrolled between 2002–2005 n = 75 treated nonoperatively
Adult symptomatic lumbar scoliosis
Double major scoliosis, thoracolumbar and lumbar curves, lumbar curve had to be as large as thoracic curve
n = 85 treated operatively
Primary case, no prior surgical intervention
Distally fused to sacrum or lumbar
Proximally fused to upper thoracic
Other without medication.
Age range 40–80 years
Medication plus (physiotherapy and/or injections)
Medication
Observation
Prospective cohort study
n = 160
Bridwell et al. [26]
Study design and intervention
Patient population
References
Numerical Rating Scale back pain and leg pain scores (NRS, 0–10)
Oswestry Disability Index
Secondary
2 year
1 year
2 months
Operative
Downs and Black Score = 19, fair quality of evidence
Significant improvement
Significantly better in operative than nonoperative
NRS Back and Leg
Significantly better in operative than nonoperative
ODI
Insignificant difference between minor and major complication groups
No discussion of power
45 % of nonoperative group lost at follow-up
Age (40-59 years old and 60-80 old): no significant difference between age groups Minor and major surgical complications:
Nonoperative treatment compliance not reported
Operative: significant improvement
Nonoperative: no significant change
6 months 1 year 2 year
No information on patient sex
SRS QOL subscores
Nonoperative
Critical appraisal and Downs and Black score Representativeness not reported
Result
Only 2 year follow-up results reported
Pre-treatment baseline
Scoliosis Research Society Quality of Life subscore (SRS QOL)
Measurement intervals
Primary
Outcome measures
Table 2 Summary and critical appraisal of included articles in this review
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123 Thoracic kyphosis: significant decrease in pedicle screw group compared to hook/hybrid
Sagittal plane correction
Primary case, no prior surgical intervention
31 females, 3 males
Mean age 38.1 ± 12 years
29 females, 5 males
Mean age 38.3 ± 13 years
Significant improvement for both cohorts
SRS scores
2 year follow-up
Revision rate: significantly more in hook/hybrid than pedicle screw
Estimated blood loss: no significant difference Operative time: significantly more in hook/hybrid group than pedicle screw group
Operative parameters or revision rate
SRS scores at 2 year follow-up
Coronal plane correction Significantly more in pedicle screw cohort than hook/hybrid cohort
Final follow-up
Result
Hook/hybrid consructs:
Scoliosis Research Society (SRS) scores, varying versions (SRS-24, SRS-29, SRS-30) converted to percentages
Minimum 2 year follow-up (mean 36 months, range 2–6 years)
Pre-operative baseline
Measurement intervals
Lumbar lordosis and sagittal balance: no significant change between groups
Average levels fused = 10.1
n = 34 Hook/ hybrid constructs
Operative parameters or revision rate
Radiographic measures of coronal and sagittal plane
Outcome measures
Pedicle screw instrumentation:
Single thoracic, double thoracic, double major, thoracolumbar, lumbar curves
n = 34 Pedicle screw instrumentation
Idiopathic scoliosis
Average levels fused = 9.7
Prospective matched cohort study
n = 68
Rose et al. [22]
Study design and intervention
Patient population
References
Table 2 continued
Downs and Black Score = 18, fair quality of evidence
No discussion of power
Recruitment timeframe not indicated
Follow-up range not reported
Inconsistent reporting of actual probability values
Patient characteristics lost to follow-up not reported
Critical appraisal and Downs and Black score
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Improvement remained significant at final follow-up
Significant improved at initial follow-up Peaking at 2 year follow-up
SRS-22
Significant improvements at initial follow-up
ODI and SF-36
49 % (17/35 patients)
(final follow-up)
Complication rate
No prior surgical intervention, exception simple decompression procedures
Final follow-up at least 2 years (49.4 ± 17.7 months)
No significant difference between interventions
Significant for all curve types
Coronal correction (final followup)
Result
Little change from initial to final follow-up
Scoliosis Research Society 22 (SRS-22)
Short Form 36 (SF-36)
Follow-ups beginning 6 weeks post-surgery
Pre-operative baseline
Measurement intervals
33 women, 2 men
Mean age 56.3 ± 11.0 years
Number with sacral fusion = 20
Double major, thoracolumbar curves
Complication rate
Surgery between 2000–2006 Oswestry Disability Index (ODI)
Coronal correction
Outcome measures
Prospective cohort study
Mean levels fused = 10 ± 2.8
n = 35
Zimmerman et al. [30]
Study design and intervention
Scoliosis, excluding a more severe spinal abnormality (e.g. stenosis, kyphosis, etc.)
Patient population
References
Table 2 continued
Downs and Black Score = 21, good quality of evidence
No discussion of power
Patient characteristics lost to follow-up not reported
Critical appraisal and Downs and Black score
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Adult symptomatic scoliosis
Idiopathic scoliosis
Scoliosis, excluding a more severe spinal abnormality (e.g., stenosis, kyphosis, etc.)
Bridwell et al. [26]
Rose et al. [22]
Zimmerman et al. [30]
4 ± 1.5
C2
2
Followup (years)
64 ± 24/ 46 ± 16*
Not reported
34 ± 15/ 20 ± 16a
ODI (baseline/ follow-up) (mean ± SD)
SRS: 2.21 (1.72, 2.70)
Selfimage 2.1 ± 0.6/ 3.3 ± 0.7e,*
Satisfaction 1.6 ± 1.2/ 2.9 ± 0.5e,*
Activity 2.5 ± 0.36/ 3.2 ± 0.3d,* Mental health 2.0 ± 0.5/ 3.1 ± 0.2e,*
49° ± 16°/ 20° ± 9°*
ODI: 0.88 (0.56, 1.19)
Pain 2.3 ± 0.4/ 3.3 ± 0.4e,*
f
e
d
c
b
a
Revision rate
SRS-22
Significance compared to hook/hybrid group at final follow-up, of P \ 0.05
SRS-24, SRS-29, SRS-30 converted by authors to percentages for comparison
SRS-QOL subscore
Values for surgical group, significance compared to nonoperative group at 2 year follow-up, P \ 0.05
* Significance compared to baseline, P \ 0.05
56° ± 11°/ 26° ± 11°d,* 63° ± 16°/ 38° ± 18°
SRS: 0.80 (0.50, 1.10)
56° ± 15°/ 27° ± 13°a,*
Major curve (°) (baseline/followup) (mean ± SD)
SRS: 1.41 (1.01, 1.80)
69 % ± 10 %/ 79 % ± 13 %*c
71 % ± 10 %/ 80 % ± 13 %*c
ODI: 0.89 (0.69, 1.09)
3.1 ± 0.5b/ 3.8 ± 0.7*ab SRS: 1.15 (0.92, 1.38)
HRQL pre–post effect size (Cohen’s d, 95 % CI)
SRS score (baseline/followup) (mean ± SD)
ODI Oswestry Disability Index, SRS Scoliosis Research Society Quality of Life scores, HRQL health-related quality of life outcome measure
56 ± 11
38 ± 12
34 (hook/hybrid) (68) 35 (35)
38 ± 13
40–80
Age (years) (range or mean ± SD)
34 (pedicle)
85 (160)
Total number of participants in surgical cohort(s) (total number participates)
Mean ± SD included where reported by author
Diagnosis
References
Table 3 Summary of surgical outcomes from the three articles included in review
17/35
9/58f
1/34f
30/85
Number of complications/ number of cases
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studies [26]. No prior surgical intervention, except possibly a simple decompression procedure [22, 26, 30], was an inclusion criteria in each of the studies, suggesting a degree of homogeneity across all study participants. Description of surgical interventions varied across the studies rendering it difficult to make a direct comparison (Table 2). Bridwell et al. [26] reported level of fusion, Rose et al. [22] reported pedicle screw compared with hook/hybrid instrumentation, and Zimmerman et al. [30] reported on surgical intervention based on anterior, posterior, or combined approach and staging.
Bridwell et al 2009 Rose et al 2009, pedicle surgery cohort Rose et al 2009, hook/hybrid surgery cohort Zimmerman et al 2010
Health-related quality of life outcome measures Pooled data
Tables 2 and 3 summarize the HRQL outcomes for the three studies. All three studies reported SRS scores demonstrating significant improvement at 2 year follow-up; however, there were inconsistencies regarding the version of the SRS tool. Bridwell et al. [26] used the SRS-22 subscore, with the operative group significantly improving from baseline and having a significantly higher score at follow-up compared to the nonoperative group. Rose et al. [22] used multiple SRS versions (SRS-24, SRS-29, and SRS-30) and converted them to percentages for comparison, with both the pedicle and hook/hybrid interventions demonstrating a significant improvement at follow-up. While Zimmerman et al. [30] reported SRS-22 component scores with significant improvement in all five domains. SRS data was reported for 188 surgical intervention patients with Cohen’s d (pooled) = 1.35 95 % CI (0.93, 1.76) (Fig. 2), suggestive of a large positive effect of surgical intervention on at least 2 year follow-up SRS scores, based on Cohen’s proposed interpretation of d = 0.80 representing a large effect size [31]. Bridwell et al. [26] and Zimmerman et al. [30] also reported significant changes in ODI results. Bridwell et al. [26] reported the operative group had significantly lower ODI scores compared to the nonoperative group at 2 year follow-up. Zimmerman et al. [30] results also demonstrated significant improvement in ODI from base line to follow-up. 120 surgically treated scoliosis patients had ODI data reported with a pooled Cohen’s d = 0.88 95 % CI (0.36, 1.41) (Fig. 3); however, the broad CI suggests cautious interpretation of the potentially large positive effect of surgery on ODI scores at a minimum 2 year follow-up. One study also showed a positive effect of surgical intervention on the NRS for back and leg pain, reporting on three HRQL outcomes, ODI, SRS, and NRS [26]. Zimmerman et al. [30] also reported three HRQL outcome measures with significant results from baseline to follow-up: ODI, Short Form 36 (SF-36), and SRS-22, while Rose et al. [22] only reported SRS scores.
0
1
2
3
Effect size and 95% CI for SRS-22r Improvement Fig. 2 Forest plot of pre–post surgery Cohen’s d effect size for SRS22r improvement, pooled data n = 188
Bridwell et al 2009
Zimmerman et al 2010
Pooled data
0
0.5
1
1.5
Effect size and 95% CI for ODI Improvement Fig. 3 Forest plot of pre–post surgery Cohen’s d effect size for ODI improvement, pooled data n = 120
Radiographic changes and complications Radiographic changes were reported by all three studies; however, none of the studies examined a correlation between radiographic changes and HRQL measures. All three studies showed significant improvement in the major curve with surgical intervention [22, 26, 30]. Two studies [26, 30] reported the number of complications while one study [22] reported revision rate. Both studies reporting on number of complications categorized
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the complications as major or minor [26, 30]. One study evaluated the effects of major, minor, and no complications on the SRS subscore, finding no significant difference in the change in scores from baseline to follow-up for the three groups [26]. Zimmerman et al. [30] showed no significant differences at follow-up for ODI, SRS-22, SF-36 mental health, or SF-36 physical health questionnaires between those with or without complications. Rose et al. [22] discussed revision rate in relation to surgical technique, not HRQL measures.
Discussion Following a systematic literature review, three studies meeting inclusion criteria were identified to evaluate whether surgical intervention for treatment of adult scoliosis significantly improves quality of life as measured by patient reported HRQL outcome measures after a minimum of 2 years follow-up. Results were consistently supportive of surgical intervention for the treatment of adult scoliosis regarding improvement in quality of life as reported by participants. Recognizing that the relief of pain, restoration of function, halt of curve progression, preservation of neurologic function, and improvement in patient quality of life are the main goals in scoliosis surgery treatment [8, 32], there has been a recent shift to the use of patient-reported quality of life outcome measures to report quality of care and patient progress [32]. In this review, all HRQL outcome measures (ODI, SRS, NRS, SF-36) compared at baseline and a minimum 2 years following a surgical intervention across the three studies showed significant improvement (Tables 2, 3) [22, 26, 30]. The consistency in findings across the three studies with similar populations, despite differing surgical interventions, lack of reported effect size, and fair to good quality evidence, suggests that surgery for the treatment of adult scoliosis has a positive impact on HRQL at a minimum of 2 years post-surgery. Based on review of patient reported HRQL outcome measures and the consistency of use by articles represented in this review the SRS and ODI appear as the most appropriate HRQL outcome measures for the surgically treated adult scoliosis patient. The SRS is a disease-specific HRQL tool, recommended by a recent review as the preferred outcome measures for evaluating adult scoliosis surgery [33]. The SRS-22 covers five domains: function/ activity, pain, self-perceived image, and mental health all with five items and satisfaction with treatment with two items [34]. Scoring of items ranges from 1 (worst) to 5 (best); the total of the first four domains can be considered as a subscore with raw scores ranging from 20 (worst) to 100 (best), when including satisfaction with treatment the
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maximum raw score is 110 [34]. The validity and reliability of the SRS-22 in the adult population has been established [35, 36], the SRS-22 has been shown to be more responsive to change than the ODI in adult scoliosis patients [37], minimally important difference for both the subscores and total score have been suggested [34], and age-matched norms established [38]. However, going forward there is a need for consistent reporting in regards to SRS version used and use of the subscore, domain scores, or total score. The ODI is a back pain-specific outcome measure and is a valid and reliable tool and a primary outcome measure in spinal disorders [32]. The ODI consists of ten sections representing activities of daily living scored from 0 (no disability) to 5 (greatest disability) [39, 40]. Converted to a percentage, total scores range from 0 (no disability) to 100 (greatest disability) [39]. The SF-36 is a generic health questionnaire with thirty-six questions covering components of physical and mental health [41]. Scores in the eight different domains of the SF-36 range from 0 to 100 and are scored on norm-based scales with scores above and below 50 representing above and below average, respectively [42]. The NRS, as used in Bridwell et al. [26], is a ten point numeric scale ranging from 1 (no pain) to 10 (worst pain) [43]. Results of this review regarding the ODI and SRS outcome measures demonstrate significant post-operative improvement at a minimum of 2 year follow-up and are consistent with previous reviews [13, 14]. Bridwell et al. [26] reported a mean difference in SRS-22 subscore at follow-up between the surgical and nonoperative group of 0.7, above the minimal important difference of 0.6 [34]. Additionally, the mean changes demonstrated by Zimmerman et al. [30] between baseline and follow-up for all of the SRS-22 domains, except function, and ODI exceeded the minimally important difference [34, 44]. Additionally, this review looked at the effect size of surgical intervention on SRS and ODI HRQL outcomes for adults with scoliosis at a minimum of a 2 year follow-up, finding a large positive effect on both HRQL outcomes (Figs. 2, 3). This lends further important contextualization regarding how much difference and the relationship between surgical intervention for adult scoliosis and the improvements in SRS and ODI scores [45]. However, the interpretation of this data should be approached with caution. The study design and quality of the initial studies (fair to good) and relatively small sample sizes (n = 34–85) must be considered. None of the included articles [22, 26, 30] or the two prior reviews [13, 14] included effect size so there is limited contextual interpretation. However, taken in conjunction with the significant improvement for SRS and ODI found in all three studies [22, 26, 30] and in the reviews by Yadla et al. [13] and Liang et al. [14] the effect
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size suggests surgery has a large and positive effect on SRS-22 and ODI in the adult scoliosis population at follow-up C2 years. In regard to complications, Bridwell et al. [26] reported significant improvement in SRS-22 subscore from baseline to 2 year follow-up in patients with major complications, minor complications, and no complications. No significant difference in SRS outcomes were found at 2 year follow-up between patients treated with hook/hybrid or pedicle screw despite the hook/hybrid group having a significantly higher revision rate (9/58 compared to 1/34, P = 0.04) [22]. Despite a complication rate of 49 % (17/35 patients) Zimmerman et al. [30] still reported significant improvement in all SRS-22 components at initial follow-up and final follow-up. While Liang et al. [14] reported a complication rate of 49 % and Yadla et al. [13] noted a range from 0 to 53 % complication rate in the articles reviewed, both reviews noted an improvement in quality of life postoperatively, consistent with finds from this review. The three studies included in this review did not investigate the relationship between radiological and HRQL outcomes. Previous research has suggested the importance of restoring sagittal balance for improving HRQL [46]. However, when taking into consideration radiological outcomes together with a broad range of biopsychosocial factors, a recently published study highlighted that differences in individual outcomes might relate to factors such as depression/anxiety, body mass index, pain severity, and smoking rather than operative parameters, complications, severity of deformity, or comorbidities [27]. This suggests further research of a higher quality is still needed to establish relationships between complications, personal factors, radiographic factors, surgical intervention, and quality of life outcome measures to inform clinical decision making. This review is subject to at least three limitations. First, very few articles met the inclusion criteria, resulting in a small number of articles to review. Second, the Washington University Medical Center, where research was conducted for the Rose et al. [22] study, is one of the 15 centers contributing to the Adult Deformity Outcomes section of the Spinal Deformity Study Group dataset used by Bridwell et al. [26]. Consultation with the corresponding authors suggested minimal overlap and that the datasets were different enough to warrant inclusion of both studies in this review, though an exact participant overlap could not be determined. Third, some comparisons and conclusions were limited by the different interventions of each study. However, the inclusion criteria focused the review on quality of life outcome measures and extended the literature by examining follow-up periods of at least 2 years and reporting effect size. While the overall quality of evidence was fair to good and the sample sizes small, the consistency
in findings regarding improvement in SRS scores and ODI scores across all studies, including where high percentages of complications were noted, lends credibility to the findings, especially in concert with previous reviews.
Conclusion In answer to our research question, the results of this review support surgery as an effective treatment to improve HRQL at minimum 2 year follow-up in adults with scoliosis despite high complication rates. These findings were demonstrated in a limited number of studies with a minimum of 2 years of follow-up and fair to good quality evidence which need to be considered when interpreting the results. Additional high quality studies are needed to confirm these findings and to determine if and to what extent there is interaction between variables resulting in complications and worse outcomes from surgery for some individuals compared to others in the adult scoliosis population. Future efforts to synthesize the literature in this field would benefit from increased consistency of measurement instruments, including using the same versions, larger sample sizes, longer follow-ups, and more rigorous study designs with reports of statistical power and clinically meaningful effect sizes. Acknowledgments We gratefully acknowledge Brenda Sides from the research team of Lawrence G. Lenke, M.D., Washington University School of Medicine, for providing the SRS data from the Rose et al. [22] study. We would also like to acknowledge an anonymous reviewer for helpful comments during manuscript preparation. This study was financially supported by funds from the regional agreement on medical training and clinical research (ALF) between Stockholm County Council and Karolinska Institutet, Karolinska Institutet research funds, and the Swedish Research Council (Projects K201399X-22268-01-3 and K2013-52X-22198-01-3). Conflict of interest
None.
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REVIEW ARTICLE
Quality of life outcomes in surgically treated adult scoliosis patients: a systematic review Jennifer Theis • Paul Gerdhem • Allan Abbott
Received: 5 March 2014 / Revised: 20 September 2014 / Accepted: 21 September 2014 Ó Springer-Verlag Berlin Heidelberg 2014
Abstract Purpose The aim of this systematic review was to identify prospective studies reporting the impact of surgical intervention on health-related quality of life (HRQL) outcomes for adults with scoliosis at a minimum 2 year follow-up. Method An electronic database search was conducted for January 2000–November 2013 in conjunction with a reference list search of two related systematic reviews for prospective studies of adults with scoliosis reporting HRQL outcome measure. Methodological quality of included articles was assessed using the Downs and Black checklist. Cohen’s d effect size was calculated for Scoliosis Research Society Questionnaire (SRS) and Oswestry Disability Index (ODI) outcomes for included studies and pooled data.
J. Theis (&) A. Abbott Department of Clinical and Rehabilitation Services, Faculty of Health Science and Medicine, Bond Institute of Health and Sport, Bond University, 2 Promethean Way, Robina, QLD 4226, Australia e-mail: [email protected] P. Gerdhem Department of Orthopaedics, Department of Clinical Science, Intervention and Technology (CLINTEC), Karolinska Institutet, Karolinska University Hospital, 141 86 Stockholm, Sweden A. Abbott Department of Physical Therapy, Karolinska University Hospital, 141 86 Stockholm, Sweden A. Abbott Division of Physiotherapy, Department of Neurobiology, Care Sciences and Society, Karolinska Institutet, 141 86 Stockholm, Sweden
Results The database and reference list searches returned 349 potential articles; three articles met the inclusion criteria. Downs and Black scores ranged from 18/28 to 21/28 (fair–good quality evidence). Total number of 188 patients were treated surgically and had a mean age of 38 years or older. All studies showed significant improvement in reported HRQL outcomes for at least a 2 year follow-up. The Cohen’s d effect size for SRS was d = 1.4 (n = 188, 95 % CI; 0.9, 1.8) and for ODI d = 0.9 (n = 120, 95 % CI; 0.4, 1.4). Conclusion Findings from this review suggest surgery improves HRQL in patients with adult scoliosis at a minimum 2 year follow-up. However, these findings are based on limited data of fair to good quality which needs to be taken into consideration when interpreting the results and highlights the need for additional high quality prospective studies. Keywords Adult Scoliosis Surgery Quality of life Scoliosis Research Society Oswestry Disability Index
Introduction While scoliosis is often associated with childhood and adolescence, increased life expectancy and demographic shifts suggest increasing need for investigations focused on adult scoliosis [1, 2]. Reported prevalence rates of adult scoliosis vary widely in the literature from 9 % [3] to 68 % [1], with increased prevalence associated with older age [3]. Adult scoliosis, a spinal deformity defined as a coronal plane Cobb angle [10° [4] in the skeletally mature patient [2, 5], has two primary pathogeneses; idiopathic scoliosis and degenerative scoliosis [2, 5, 6]. Adult idiopathic scoliosis is associated with a progression or secondary spinal
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degeneration stemming from childhood or adolescent idiopathic scoliosis while adult degenerative scoliosis develops without a prior history of scoliosis, often from degenerative changes to intervertebral discs and facet joints adversely affecting a motion segment [2, 5–7]. Both types lead to asymmetric degeneration, loading, and deformity of the spine interacting in an often progressive cycle [2, 5, 6]. The degenerative and progressive nature of adult scoliosis often results in spinal segment instability, spondyloarthritis, spondylosis, and spinal stenosis [2, 5–7]. Clinically, adult scoliosis manifests as back pain, radicular pain, claudication symptoms, and curve progression, with indications for treatment stemming from disability and pain [2, 6–8]. Considering the associated disability and pain, treatment goals should include improving quality of life and decreasing pain [8]. While nonsurgical intervention is a first treatment option, a systematic review of this approach found insufficient evidence to support nonoperative management of adult scoliosis [9], and a further study found no significant improvement in Oswestry Disability Index (ODI), numeric rating scale (NRS), or Scoliosis Research Society Questionnaire-22 (SRS-22) measures for patients with scoliosis-related back pain treated with nonoperative intervention at 2 year follow-up [10]. However, surgery in the adult scoliosis patient is complicated by their more ridged curves, co-morbidities, and increased spinal degenerative changes requiring more extensive surgical intervention compared to adolescent idiopathic scoliosis [6] and has been associated with higher complication rates (13.4 % in adults [11] compared with 5.7 % in adolescents [12]) based on review of the Scoliosis Research Society morbidity and mortality database. Despite this, two recent systematic reviews suggest operative interventions for adult scoliosis yield significant improvement in clinical outcomes and radiographic improvements along with the need to consider the high rate of complications [13, 14]. Yadla et al. [13] evaluated articles related to adult scoliosis or adult spinal deformity, possibly including other causes in addition to scoliosis. Additionally, by including studies with participant mean age of [18 years at time of surgery they reviewed studies incorporating adult and adolescent scoliosis [13]. Liang et al. [14] and Yadla et al. [13] included prospective and retrospective studies rated as low to moderate quality evidence and included studies that did not report health-related quality of life (HRQL) data. The aim of this review is to determine, through systematic evaluation of prospective research studies, if surgical intervention for a primary diagnosis of adult scoliosis has a significant improvement on HRQL outcome measures at a minimum 2 year follow-up; radiographic changes and complication rate will also be evaluated.
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Methods Literature review A search of seven electronic databases, PubMed, CINAHL, EMBASE, Web of Knowledge, PEDro, The Cochrane Library, and PsycINFO, was conducted in November 2013 to locate potential articles using search terms and filters relevant to each database along with a reference list search of two recent systematic reviews [13, 14] (retrieved through a PubMed search). The databases, search terms, filters, and results of the search are outlined in Table 1. Inclusion criteria were: (1) primary diagnosis of adult scoliosis, (2) age C18 years old at time of surgery, (3) HRQL outcome measure reported at baseline and final follow-up, (4) follow-up C2 years, (5) prospective study (randomized control trial, clinical trial, quasi-randomized trial), and (6) full text available in English. Exclusion criteria were: studies of spinal deformity primarily attributed to a condition other than scoliosis (e.g., kyphosis, spondylolisthesis, or spinal stenosis) or scoliosis resulting from a neuromuscular condition, osteopenia, traumatic injury, or not specified. Critical appraisal The Downs and Black checklist, 27 item checklist to evaluate the methodological quality of randomized and nonrandomized studies with health care interventions [15], was used to evaluate the included studies. The checklist provides assessment parameters for five main areas, including study reporting, external validity, internal validity, bias and confounding, and statistical power [15] and has been evaluated as a suitable quality assessment tools for use in systematic reviews [16, 17]. For the external validity subscales, the general population was considered to be that of the hospital/specialist treating adults with spinal deformity; thus, the participants in these studies are representative of that population. The tool was modified for use in this review, as in previous reviews, regarding scoring the question concerning statistical power to 1 if a power or sample size calculation was present and 0 if no power or sample size calculation was present [18–21]. The Downs and Black scores are divided into four quality categories: excellent (26–28), good (20–25), fair (15–19), and poor (B14); only a randomized control trial can obtain the top score of 28 [20, 21]. All studies were independently rated by two reviewers (JT and AA) with complete agreement between raters. Statistical analysis Statistical calculations were done using Microsoft Excel (Excel 2010, Microsoft). Prior to statistical analysis, SRS
20
3 3 6
2 10 12 88
2 5 7 85
2 3 5 86
11 11 84
0
Total number satisfying assessment criteria
scores reported with different SRS (SRS-24, SRS-29, and SRS-30) instruments were converted to SRS-22r scores. The raw data containing individual responses to questions on the SRS-24/29/30 was obtained from Rose et al. [22]. For raw data reported using the SRS-24, the conversion algorithm (SRS-22r = 0.956 ? 0.782 9 SRS-24) [23] was applied. The raw data that was in SRS-29 and SRS-30 formats was recalculated directly to SRS-22r scores. Cohen’s d effect sizes was calculated for pre–post data using the pre- and post-mean scores and standard deviations using an online calculator [24]. Microsoft Excel meta-analysis algorithms using a random effects model [25] were used to map out individual study effect size and 95 % confidence interval (CI) data as well as pooled data for the included studies for SRS-22 and ODI.
Literature review Electronic database and secondary reference list searches yielded 349 potential articles. After abstract and title review and removal of duplicates, 20 articles were retrieved in full text (Fig. 1). After full text review, 6 articles met the inclusion criteria; however, four articles [26–29] had population duplication through the use of the Adult Deformity Outcome section of the Spinal Deformity Study Group database with similar recruitment time periods or insufficient information to determine extent of participant overlap. Full text of these articles was further reviewed and the one best matching the inclusion criteria was kept, resulting in 3 articles for inclusion in this review (Fig. 1). One study compared surgical treatment to nonoperative interventions [26], one study compared two different surgical procedures [22], and one study compared baseline to 2 year follow-up of a relatively homogenous cohort [30]. Critical appraisal
Total number of articles retrieved for full text
PEDro, The Cochrane Library, and PsycINFO (search 09.11.2013) with same search strategy—no additional articles17
2000–2013 english article Quality of life AND outcome AND surgery AND adult AND (scoliosis OR spine deformity) 4. Web of knowledge 09.11.2013
5. Secondary reference list search of systematic reviews [13, 14]
2001–2013 human article Quality of life AND outcome AND surgery AND adult AND (scoliosis or spine deformity) 3. EMBASE 09.11.2013
107
2000–2013 english human peer reviewed Quality of life AND outcome AND surgery AND adult AND (scoliosis or spine deformity) 2. CINAHL 09.11.2013
143
2000–2013 english humans Quality of life AND outcome AND surgery AND adult AND (scoliosis or spine deformity) 1. PubMed 09.11.2013
147
Filters used Search terms
110
Results
Database and date of search
Table 1 Details of literature search: databases used, search terms, and inclusion filters
Number prior to applying filters
Number after application of filters
Duplicated
Number of new articles not included in previous searches
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Table 2 summarizes the patient population, study design, findings, and critical appraisal, including Downs and Black scores for the three articles. Two articles were of fair quality of evidence, with scores of 19/28 [26] and 18/28 [22]; the third study was of good quality of evidence scoring 21/28 [30]. All of the studies were prospective cohort studies involving surgical intervention, thus precluding blinding and randomizing of the participants and concealment from the staff. This resulted in low scores for the internal validity bias subscales of the Downs and
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Literature Search of Databases
PubMed 84
CINAHL 86
Reference list search 6
EMBASE 85
Web of Knowledge 88
Potentially relevant articles 349
Exclusions Articles excluded based on title/abstract and duplication 329
Articles retrieved in full text 20
Articles not meeting inclusion criteria 14 Articles meeting inclusion criteria 6
Articles excluded for study population duplication 3 Articles included for review 3 Fig. 1 Flowchart of the literature review process
Black. Additionally, none of the authors discussed power or if their studies indicated a clinically meaningful effect. Not assessed on the Downs and Black, but of note as a potential source of bias, Bridwell et al. [26] disclosed that the multicenter Spinal Deformity Study Group database receives industry funding.
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Participants and interventions The number of participants ranged from 35 [30] to 160 (85 treated operatively) [26] with mean age of 38 years or older. Females were more frequent than males [22, 30]; however, sex distribution was not reported in one of the
Consecutively enrolled between 2002–2005 n = 75 treated nonoperatively
Adult symptomatic lumbar scoliosis
Double major scoliosis, thoracolumbar and lumbar curves, lumbar curve had to be as large as thoracic curve
n = 85 treated operatively
Primary case, no prior surgical intervention
Distally fused to sacrum or lumbar
Proximally fused to upper thoracic
Other without medication.
Age range 40–80 years
Medication plus (physiotherapy and/or injections)
Medication
Observation
Prospective cohort study
n = 160
Bridwell et al. [26]
Study design and intervention
Patient population
References
Numerical Rating Scale back pain and leg pain scores (NRS, 0–10)
Oswestry Disability Index
Secondary
2 year
1 year
2 months
Operative
Downs and Black Score = 19, fair quality of evidence
Significant improvement
Significantly better in operative than nonoperative
NRS Back and Leg
Significantly better in operative than nonoperative
ODI
Insignificant difference between minor and major complication groups
No discussion of power
45 % of nonoperative group lost at follow-up
Age (40-59 years old and 60-80 old): no significant difference between age groups Minor and major surgical complications:
Nonoperative treatment compliance not reported
Operative: significant improvement
Nonoperative: no significant change
6 months 1 year 2 year
No information on patient sex
SRS QOL subscores
Nonoperative
Critical appraisal and Downs and Black score Representativeness not reported
Result
Only 2 year follow-up results reported
Pre-treatment baseline
Scoliosis Research Society Quality of Life subscore (SRS QOL)
Measurement intervals
Primary
Outcome measures
Table 2 Summary and critical appraisal of included articles in this review
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123 Thoracic kyphosis: significant decrease in pedicle screw group compared to hook/hybrid
Sagittal plane correction
Primary case, no prior surgical intervention
31 females, 3 males
Mean age 38.1 ± 12 years
29 females, 5 males
Mean age 38.3 ± 13 years
Significant improvement for both cohorts
SRS scores
2 year follow-up
Revision rate: significantly more in hook/hybrid than pedicle screw
Estimated blood loss: no significant difference Operative time: significantly more in hook/hybrid group than pedicle screw group
Operative parameters or revision rate
SRS scores at 2 year follow-up
Coronal plane correction Significantly more in pedicle screw cohort than hook/hybrid cohort
Final follow-up
Result
Hook/hybrid consructs:
Scoliosis Research Society (SRS) scores, varying versions (SRS-24, SRS-29, SRS-30) converted to percentages
Minimum 2 year follow-up (mean 36 months, range 2–6 years)
Pre-operative baseline
Measurement intervals
Lumbar lordosis and sagittal balance: no significant change between groups
Average levels fused = 10.1
n = 34 Hook/ hybrid constructs
Operative parameters or revision rate
Radiographic measures of coronal and sagittal plane
Outcome measures
Pedicle screw instrumentation:
Single thoracic, double thoracic, double major, thoracolumbar, lumbar curves
n = 34 Pedicle screw instrumentation
Idiopathic scoliosis
Average levels fused = 9.7
Prospective matched cohort study
n = 68
Rose et al. [22]
Study design and intervention
Patient population
References
Table 2 continued
Downs and Black Score = 18, fair quality of evidence
No discussion of power
Recruitment timeframe not indicated
Follow-up range not reported
Inconsistent reporting of actual probability values
Patient characteristics lost to follow-up not reported
Critical appraisal and Downs and Black score
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Improvement remained significant at final follow-up
Significant improved at initial follow-up Peaking at 2 year follow-up
SRS-22
Significant improvements at initial follow-up
ODI and SF-36
49 % (17/35 patients)
(final follow-up)
Complication rate
No prior surgical intervention, exception simple decompression procedures
Final follow-up at least 2 years (49.4 ± 17.7 months)
No significant difference between interventions
Significant for all curve types
Coronal correction (final followup)
Result
Little change from initial to final follow-up
Scoliosis Research Society 22 (SRS-22)
Short Form 36 (SF-36)
Follow-ups beginning 6 weeks post-surgery
Pre-operative baseline
Measurement intervals
33 women, 2 men
Mean age 56.3 ± 11.0 years
Number with sacral fusion = 20
Double major, thoracolumbar curves
Complication rate
Surgery between 2000–2006 Oswestry Disability Index (ODI)
Coronal correction
Outcome measures
Prospective cohort study
Mean levels fused = 10 ± 2.8
n = 35
Zimmerman et al. [30]
Study design and intervention
Scoliosis, excluding a more severe spinal abnormality (e.g. stenosis, kyphosis, etc.)
Patient population
References
Table 2 continued
Downs and Black Score = 21, good quality of evidence
No discussion of power
Patient characteristics lost to follow-up not reported
Critical appraisal and Downs and Black score
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Adult symptomatic scoliosis
Idiopathic scoliosis
Scoliosis, excluding a more severe spinal abnormality (e.g., stenosis, kyphosis, etc.)
Bridwell et al. [26]
Rose et al. [22]
Zimmerman et al. [30]
4 ± 1.5
C2
2
Followup (years)
64 ± 24/ 46 ± 16*
Not reported
34 ± 15/ 20 ± 16a
ODI (baseline/ follow-up) (mean ± SD)
SRS: 2.21 (1.72, 2.70)
Selfimage 2.1 ± 0.6/ 3.3 ± 0.7e,*
Satisfaction 1.6 ± 1.2/ 2.9 ± 0.5e,*
Activity 2.5 ± 0.36/ 3.2 ± 0.3d,* Mental health 2.0 ± 0.5/ 3.1 ± 0.2e,*
49° ± 16°/ 20° ± 9°*
ODI: 0.88 (0.56, 1.19)
Pain 2.3 ± 0.4/ 3.3 ± 0.4e,*
f
e
d
c
b
a
Revision rate
SRS-22
Significance compared to hook/hybrid group at final follow-up, of P \ 0.05
SRS-24, SRS-29, SRS-30 converted by authors to percentages for comparison
SRS-QOL subscore
Values for surgical group, significance compared to nonoperative group at 2 year follow-up, P \ 0.05
* Significance compared to baseline, P \ 0.05
56° ± 11°/ 26° ± 11°d,* 63° ± 16°/ 38° ± 18°
SRS: 0.80 (0.50, 1.10)
56° ± 15°/ 27° ± 13°a,*
Major curve (°) (baseline/followup) (mean ± SD)
SRS: 1.41 (1.01, 1.80)
69 % ± 10 %/ 79 % ± 13 %*c
71 % ± 10 %/ 80 % ± 13 %*c
ODI: 0.89 (0.69, 1.09)
3.1 ± 0.5b/ 3.8 ± 0.7*ab SRS: 1.15 (0.92, 1.38)
HRQL pre–post effect size (Cohen’s d, 95 % CI)
SRS score (baseline/followup) (mean ± SD)
ODI Oswestry Disability Index, SRS Scoliosis Research Society Quality of Life scores, HRQL health-related quality of life outcome measure
56 ± 11
38 ± 12
34 (hook/hybrid) (68) 35 (35)
38 ± 13
40–80
Age (years) (range or mean ± SD)
34 (pedicle)
85 (160)
Total number of participants in surgical cohort(s) (total number participates)
Mean ± SD included where reported by author
Diagnosis
References
Table 3 Summary of surgical outcomes from the three articles included in review
17/35
9/58f
1/34f
30/85
Number of complications/ number of cases
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studies [26]. No prior surgical intervention, except possibly a simple decompression procedure [22, 26, 30], was an inclusion criteria in each of the studies, suggesting a degree of homogeneity across all study participants. Description of surgical interventions varied across the studies rendering it difficult to make a direct comparison (Table 2). Bridwell et al. [26] reported level of fusion, Rose et al. [22] reported pedicle screw compared with hook/hybrid instrumentation, and Zimmerman et al. [30] reported on surgical intervention based on anterior, posterior, or combined approach and staging.
Bridwell et al 2009 Rose et al 2009, pedicle surgery cohort Rose et al 2009, hook/hybrid surgery cohort Zimmerman et al 2010
Health-related quality of life outcome measures Pooled data
Tables 2 and 3 summarize the HRQL outcomes for the three studies. All three studies reported SRS scores demonstrating significant improvement at 2 year follow-up; however, there were inconsistencies regarding the version of the SRS tool. Bridwell et al. [26] used the SRS-22 subscore, with the operative group significantly improving from baseline and having a significantly higher score at follow-up compared to the nonoperative group. Rose et al. [22] used multiple SRS versions (SRS-24, SRS-29, and SRS-30) and converted them to percentages for comparison, with both the pedicle and hook/hybrid interventions demonstrating a significant improvement at follow-up. While Zimmerman et al. [30] reported SRS-22 component scores with significant improvement in all five domains. SRS data was reported for 188 surgical intervention patients with Cohen’s d (pooled) = 1.35 95 % CI (0.93, 1.76) (Fig. 2), suggestive of a large positive effect of surgical intervention on at least 2 year follow-up SRS scores, based on Cohen’s proposed interpretation of d = 0.80 representing a large effect size [31]. Bridwell et al. [26] and Zimmerman et al. [30] also reported significant changes in ODI results. Bridwell et al. [26] reported the operative group had significantly lower ODI scores compared to the nonoperative group at 2 year follow-up. Zimmerman et al. [30] results also demonstrated significant improvement in ODI from base line to follow-up. 120 surgically treated scoliosis patients had ODI data reported with a pooled Cohen’s d = 0.88 95 % CI (0.36, 1.41) (Fig. 3); however, the broad CI suggests cautious interpretation of the potentially large positive effect of surgery on ODI scores at a minimum 2 year follow-up. One study also showed a positive effect of surgical intervention on the NRS for back and leg pain, reporting on three HRQL outcomes, ODI, SRS, and NRS [26]. Zimmerman et al. [30] also reported three HRQL outcome measures with significant results from baseline to follow-up: ODI, Short Form 36 (SF-36), and SRS-22, while Rose et al. [22] only reported SRS scores.
0
1
2
3
Effect size and 95% CI for SRS-22r Improvement Fig. 2 Forest plot of pre–post surgery Cohen’s d effect size for SRS22r improvement, pooled data n = 188
Bridwell et al 2009
Zimmerman et al 2010
Pooled data
0
0.5
1
1.5
Effect size and 95% CI for ODI Improvement Fig. 3 Forest plot of pre–post surgery Cohen’s d effect size for ODI improvement, pooled data n = 120
Radiographic changes and complications Radiographic changes were reported by all three studies; however, none of the studies examined a correlation between radiographic changes and HRQL measures. All three studies showed significant improvement in the major curve with surgical intervention [22, 26, 30]. Two studies [26, 30] reported the number of complications while one study [22] reported revision rate. Both studies reporting on number of complications categorized
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the complications as major or minor [26, 30]. One study evaluated the effects of major, minor, and no complications on the SRS subscore, finding no significant difference in the change in scores from baseline to follow-up for the three groups [26]. Zimmerman et al. [30] showed no significant differences at follow-up for ODI, SRS-22, SF-36 mental health, or SF-36 physical health questionnaires between those with or without complications. Rose et al. [22] discussed revision rate in relation to surgical technique, not HRQL measures.
Discussion Following a systematic literature review, three studies meeting inclusion criteria were identified to evaluate whether surgical intervention for treatment of adult scoliosis significantly improves quality of life as measured by patient reported HRQL outcome measures after a minimum of 2 years follow-up. Results were consistently supportive of surgical intervention for the treatment of adult scoliosis regarding improvement in quality of life as reported by participants. Recognizing that the relief of pain, restoration of function, halt of curve progression, preservation of neurologic function, and improvement in patient quality of life are the main goals in scoliosis surgery treatment [8, 32], there has been a recent shift to the use of patient-reported quality of life outcome measures to report quality of care and patient progress [32]. In this review, all HRQL outcome measures (ODI, SRS, NRS, SF-36) compared at baseline and a minimum 2 years following a surgical intervention across the three studies showed significant improvement (Tables 2, 3) [22, 26, 30]. The consistency in findings across the three studies with similar populations, despite differing surgical interventions, lack of reported effect size, and fair to good quality evidence, suggests that surgery for the treatment of adult scoliosis has a positive impact on HRQL at a minimum of 2 years post-surgery. Based on review of patient reported HRQL outcome measures and the consistency of use by articles represented in this review the SRS and ODI appear as the most appropriate HRQL outcome measures for the surgically treated adult scoliosis patient. The SRS is a disease-specific HRQL tool, recommended by a recent review as the preferred outcome measures for evaluating adult scoliosis surgery [33]. The SRS-22 covers five domains: function/ activity, pain, self-perceived image, and mental health all with five items and satisfaction with treatment with two items [34]. Scoring of items ranges from 1 (worst) to 5 (best); the total of the first four domains can be considered as a subscore with raw scores ranging from 20 (worst) to 100 (best), when including satisfaction with treatment the
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maximum raw score is 110 [34]. The validity and reliability of the SRS-22 in the adult population has been established [35, 36], the SRS-22 has been shown to be more responsive to change than the ODI in adult scoliosis patients [37], minimally important difference for both the subscores and total score have been suggested [34], and age-matched norms established [38]. However, going forward there is a need for consistent reporting in regards to SRS version used and use of the subscore, domain scores, or total score. The ODI is a back pain-specific outcome measure and is a valid and reliable tool and a primary outcome measure in spinal disorders [32]. The ODI consists of ten sections representing activities of daily living scored from 0 (no disability) to 5 (greatest disability) [39, 40]. Converted to a percentage, total scores range from 0 (no disability) to 100 (greatest disability) [39]. The SF-36 is a generic health questionnaire with thirty-six questions covering components of physical and mental health [41]. Scores in the eight different domains of the SF-36 range from 0 to 100 and are scored on norm-based scales with scores above and below 50 representing above and below average, respectively [42]. The NRS, as used in Bridwell et al. [26], is a ten point numeric scale ranging from 1 (no pain) to 10 (worst pain) [43]. Results of this review regarding the ODI and SRS outcome measures demonstrate significant post-operative improvement at a minimum of 2 year follow-up and are consistent with previous reviews [13, 14]. Bridwell et al. [26] reported a mean difference in SRS-22 subscore at follow-up between the surgical and nonoperative group of 0.7, above the minimal important difference of 0.6 [34]. Additionally, the mean changes demonstrated by Zimmerman et al. [30] between baseline and follow-up for all of the SRS-22 domains, except function, and ODI exceeded the minimally important difference [34, 44]. Additionally, this review looked at the effect size of surgical intervention on SRS and ODI HRQL outcomes for adults with scoliosis at a minimum of a 2 year follow-up, finding a large positive effect on both HRQL outcomes (Figs. 2, 3). This lends further important contextualization regarding how much difference and the relationship between surgical intervention for adult scoliosis and the improvements in SRS and ODI scores [45]. However, the interpretation of this data should be approached with caution. The study design and quality of the initial studies (fair to good) and relatively small sample sizes (n = 34–85) must be considered. None of the included articles [22, 26, 30] or the two prior reviews [13, 14] included effect size so there is limited contextual interpretation. However, taken in conjunction with the significant improvement for SRS and ODI found in all three studies [22, 26, 30] and in the reviews by Yadla et al. [13] and Liang et al. [14] the effect
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size suggests surgery has a large and positive effect on SRS-22 and ODI in the adult scoliosis population at follow-up C2 years. In regard to complications, Bridwell et al. [26] reported significant improvement in SRS-22 subscore from baseline to 2 year follow-up in patients with major complications, minor complications, and no complications. No significant difference in SRS outcomes were found at 2 year follow-up between patients treated with hook/hybrid or pedicle screw despite the hook/hybrid group having a significantly higher revision rate (9/58 compared to 1/34, P = 0.04) [22]. Despite a complication rate of 49 % (17/35 patients) Zimmerman et al. [30] still reported significant improvement in all SRS-22 components at initial follow-up and final follow-up. While Liang et al. [14] reported a complication rate of 49 % and Yadla et al. [13] noted a range from 0 to 53 % complication rate in the articles reviewed, both reviews noted an improvement in quality of life postoperatively, consistent with finds from this review. The three studies included in this review did not investigate the relationship between radiological and HRQL outcomes. Previous research has suggested the importance of restoring sagittal balance for improving HRQL [46]. However, when taking into consideration radiological outcomes together with a broad range of biopsychosocial factors, a recently published study highlighted that differences in individual outcomes might relate to factors such as depression/anxiety, body mass index, pain severity, and smoking rather than operative parameters, complications, severity of deformity, or comorbidities [27]. This suggests further research of a higher quality is still needed to establish relationships between complications, personal factors, radiographic factors, surgical intervention, and quality of life outcome measures to inform clinical decision making. This review is subject to at least three limitations. First, very few articles met the inclusion criteria, resulting in a small number of articles to review. Second, the Washington University Medical Center, where research was conducted for the Rose et al. [22] study, is one of the 15 centers contributing to the Adult Deformity Outcomes section of the Spinal Deformity Study Group dataset used by Bridwell et al. [26]. Consultation with the corresponding authors suggested minimal overlap and that the datasets were different enough to warrant inclusion of both studies in this review, though an exact participant overlap could not be determined. Third, some comparisons and conclusions were limited by the different interventions of each study. However, the inclusion criteria focused the review on quality of life outcome measures and extended the literature by examining follow-up periods of at least 2 years and reporting effect size. While the overall quality of evidence was fair to good and the sample sizes small, the consistency
in findings regarding improvement in SRS scores and ODI scores across all studies, including where high percentages of complications were noted, lends credibility to the findings, especially in concert with previous reviews.
Conclusion In answer to our research question, the results of this review support surgery as an effective treatment to improve HRQL at minimum 2 year follow-up in adults with scoliosis despite high complication rates. These findings were demonstrated in a limited number of studies with a minimum of 2 years of follow-up and fair to good quality evidence which need to be considered when interpreting the results. Additional high quality studies are needed to confirm these findings and to determine if and to what extent there is interaction between variables resulting in complications and worse outcomes from surgery for some individuals compared to others in the adult scoliosis population. Future efforts to synthesize the literature in this field would benefit from increased consistency of measurement instruments, including using the same versions, larger sample sizes, longer follow-ups, and more rigorous study designs with reports of statistical power and clinically meaningful effect sizes. Acknowledgments We gratefully acknowledge Brenda Sides from the research team of Lawrence G. Lenke, M.D., Washington University School of Medicine, for providing the SRS data from the Rose et al. [22] study. We would also like to acknowledge an anonymous reviewer for helpful comments during manuscript preparation. This study was financially supported by funds from the regional agreement on medical training and clinical research (ALF) between Stockholm County Council and Karolinska Institutet, Karolinska Institutet research funds, and the Swedish Research Council (Projects K201399X-22268-01-3 and K2013-52X-22198-01-3). Conflict of interest
None.
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