Intraobserver Reliability on Classifying Bursitis on Shoulder Ultrasound

Abstract

Purpose: Bursitis is a common musculoskeletal cause of shoulder pain and treatment varies, thus correctly diagnosing and grading bursitis is paramount in deciding management. Our aim was to assess reliability in grading shoulder bursitis on ultrasonography among fellowship trained musculoskeletal radiologists at our institution. Methods: Retrospective study of patients diagnosed with bursitis on ultrasonography. Single-sonographic images of the subacromial-subdeltoid bursa were collected for each patient and randomized to form a test-bank of varying degrees of bursitis. Three months after the test was administered, the cases were randomized and readministered. The radiologists graded each case as: within normal limits, mild, moderate or severe. Intraobserver variability was measured using Cohen's kappa coefficient. Linear regression model was performed to assess correlation between years of experience and kappa. Results: 10 radiologists reviewed 70 cases of bursitis. Kappa values ranged from .53 to .91, indicating 'moderate' to 'almost perfect' variability amongst radiologists. A moderate positive correlation of improving variability (r = .69) with increasing years of experience exists. Conclusion: Fellowship trained musculoskeletal radiologists were able to grade shoulder bursitis with moderate to almost perfect variability, with a positive correlation of improved variability with increasing experience. This may help clinicians choose the correct treatment more confidently in their patients with shoulder pain.

Keywords: intraobserver variability; shoulder bursitis; ultrasonography.