Study design and participants
This case-control study was embedded within a larger school-based scoliosis screening program conducted in four provinces in Syria (Damascus, Aleppo, Homs, and Latakia) and included children aged between 7 and 17 years. The screening program involved over 12.645 students from 22 secondary schools. Participants for this case-control study were recruited between October 2022 and June 2023 from randomly selected participating schools without special considerations for regions or grades. The cases were schoolchildren who tested positive for scoliosis during the screening. The controls were those who tested negative and were randomly matched with the cases in a 1:1 ratio, matching for sex, age, height and school. Participants diagnosed with congenital scoliosis, neuromuscular scoliosis or some other scoliosis secondary to identifiable etiologies; been restricted in activities for a long time or exercise excessively; the presence of pain in the region and history of scoliosis surgical treatment were excluded from this study. We excluded the participants diagnosed with congenital scoliosis or neuromuscular scoliosis were excluded from this study to ensure a homogeneous population focused on idiopathic juvenile scoliosis. These conditions have distinct pathophysiological mechanisms and treatment approaches that differ from idiopathic scoliosis, which could confound the results and obscure the specific insights we aimed to gain. The studies involving human participants were reviewed and approved by the Al-Baath University Institutional Review Board (IRB) Committee (No. 048906642).
Simple size
The sample size was determined assuming a prevalence of AIS of 18%11 using the StatCalc module of the Epiinfo 6.0 statistical package for a population of 9423 schoolchildren enrolled in 22 schools in four provinces in Syria (Damascus, Aleppo, Homs, and Latakia). This calculation resulted in a total of 422 schoolchildren to be assessed; this number was increased by 30% in order to account for probable losses, resulting in a sample of 548 schoolchildren.
Screening process
The screening process began with visually inspecting the students upright, looking for signs of spinal misalignment, shoulder/breast asymmetry, and scapula prominence. This was followed by a forward bending test (FBT). If the examiner noted any trunk rotation deformity, a scoliometer was used to quantify the angle of trunk rotation (ATR). Any child with a scoliometer reading of more than 5 degrees or with two or more significant clinical signs was advised to visit a specialized physician for further evaluation. A referral letter recommending a diagnostic standing posteroanterior radiograph of the spine would then be sent to the child’s parents or guardians. This detailed screening process has been previously described in a reference12, which the researchers appear to have used as the methodology in this current study.
Questionnaire
The researchers administered structured questionnaires similarly for both the case and control participants. The students received a face-to-face interview immediately after being screened for scoliosis before receiving their screening results or any recommendations for further follow-up. The students were asked to complete a 31-question questionnaire to collect information on their demographics, lifestyle, and social-environmental characteristics during the interview; this included age, sex, physical activity time, standing and sitting postures, etc. After extensive discussion, the questionnaire was adapted from the Back Pain and Body Posture Evaluation Instrument (BackPEI) and further developed by a team of three orthopaedic surgeons specializing in scoliosis treatment (A.S.Alali, L.D.Alhatem, and M.B.Alsalim), along with experienced screening examiners. The variables included in the questionnaire were selected based on findings from previous studies, the BackPEI instrument, and input from the clinician experts. Subsequently, a pilot study of the assessment form was conducted among 20 volunteer students to analyze the inter-evaluator reliability. The assessment of interexaminer reliability was performed using the intraclass correlation coefficient (ICC), and variables were included in the assessment instrument when obtained ICC values were classified as having good or excellent reliability (ICC ≥ 0.82).
Measurements of outcome and risk factors
Adolescent Idiopathic Scoliosis was diagnosed when a lateral spinal curvature of 10 degrees or greater was detected on a coronal radiographic image; however, since obtaining full spine radiographs for all healthy schoolchildren was not feasible, we used the results of the same standardized school screening protocol from a previous study12, where 80% of children referred for radiographic exams were confirmed to have AIS. We expected a similar accuracy rate for the screening in the current study.
We included a comprehensive assessment of reported risk factors for AIS in their questionnaire, including demographic factors like age, sex, and family history, as well as measures of physical activity, time spent seated, and various postural habits. The questionnaire was adapted from the Back Pain and Body Posture Evaluation Instrument (BackPEI) and translated into Arabic better to reflect the living situations of the Syrian schoolchildren. Visual aids with pictures were provided to help students assess their body postures, which were categorized as ordinary standing, standing with anterior pelvic tilt, or standing with a hunchback.
The questionnaire included detailed assessments of various postural habits, including sitting posture (every day, lean forward/left/right, chest on the desk, crossed legs), sleeping posture (supine, prone, lateral), and school/home desk heights (appropriate, lower, higher). Classroom lighting conditions (appropriate, bright, dark) and eyesight status (standard, myopia) were also evaluated. Additionally, we documented participants’ schoolbag-wearing habits across four categories (backpack on back, backpack on front, shoulder bag, cross-shoulder bag). This comprehensive evaluation of postural behaviours, workspace ergonomics, and environmental factors provided important contextual data for assessing potential risk factors associated with adolescent idiopathic scoliosis in this population.
The questionnaire covered a wide range of potential risk factors, including demographic characteristics like age, sex, and family history, as well as detailed assessments of physical activity levels, postural behaviours (sitting, standing, sleeping), workspace ergonomics (desk heights), environmental factors (classroom lighting), visual health (eyesight), and schoolbag wearing habits. It also gathered data on more specific variables like shoe wear patterns, general health status, height increment, posture-related education, napping, extracurricular activities, low back pain, and sports participation.
Statistical analysis
Given the case-control design of the study, we used conditional logistic regression modelling to evaluate the relative risk of AIS associated with each variable assessed in the comprehensive questionnaire. Odds ratios (ORs) and 95% confidence intervals were calculated to describe the strength of these associations. To examine the independent effects of each factor, a multivariate conditional logistic regression was conducted, with ORs adjusted for age and other significant variables. All statistical hypothesis tests were two-sided, with the threshold for statistical significance set at p < 0.05. The data was analyzed using Stata 15 statistical software.