Inter- and intra-reliability of Cobb angle measurement in pediatric scoliosis using PACS (picture archiving and communication systems methods) for clinicians with various levels of experience

Background: Scoliosis is a common spinal malformation, which is typically diagnosed and assessed for severity by measuring the Cobb angle on a plain radiograph. Although manual methods are still considered the gold standard, recent studies have shown that picture archiving and communication systems (PACS) methods have comparable intraobserver and interobserver reliability levels for experienced clinicians. However, there is limited data for these reliability measures using PACS in less experienced medical personnel and radiologist. The objective of this study was to determine if inter- or intra-reliability differs for clinicians with different experience levels and if PACS provides adequate inter- or intra-reliability. Methods: Ten radiographic images of scoliosis patients were obtained via a retrospective chart review. After a brief training exercise, Cobb angle measurements were performed twice on each radiograph, separated by one week, using the PACS method. Subject groups included medical students, orthopedic resident physicians, orthopedic surgeons and radiologists. Each subject group had two participants (R1 and R2). Each participant calculated a Cobb angle using the PACS method at Week 1 and Week 2 (W1 and W2). Intrarater reliability was calculated by comparing each rater's W1 and W2 measurements, inter -rater reliability within each experience level was calculated by comparing R1 and R2's measurements at W1 and W2, and inter -rater agreement was found by comparing one participant's W1 measurement to participants W1 measurement from another group. Results: Resident physicians, orthopedic surgeons, and radiologist subject groups had significant levels of interrater reliability within -groups (r=0.946, 0.968, 0.967, P<0.01) and between groups. Additionally, for all these three groups, individual intra-rater reliability levels were high (r=0.973, 0.976, 0.954, 0.977, 0.974, 0.913, P<0.01). Only inexperienced medical student raters had poor within -group and between -group interrater reliability measures (r=-0.176, -0.188, -0.071, -0.188, P>0.05). However, individual intra-rater reliability levels were high (r=0.919, 0.592, P<0.05). Conclusions: PACS is a reliable method of measuring Cobb angles in most experience levels. For inexperienced medical students, interrater reliability within -groups and between groups are not statistically significant, highlighting medical students lack expertise in in calculating cobb angles. However, individual intra-rater reliability levels were high for medical students, validating the use of PACS as a consistent method for calculating Cobb angles.