Best Treatment for Adolescent Idiopathic Scoliosis: What Do Current Systematic Reviews Tell Us?

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Chapter 33 Best Treatment for Adolescent Idiopathic Scoliosis: What Do Current Systematic Reviews Tell Us?

LORI A. DOLAN, PhD, STUART L. WEINSTEIN, MD

Adolescent idiopathic scoliosis (AIS) is a structural, lateral, rotated curvature of the spine of at least 10 degrees (using the Cobb measurement method) arising in otherwise normal children at or around puberty. The diagnosis is one of exclusion, made only when other causes of scoliosis, such as vertebral malformation, neuromuscular disorder, and syndromic conditions have been ruled out. Curvatures less than 10 degrees are viewed as a variation of normal because they have little potential for progression.

When defined as at least a 10-degree angle, epidemiologic studies estimate that 1% to 3% of the at-risk population (children aged 10–16 years) will have some degree of curvature, with most curves requiring no intervention.1,2

Treatment of any condition is an attempt to alleviate current problematic signs and symptoms, and to ultimately alter long-term natural history. Most patients with AIS do not initially seek treatment because of symptoms, but rather because of the finding of trunk asymmetry noted during screening or incidentally during well-child examinations. Most subjects have no complaints and will continue to do well throughout their lives. Therefore, the treatment of AIS during adolescence is mainly an attempt to prevent future problems.

Despite the fact that idiopathic scoliosis has been studied and treated for many centuries, the lack of knowledge concerning the etiopathogenesis of the condition has limited clinicians’ ability to prevent the disease. They are therefore left to interventions aimed at secondary prevention, where the goal is to avoid the negative side effects of the established disease. And although operative interventions have become safer and more effective at restoring normal anatomy since the 1950s, one could argue that few, if any, advances have been made in nonoperative treatment. Roach3 reports that as early as 400 BC, Hippocrates recognized the condition and used a system of intermittently applied forces to apply distraction and lateral pressure to reduce the deformity (Fig. 33-1, A). The Milwaukee brace and, more recently, thoracolumbosacral orthosis (TLSO) use these same principles to effect curve reduction (see Figs. 33-1, B and C). This lack of advancement would be acceptable if clinicians were certain that the interventions actually demonstrated the ability to achieve anatomic and quality-of-life goals of the patient. However, this is not necessarily the case. Curves continue to progress to the point where only surgery can correct the deformity, and prevent future progression and possible pulmonary compromise; patients continue to report dissatisfaction with daily bracing and exercise regimens, and as adults, many face back pain, alterations in body image, and pulmonary impairment. Therefore, in light of these shortcomings, it is imperative that clinicians and patients have access to evidence concerning the effectiveness and side effects of these treatments, so they can knowledgeably make decisions based on their own personal risk/benefit ratios. Systematic reviews, the explicit combination of findings from multiple studies, can provide the reliable and accurate conclusions about effectiveness that patients should receive to make informed decisions. This chapter summarizes the existing systematic reviews of nonoperative treatments for AIS and discusses the practical implications of the findings.

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FIGURE 33-1 Orthoses to treat scoliosis. A, An early scoliosis orthosis case. B, A Milwaukee orthosis case. C, A Rosenberger thoracolumbosacral orthosis case.

(A: From Roach JW: Adolescent idiopathic scoliosis. Nonsurgical treatment. In Weinstein SL (ed): The Pediatric Spine. New York, Raven Press, 1994, pp 498, 503, by permission; B, C: Courtesy Stuart L. Weinstein, MD.)

SUMMARY OF REVIEWS

We conducted a search of the Cochrane, Medline, DARE (Database of Abstracts of Reviews of Effects), and ACP Journal Club databases for meta-analyses and systematic reviews of AIS treatment. After excluding articles concerning operative treatments, the search yielded six studies. The major objectives of these studies included effectiveness of mass screening, exercises, bracing, observation, and electrical stimulation. All but one were quantitative reviews that attempted to combine outcome rates across studies. Table 33-1 summarizes the studies that were included in each of the reviews.

TABLE 33-1 Characteristics of Primary Studies Included in the Reviews

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Effectiveness of Nonsurgical Treatment for Idiopathic Scoliosis

The first systematic review of nonoperative treatment for AIS was conducted by an Italian group and published in 1991.4 This study was conducted to gather evidence for or against routine screening for AIS, assuming that early detection must be justified by early, effective treatment. Thus, the question: Are available nonoperative treatments effective in changing the natural history of the condition?

The authors conducted a literature search of the Medline database, searching for English-language articles published between 1975 and 1987. Keywords included “therapy,” “scoliosis,” “random allocation,” “natural history,” “prevention,” “control,” “occurrence,” “mass screening,” “child,” “adolescent,” and “follow-up studies.” The search yielded 111 articles that were reviewed by 2 of the authors. Studies were combined into natural history and therapy studies. Criteria for including natural history studies were few; they required a radiograph at the beginning and end of treatment, criteria for progression, and the number of patients who progressed. Thus, seven studies were included in the final review. The therapy studies included those with patients whose curves were less than 50 degrees at treatment initiation, and 17 articles were included in the final review. The authors calculated the percentage of patients who progressed more than 5 degrees or did not respond favorably (finished treatment with a curve greater than 45 degrees or went on to surgery) and then derived a 95% confidence interval (CI) around the proportion for the individual natural history and treatment studies. In addition, pooled rates were developed by calculating the direct standardized ratio and 95% CI.

The seven natural history studies included curves greater than 5 degrees in patients between the ages of 7 and 16, with Risser signs ranging from 0 to 5. The authors note that the studies were heterogeneous in terms of the rates and note that study design was a factor: The percentage of patients with progressive curves was lower in the prospective studies (7%) than in the retrospective studies (25%). Overall, the range of progression was from 5% to 56%, with a pooled proportion of 15% (95% CI, 3–27%). The 17 therapy studies included 11 studies of bracing; the rest concerned lateral electrical surface stimulation (LESS), posture training, and exercise. They found an overlap in the CIs for LESS (17.5–39.5%) and bracing (13.3–45.5%), although they note these studies were heterogenous in terms of the study end points, and that they also differed according to study design. When failure was the outcome, the failure rate of treatment among curves less than 30 degrees at initiation of bracing was lower (4%) than for those curves greater than 30 degrees (24%).

Overall, this review makes 2 conclusions. First, curves less than 30 degrees had a better prognosis, regardless of whether they were treated, than those greater than 30 degrees, indicating the usefulness of early detection and treatment. Second, unlike the case of failure, the proportion of progressive curves was not different between the treated and untreated groups. To explain this second finding, the authors postulate that 3 conditions may exist: (1) available treatments do not work; (2) treatments cannot stop progression, but they can slow it until maturity; or (3) treatments do work, but they could not demonstrate their effectiveness because of the heterogeneity of the treated and untreated groups. For the clinician, this review indicates that bracing of small-to-moderate-sized curves can decrease the risk for failure relative to observation or LESS. However, when considering curve progression itself, this systematic review draws a range of conclusions, including that treatments to prevent curve progression (bracing and LESS) do not work, and the essentially opposite conclusion that treatments do work, but the literature cannot prove their effectiveness. This review alone, therefore, could not provide evidence to make any decision in practice.

Screening for Idiopathic Scoliosis in Adolescents: U.S. Preventive Services Task Force

The U.S. Preventive Services Task Force (USPSTF) released their recommendations for screening in 19965 and updated them in 2004.6 In 1996, they stated, “There is insufficient evidence to recommend for or against routine screening of asymptomatic adolescents for idiopathic scoliosis”6 partly because of the lack of convincing evidence that nonoperative treatment of curves detected early results in better health outcomes. In 2004, the USPSTF re-examined their recommendation in light of research published between 1994 and 2002, and attempted to answer several questions including: Is there new evidence that early treatments lead to better health outcomes if applied at an early stage?

The USPSTF used a search of electronic databases for a wide variety of studies, including randomized controlled trials (RCTs), meta-analyses, systematic reviews, well-designed observational studies, editorials, and commentaries. They used the search terms “scoliosis,” “idiopathic scoliosis,” “treatment,” and “population-based screening.” The search was limited to adolescents and the English language. Their search found 120 studies, of which 16 were pertinent to the study questions. Of these 16, only 1 study was an RCT. They provided no description of the methods they used to analyze the evidence, although balance sheets and expert consensus were used to form the recommendations.

The RCT compared studies of the effects of exercise alone, exercise and bracing combined, and exercise and electrical stimulation combined.7 The subjects were between 6 and 16 years old, with curves ranging from 15 to 45 degrees. After 12 weeks of treatment, overall improvement was found for all three groups, and no significant difference was found between the different combinations of treatments. The USPSTF also evaluated the results of two cohort studies. One was a long-term retrospective study of patients treated with bracing or surgery, or both, compared with an age-matched, population-based control group.8 The follow-up occurred an average of 22 to 23 years after completion of treatment. Both patient groups responded well in terms of curve progression, and no difference in degenerative spine changes was found between the braced and surgical group, although both groups had more degenerative disc changes than the control group. The USPSTF also considered a multinational, controlled study of bracing, observation, and electrical stimulation.9 Treatment was considered successful if the curve progressed less than 6 degrees by the time the subjects were 16 years of age. A highly significant effect favored bracing over the other 2 treatments. One meta-analysis was available to the USPSTF.10 The analysis (more fully described later in this chapter) included only observational studies, of which only 1 included a control group. The definition of failure was 3 to 10 degrees of progression. Overall, the primary authors conclude that bracing for 23 or more hours per day is the superior treatment for AIS to prevent curve progression.

Given these new studies, the 2004 USPSTF summary5 states they could find no new evidence concerning the effectiveness of screening. They also report that conclusions about treatments are limited by the mixed quality of treatment outcomes studies, including inadequate adjustment for confounding factors, and the lack of health outcomes data. The evidence was rated as fair, defined as “sufficient to determine effects on health outcomes, but the strength of the evidence is limited by the number, quality or consistency of the individual studies, generalizability to routine practice or indirect nature of the evidence on health outcomes.”5 Their recommendation carries a grade of D, recommending against routine screening of asymptomatic patients because of at least fair evidence that screening is ineffective or that harms outweigh the benefits. This conclusion represents the current (U.S.) consensus not to screen routinely for scoliosis in schools, and thus informs public health practice. The question regarding the effectiveness of brace treatment in clinical practice is secondary, although crucial, because screening cannot be justified unless early, effective treatment is available. Recent evidence suggesting that bracing might be effective9,10 was incorporated into the review. Evidence for the clinical effectiveness of brace treatment was not compelling enough to support screening to brace early. Again, insufficient evidence is provided in this review to inform the clinical decision on whether to brace.

Meta-analysis of the Efficacy of Nonoperative Treatments for Idiopathic Scoliosis

Rowe and coworkers,10 as charged by the Prevalence and Natural History Committee of the Scoliosis Research Association, used meta-analysis to determine whether bracing substantially reduces the number of curves that progress to the degree where surgical intervention is warranted. They were interested in the nonoperative options of observation, bracing, and LESS.

The authors began not with a search of electronic databases, but with the bibliography of a major textbook of operative pediatric orthopedics. Three reviewers identified and included 20 studies, including an unpublished prospective, controlled series and an unpublished doctoral dissertation. These were 13 studies of bracing, 6 of LESS, and only 1 of observation. Juvenile (age, < 9 years), immature (age, 10–13 years), and mature patients (age, > 13 years) were included. Braces included the Charleston, Milwaukee, and generic TLSOs. All study designs were included. Nineteen articles were rejected because they included only nonradiographic outcomes, or the data were insufficient regarding treatment, follow-up, or completion rates. They performed a traditional meta-analysis, including categoric and regression analyses of the study findings, which were weighted according to sample size to give more impact to findings from larger numbers of patients.

Three variables were sufficiently described in all studies and were included in the meta-analysis as predictor and outcome variables: level of maturity, definition of progression, and type of treatment. The authors note that the quality scores of the studies increased over time, but that there was no correlation between the year of publication and the effect size found in each study. They did not report the correlation between quality score and effect size. Several problems were found within the individual studies. In some studies, the criteria for failure were unspecified. In others, failure ranged from an increase of 3 to 10 degrees in curve severity. They note that if the typical measurement error is 5 degrees, there is a high likelihood that patients were misclassified as failed. In addition, there was insufficient information concerning the curve type (location of the apex) in the studies.

Rowe and coworkers10 found that the unweighted rate of success in the bracing studies ranged from 57%11 to 100%,12,13

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