Objective: Musculoskeletal ultrasound (US) is more sensitive than physical examination in detecting synovitis and helps physicians to understand its pathophysiology. In this study, we aimed to determine if the experience in musculoskeletal US scanning is independently associated with improved physical examination skills to detect synovitis.
Method: Seventy patients with rheumatoid arthritis and twenty-three physicians were enrolled. Patients were first assessed by multiple physicians with a range of clinical/sonographic experience for the swelling of the wrist, metacarpophalangeal and proximal interphalangeal (PIP) joints and next underwent US assessment performed by another physician experienced in musculoskeletal US. We then calculated the positive/negative predictive values (PPV/NPV) of joint swelling to identify US-detected synovial hypertrophy. Finally, the factors independently associated with the accuracy of clinical assessment were identified by using multivariate analyses.
Results: One thousand five hundred forty joints were assessed 6116 times in total for swelling. Overall, PPV and NPV of joint swelling were 51.7% and 88.3%, respectively. Multivariate analyses identified wrist joint, tenderness, male and greater patients' age as the factors significantly associated with higher PPV. In addition, there was a trend that longer experience in rheumatology clinical practice was associated with higher PPV (p = 0.058). On the other hand, longer experience in musculoskeletal US, PIP joint and positive rheumatoid factor were identified as the significant factors for higher NPV, while wrist joint, tenderness, presence of osteophyte and obesity as those for lower NPV.
Conclusion: Our data suggest that the experience in musculoskeletal US improves physical examination skills particularly to avoid overestimation.Key Points• Physicians with longer US experience are less likely to overestimate synovitis by physical examination.• Musculoskeletal US is a useful tool for rheumatologists to improve their physical examination skill.• Presence of osteophytes, joint tenderness and obesity influence the accuracy of physical examination of joints.
Keywords: Musculoskeletal ultrasound; Physical examination; Rheumatoid arthritis; Swollen joint; Synovitis.