An Inter- and Intra-Rater Agreement Assessment of Two Novel Classification Systems for Coronal Imbalance in Adult Scoliosis and Spine Deformity

Abstract

Objective: Coronal malalignment is a common feature of adult spinal deformity, and accurate classification is essential for diagnosis and treatment planning. However, variations in interpretation among clinicians can impact classification consistency. By assessing the reliability and applicability of these systems across different medical experts, this study seeks to establish a standardized approach to enhance clinical outcomes. This study aimed to evaluate the inter- and intra-observer agreement of two classification systems for coronal malalignment in adult spinal deformity patients, as proposed by Qiu et al. and Obeid et al.

Methods: We analyzed 70 cases of adult spinal deformity collected between January 1, 2010, and April 20, 2023, using the classification systems proposed by Qiu et al. and Obeid et al. To assess inter- and intra-rater agreement, the same group of researchers re-evaluated all cases in a random order after a 4-week interval. We used the kappa statistic (κ) for inter- and intra-rater agreement assessment.

Results: Qiu's classification system: Inter-rater agreement: Substantial agreement (κ = 0.76; 95% CI: 0.72–0.80) for Type A, Type B, and Type C. Intra-rater agreement: Nearly perfect agreement (κ = 0.83; 95% CI: 0.78–0.89) within raters for Type A, Type B, and Type C.Obeid's classification system: Inter-rater agreement: Almost perfect agreement (κ = 0.85; 95% CI: 0.83–0.87) for Type 0, Type 1, and Type 2. Complete system: Substantial agreement (κ = 0.68; 95% CI: 0.65–0.71) for all types and subtypes. Intra-rater agreement: Almost perfect at the type level (κ = 0.88; 95% CI: 0.83–0.93) and substantial at the subtype level (κ = 0.75; 95% CI: 0.65–0.85).

Conclusions: The research findings indicate a high level of agreement between the classification system described by Qiu et al. and the classification system proposed by Obeid et al. This agreement supports the widespread adoption and utilization of these classification systems in future clinical studies.

Keywords

adult spinal deformity / agreement study / coronal malalignment / reliability / reproducibility

References

[1] P. Rajnics, A. Templier, W. Skalli, F. Lavaste, and T. Illés, “The Association of Sagittal Spinal and Pelvic Parameters in Asymptomatic Persons and Patients With Isthmic Spondylolisthesis,” Journal of Spinal Disorders & Techniques 15 (2002): 24-30.

[2] C. Barrey, P. Roussouly, J. C. Le Huec, et al., “Compensatory Mechanisms Contributing to Keep the Sagittal Balance of the Spine,” European Spine Journal 22, no. Suppl 6 (2013): S834-S841.

[3] S. Kotwal, M. Pumberger, A. Hughes, and F. Girardi, “Degenerative Scoliosis: A Review,” HSS Journal 7 (2011): 257-264.

[4] J. P. Thompson, E. E. Transfeldt, D. S. Bradford, et al., “Decompensation After Cotrel-Dubousset Instrumentation of Idiopathic Scoliosis,” Spine 15 (1990): 927-931.

[5] C. Barrey, P. Roussouly, G. Perrin, and J. C. le Huec, “Sagittal Balance Disorders in Severe Degenerative Spine. Can We Identify the Compensatory Mechanisms?,” European Spine Journal 20, no. Suppl 5 (2011): 626-633.

[6] Y. M. Baghdadi, A. N. Larson, M. B. Dekutoski, et al., “Sagittal Balance and Spinopelvic Parameters After Lateral Lumbar Interbody Fusion for Degenerative Scoliosis: A Case-Control Study,” Spine 39 (2014): E166-E173.

[7] K. Abelin-Genevois, “Sagittal Balance of the Spine,” Orthopaedics & Traumatology, Surgery & Research 107 (2021): 102769.

[8] M. Pumberger, F. Schitz, J. Burger, et al., “Kyphoplasty Restores the Global Sagittal Balance of the Spine Independently From Pain Reduction,” Scientific Reports 10 (2020): 8894.

[9] K. Abelin, R. Vialle, T. Lenoir, C. Thévenin-Lemoine, J. P. Damsin, and V. Forin, “The Sagittal Balance of the Spine in Children and Adolescents With Osteogenesis Imperfecta,” European Spine Journal 17 (2008): 1697-1704.

[10] J. Fechtenbaum, A. Etcheto, S. Kolta, A. Feydy, C. Roux, and K. Briot, “Sagittal Balance of the Spine in Patients With Osteoporotic Vertebral Fractures,” Osteoporosis International 27 (2016): 559-567.

[11] Q. Yong, W. Bin, and Z. Feng, “Classification of Coronal Trunk Imbalance in Degenerative Lumbar Scoliosis and Its Influence on Osteotomy Strategy,” Chinese Journal of Orthopaedics 29 (2009): 418-423.

[12] H. Bao, P. Yan, Y. Qiu, Z. Liu, and F. Zhu, “Coronal Imbalance in Degenerative Lumbar Scoliosis: Prevalence and Influence on Surgical Decision-Making for Spinal Osteotomy,” Bone & Joint Journal 98-B (2016): 1227-1233.

[13] Z. Zhang, T. Liu, Y. Wang, Z. Wang, and G. Zheng, “Factors Related to Preoperative Coronal Malalignment in Degenerative Lumbar Scoliosis: An Analysis on Coronal Parameters,” Orthopaedic Surgery 14 (2022): 1846-1852.

[14] A. Kiram, Z. Hu, G. C. Man, et al., “The Role of Paraspinal Muscle Degeneration in Coronal Imbalance in Patients With Degenerative Scoliosis,” Quantitative Imaging in Medicine and Surgery 12 (2022): 5101-5113.

[15] I. Obeid, P. Berjano, C. Lamartina, D. Chopin, L. Boissière, and A. Bourghli, “Classification of Coronal Imbalance in Adult Scoliosis and Spine Deformity: A Treatment-Oriented Guideline,” European Spine Journal 28 (2019): 94-113.

[16] M. A. Rotondi and A. Donner, “A Confidence Interval Approach to Sample Size Estimation for Interobserver Agreement Studies With Multiple Raters and Outcomes,” Journal of Clinical Epidemiology 65 (2012): 778-784.

[17] J. R. Landis and G. G. Koch, “The Measurement of Observer Agreement for Categorical Data,” Biometrics 33 (1977): 159-174.

[18] F. Schwab, A. Dubey, L. Gamez, et al., “Adult Scoliosis: Prevalence, SF-36, and Nutritional Parameters in an Elderly Volunteer Population,” Spine 30 (2005): 1082-1085.

[19] M. P. Kelly, J. D. Lurie, E. L. Yanik, et al., “Operative Versus Nonoperative Treatment for Adult Symptomatic Lumbar Scoliosis,” Journal of Bone and Joint Surgery (American) 101 (2019): 338-352.

[20] J. S. Smith, M. P. Kelly, E. L. Yanik, et al., “Operative Versus Nonoperative Treatment for Adult Symptomatic Lumbar Scoliosis at 5-Year Follow-Up: Durability of Outcomes and Impact of Treatment-Related Serious Adverse Events,” Journal of Neurosurgery: Spine 35 (2021): 1-13.

[21] S. D. Glassman, S. Berven, K. Bridwell, W. Horton, and J. R. Dimar, “Correlation of Radiographic Parameters and Clinical Symptoms in Adult Scoliosis,” Spine 30 (2005): 682-688.

[22] Z. Zhang, K. Song, B. Wu, P. Chi, Z. Wang, and Z. Wang, “Coronal Imbalance in Adult Spinal Deformity Following Posterior Spinal Fusion With Instrument: A Related Parameters Analysis,” Spine 44 (2019): 550-557.

RIGHTS & PERMISSIONS

2025 The Author(s). Orthopaedic Surgery published by Tianjin Hospital and John Wiley & Sons Australia, Ltd.