Improving the Effectiveness of Adolescent Idiopathic Scoliosis (AIS) Screening: A Prospective Study

Diagnostic accuracy study.

To evaluate the diagnostic performance of a combined screening method for adolescent idiopathic scoliosis (AIS), integrating scoliometer-based Angle of Trunk Rotation (ATR) measurement with physical examination findings, and to determine optimal screening thresholds.

The scoliometer and Adam Forward Bending Test (FBT) are widely used in AIS screening, but the optimal ATR cutoff and the additive value of clinical signs remain debated. Accurate and efficient school-based screening is essential for early detection and timely intervention.

This study included 595 participants (458 with AIS and 137 without scoliosis). Screening involved visual inspection, Adam Forward Bending Test (FBT), and Angle of Trunk Rotation (ATR) measurement. Diagnostic confirmation was performed using a standing whole spine x-ray or spine ultrasound. Receiver operating characteristic (ROC) analysis and logistic regression were used to identify the best predictive combination of ATR thresholds and clinical signs.

Among the 595 participants, the mean Cobb angle was 21.0˚±8.1˚ for AIS patients and 4.0˚±4.0˚ for non-AIS individuals. An ATR cutoff of 5.5 degrees yielded an AUC of 0.72, with a sensitivity of 73.1% and specificity of 70.8%. Combining ATR ≥5.5 degrees with at least 3 clinical signs (head tilt, shoulder unlevel, waistline asymmetry, and pelvic prominence) improved sensitivity to 84.1% (AUC=0.694). For clinical implementation, a simplified threshold of 5 degrees combined with/or ≥ 3 clinical signs further increased sensitivity to 91.5%, with acceptable specificity (47.4%). Among patients with Cobb angles ≥20 degrees, 10.3% had an ATR <6 degrees, emphasizing the role of clinical signs in identifying severe cases. In sex-specific analyses, girls showed higher sensitivity (89.7%) at an ATR cutoff of 4.5 degrees, compared with boy who had a cutoff of 5.5 degrees, while boys exhibited sensitivity improved when clinical signs were added. A unified threshold of ATR ≥6 degrees combined with/or ≥ 4 clinical signs achieved a sensitivity above 90% for both sexes in detecting severe scoliosis, supporting its practical value for school-based screening.

Combining ATR with clinical signs substantially enhances AIS screening performance. A practical strategy of ATR ≥5 degrees combine with/or ≥ 3 clinical signs offers balanced sensitivity and specificity for general screening. For detecting severe scoliosis, ATR ≥6 degrees combine with/or ≥ 4 clinical signs is recommended. This structured protocol supports more accurate, sex-adapted and severity-adapted school-based AIS screening.