Risk Progression in Adolescent Idiopathic Scoliosis: Literature Review and Scale Proposal

Results: After verification of the 46 articles, nine risk factors were identified: Curve Magnitude at Presentation, progression at 1 year, Risser's signal, waiting time for surgery, type of curve, rotation of the apical vertebra, thoracic kyphosis, selfimage, and spinopelvic balance. Curve Magnitude at Presentation is the most important predictive factor of progression. The Scale SSS-IOT (Scoliosis Severity Score-I) was developed, assigned to each of the above criteria, with a higher score for worse prognosis factors and the lowest score for lower risk of progression or better prognosis factors. The final result is the sum of the scores in a single query.


Introduction
Adolescent idiopathic scoliosis (AIS) is a three-dimensional deformity of the vertebral column, marked by the rotation of the vertebral bodies in the axial plane and deviation in the coronal plane of 10 degrees. Its manifestation occurs predominantly between 10 and 18 years, usually does not cause pain or neurological alterations, however, it generates a large impact in physical and psychosocial aspects [1]. It is the most common deformity of the spine, affecting from 0.5% to 3% of the school-age population. The female gender is predominant, being 2: 1 in general and 8: 1 in the most severe cases, requiring surgical correction [2][3][4].
In most countries with public health services, due to the increasing demand and difficult access to resources essential for surgery, such as instrumental, neurophysiological follow-up, need for ICU beds, high cost, low number of qualified surgeons, there are long queues [5]. Júnior et al. (2011) studied the waiting list for surgical treatment of AIS in a public hospital in São Paulo and found 51 patients waiting for 2 to 180 months [6]. In Hospital das Clínicas of São Paulo, the biggest public hospital in Latin America, in 2019 scoliosis surgery waiting list reached 281 cases with minimum waiting time of 4 years.
The risk of progression of the curves increases without intervention from diagnosis to skeletal maturity [7]. Girls of pubertal age (10,11,12 years) who present curves above 30 degrees at diagnosis are prone to progress in 90% to 100% of cases [8].
The natural evolution of idiopathic scoliosis was extensively studied and several risk factors were analyzed to determine the risk of progression in different populations [9][10][11]. Despite the efforts, there is still no practical tool that uses the risk factors to estimate the progression and prognosis of the disease. Lostein and Carlson (1984) proposed an arithmetic formula to predict the scolioses progress, using the Risser's sign, the Cobb angle and chronological age, but the formula was not reproducible in other populations [12]. In the current public health scenario, patients wait months to years for surgery in a list formed by order of entry. It is estimated that many of the patients had a significant progression of the diagnosis, with more severe and rigid curves at the time of surgery, resulting in longer surgeries, longer hospitalization and greater need for additional surgery. In this logic, the patient who presents the best benefit of surgical treatment is one that has a higher potential for scoliosis progression.
The aim of this review is to identify the main risk factors for the progression and prognosis of AIS according to the current literature and create a score that helps to identify patients with greater potential for the increases of who are at risk for rapidly progressing scoliosis waiting list of patients' candidates for surgery. We consider that surgery may benefit patients that are in risk of progression more than patients that have slow progression or have already progressed. This could organize waiting lists like occurs in liver tranplatation tha uses MELD score system [13].

Materials and Methods
A review protocol was delveloped using Prefered Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) Checklist. A systematic search was performed in the bibliographic databases PubMed, Google Scholar, and Bireme databases, using the following descriptors (MeSH terms): Scoliosis AND Adolescent AND risk AND progression. Search terms expressing "Adolecent Scoliosis" were combined with search terms as "progression" or "risk progression" conducted by an experient author, and backwards citation of obtained articles. Search were restricted to studies with humans, without date limit, of any desing, abstract must be in English. The survey was conducted in September 2017. Two reviewers (AHO and RMM) independently screened titles, abstracts and full text articles indentified by the literature search. All Full Text articles were selected for further selction of eligibility.
Mini Abstract/Précis: Adolescent idiopathic scoliosis is a vertebral column deformity, which increases without intervention. A systematic search was performed to identify risk factors for the AIS progression and create a tool to identify potential developers of serious scoliosis. We identified 9 risk factors and developed a simple scale called Scoliosis Severity Score-I. Journal of Orthopaedics and Physiotherapy Volume 4 | Issue 1

Eligibility criteria
It was included review studies, clinical trials, prospective case series, retrospective observational studies, and cross-sectional studies with full text available. Case series type study, preliminary protocols, editorials and conference presentations were excluded.
We excluded articles without abstract available on the digital platform, articles related to other types of scoliosis like degenerative, neuromuscular or congenital, genetic studies, laboratorial studies, in vitro studies, post-operative studies and studies performed after skeletal maturity.

Studies selection
Previous articles were selected by titles, excluding those not included in the eligibility criteria, duplicate or irrelevant articles for the subject, considering risk factors for progression to adolescent idiopathic scoliosis, based on anthropometric data, questionnaires, and simple radiographs, without the need for further examination. After sorting by title, Full-Text of the remaining articles were reviewed by AHO and RMM.

Ethical Approval
This study obtained approval from the Ethics and Research Committee Review Board. And online protocol were registred in Plataforma Brasil. The search resulted in 280 citations in PubMed, 268 in Bireme and 16,400 in Google Scholar. We consider the titles of the 500 most relevant Google Scholar. After the exclusion of duplicate articles, 83 were selected for the relevance of titles and abstracts. Of these, 46 were selected because they met the inclusion criteria and were read in full. Three articles, one Italian, German and Chinese, required the translation of the full text, carried out in the Google Translate ® tool. The article selection process is summarized in Figure 1.

Results
The selection criteria were 22 prospective case series, 19 retrospective observational studies, 2 reviews, and 3 cross-sectional studies.

Selection Biases
The articles were selected by a single author, which can represent losses of works considered of little relevance by the same one.
It was not possible to conduct a meta-analysis due to the diversity of methodologies and selection criteria of the selected studies.
No specific evaluation was carried out on the quality of the articles included since it was intended to include as many articles as possible on the subject.

Risk factors
After verification of the 46 articles, nine risk factors that directly interfere with the evolutionary prognosis of the disease were identified: Curve Magnitude Scoliosis at Presentation, progression at 1 year, Risser's signal, waiting time for surgery, type of curve, rotation of the apical vertebra, thoracic kyphosis, self-image, and spinopelvic balance. Table 1 shows the main adolescent idiopathic scoliosis risk factors identified from the literature review.   Journal of Orthopaedics and Physiotherapy

Curve Magnitude Scoliosis at Presentation
The curve magnitude of scoliosis at presentation is the most important predictive factor in determining the progression of a scoliotic curve above 30 degrees. An initial Cobb angle of 25 had a positive predictive value of 68.4% and a negative predictive value of 91.9% for scoliosis progression for curves above 30 degrees, the initial minimum value to determine the progression of the curve in the treatment of long-term scoliosis [14]. A lower percentage of correction and a greater number of complications is expected for larger curves at the presentation in skeletally immature patients [9]. The maximum Cobb final angle of a curve is directly correlated with the initial angle [3,8,9,[14][15][16]. Duval-Beaupère and Lamireau (1985) followed 139 patients with AIS, all with lower major curves of 30 degrees, 83% of these patients had a progression lower than 6 degrees, not requiring surgery [28].

Progression at 1 year
The progression of more than 5 degrees every 6 months is a strong predictor of the progression of the curve. Patients who are being treated with vest and show a progression between 6 and 10 degrees, representing a warning sign for possible failure. The progression of more than 10 degrees means failure of this treatment and general indication of surgery [17,18].
Curves that progressed from 6 to 10 degrees per year needed to be operated in 70.9% of cases, while those who progressed more than 10 degrees in 1 year required surgery in 100% of cases [8,[19][20][21][22].

Skeletal Maturity (Risser)
The Risser's signal is easily identifiable on panoramic radiographs of patients with scoliosis in the frontal incidence. This sign is a well-known marker of bone growth. Patients in stages 0, 1 and 2 had a higher growth potential and were slower in phases 3, 4 and 5. A meta-analysis considering 4 studies and 1,891 patients demonstrated a statistically significant association of Risser 0 and 1 with the progression of the curves of scoliosis, with odds ratio ranging from 1.5 to 5.1 (p < 0,001) [23].
Patients who were on the waiting list for surgery for more than six months had a worse correction, more complications, and those who waited less than six months required fewer reoperations, presented greater correction capacity with fewer complications [24].
The longer waiting time was associated with the lower score in the SRS quality of life questionnaire (0.13 points for 6 months, are twice as likely to progress [11,21].

Self-image
Self-image is an important factor in the quality of life of patients with idiopathic scoliosis, self-imprinting of an underdeveloped body can become one of the greatest relationship difficulties, low self-esteem and depression, as well as thoughts of suicidal ideation greater than control groups [26]. Untreated correctly scoliosis can cause significant psychosocial problems due to the adverse effects of the disease on body image [27]. Conservative treatments like the use of vest can exacerbate these problems. The psychological impact of using different types of data was validated through a quality of life questionnaires, showing that the patient with idiopathic scoliosis of adolescents is more likely to develop dissatisfaction with their body image [28,29]. Untreated scoliosis has potential effects such as pain, deformity, loss of lung capacity in more severe forms [10]. Few studies compare their physical and social restrictions with aspects related to loss of self-esteem [30]. However, when operated on, patients of both sexes are able to show improvement in the scores of mental health questionnaires [31]. Therefore, the effects of scoliosis on the patient's self-image and social life, despite being a subjective criterion, should be considered as a prognostic factor for the disease.  Apical vertebra Nash Moe > 3 1

Design of the Scale
Lenke C 1

Self-image
No aesthetic concern 0 Moderate aesthetic concern 1 High esthetic concern 2 Thoracic Kyphosis After the selection and verification of the scientific evidence, the Scoring Scale was developed for the risk stratification of patients with AIS. A simple score was assigned to each of the above criteria, with a higher score for worse prognosis factors and the lowest score for lower risk of progression or better prognosis factors. We atribuited 1, 2 or 3 points according to severity. Each variable receives a score and the final result is the sum of the scales assigned in a single query. The initial Cobb is based on the medical records or the first radiograph that led the patient to inclusion in the queue.
Imaging tests available in electronic medical records as well as information contained in the medical records can be used to search for required information. Table 2 shows the scale created, called Scoliosis Severity Score-I (SSS-IOT).

Discussion
Each of the prognostic criteria was supported by consistent scientific evidence and most of the results of the articles were convergent. Most of the studies analyzed are prospective case series, probably due to the great number of ethical impediments in performing randomized clinical trials with patients with AIS. The authorization of parents and guardians is mandatory and the concern for the welfare of the adolescent should be the priority. We found many retrospective studies with expressive numbers of patients, also with convergent results. The criteria "Curve Magnitude at Presentation" was unanimous, being perhaps the most important prognostic factor in this disease.
Due to the importance of sagittal balance in adult scoliosis, this parameter was the subject of several studies in AIS. The articles that analyzed it showed divergent results. The largest series of cases, 60 patients, showed that the relevance of sagittal balance in adolescents is not the same as in adult scoliosis. In these cases, this variable was not considered a prognostic factor.
Other risk factors related to the progression of scoliosis were identified. However, they were excluded from the scale proposed by the need for complementary tests, such as bone densitometry and genetic tests. In addition to being expensive and of low specificity, they were used in studies with low level of evidence or methodological failures [12,23]. Sanders et al. published in 2008 a score using the simplification Turnner-Whitehouse III RUS score that uses ephysial status of proximal, distal and medial phalangeal of 2 ulnar fingers (forth and fifth fingers), with good interobserver and intraobserver reliability, and good curve prediction considering girls with adolescent idiophatic scoliosis. Despite the good reliability and strong prediction value we didn't considered this score, due difficult of learning curve, and need of hand x-ray, what difficult assessment in clinical practice, raise costs and radiation exposure [32]. Our score objectives are to be as simple as possible and to consider other prognostic risks like self image, rotation, kyphosis and others factors that could impact not only curve progression but quality of life. Other factors related to skeletal maturity such as chronological age and menarche, already contemplated by Risser's sign and directly correlated, were also excluded, since they could make the scale redundant in order to obtain a scale that can be easily applied in single consultation, and in health services of various levels of complexity, with only an initial and current lateral radiograph, we use only simple criteria that are part of the AIS basic semiology and propaedeutics.
Waiting lists for surgeries are common in all countries with a public health system. They generate public dissatisfaction and political concern, in part because they cause prolonged suffering, worsening of the pathological condition, pain and, in some cases, the death of their patients [33]. According to the 2017 estimate of the SISREG (Brazilian Federal Government Regulation System), more than 800 thousand people are waiting for some type of elective surgery by the Unified Health System, most of them orthopedic [34]. Doctors and patients have the perception that waiting lines are not fair, and this exacerbates dissatisfaction [35].
The scale created has limitations and cannot be generalized. It was not possible to define mathematically which of the nine criteria had greater influence or greater importance in the prognosis of AIS. This would require complex calculations, which would make it difficult to scale. In addition, the points were given empirically, considering that the risk factors do not present the same value between them. Due to the diversity of methodologies adopted, a qualitative analysis of the studies was not performed, which invalidated the meta-analysis execution.
regional characteristics needs and can be modified and improved over time. Our scale were developed only for research purposes and were not implement in our patients or institution.
Studies with clinical correlation are necessary for its implantation. The adoption of criteria for the organization of the surgical row for scoliosis aims a better serve the patients who would have greater benefits, fewer risks for surgical treatment, with better costeffectiveness. These aspects should be the object of future studies. Scale could be improved during time according future concernings and sugestions.