Objectives To estimate the time to reach reliable results in a larger group of rheumatologists at onset of their musculoskeletal ultrasound (MSUS) training in modified 7-joints scoring system (US7).
Methods US7 has been shown a useful tool to estimate activity of rheumatoid arthritis (RA) in daily clinical practice. The system has been extensively described including an atlas. Targets of the US7 include synovitis (in B-mode and Power Doppler (BM+PD)), tenosynovitis (BM+PD) and erosive changes of 7 joints (wrist, MCP II+III, PIP II+III, MTP II+V) on the dominant site. We used a modification of the original US7 published, assessing both palmar and dorsal view of MCP and PIP joints. 9 rheumatologists with basic/intermed. level of MSUS underwent a training in general MSUS+US7. At month 1, reliability testing in scoring of static pictures was performed. At months 3 and 12, two reliability-testing sessions were organized. 4 patients with various stages of activity and disease progression of RA were repeatedly scanned, in 2 rounds per session. Sonographers were blind to all patients' data. 2 US machines were used for each session and the setting was fixed before the start. Smoking or drinking alcohol was not allowed. Each patient was investigated by the same US machine in the same daytime in each round of a testing session. Inter-/intra-observer agreement was calculated for each modality of US7 (synovitis score in BM+PD, tenosynovitis score in BM+PD, erosion score) by using non-weighted Cohen kappa (intra-observer agreement) and Light's kappa (inter-observer agreement).
Results At month 1, mean intra- and inter-observer agreement in scoring of static images was reached; κ=0,61 and 0,60 respectively (good). At month 3, mean inter-observer reliability was low (κ<0.2), intra-observer reliability varied within interval κ(0.02;1). As the education continued, mean inter-observer agreement achieved κ=0,6 (good), intra-observer agreement varied within interval κ (0.6;1) (good-excellent).
Conclusions Ultrasound is an operator dependent technique. The level of experience necessary to obtain reliable results in modified US7 (as an example of easy and well determined US method) was achieved after 12 months of low intensity training with direct supervision of a specialist on demand. Low intensity training is in the authors' experience the most frequently used method among beginners in MSUS. Scoring of static images was reliable already after 1 month. Although the probe positions in US7 are well defined, the inter-/intra-observer reliability in scoring of self-obtained images was none in month 3 and the difference leading to good results in month 12 must have been achieved in this later period of training. The difference between higher intra-observer and none inter-observer agreement in month 3 suggests that direct supervision of a specialist in MSUS in this stage of education would lead to quicker progress and better results in achieving reliability among the group members.
Acknowledgement Supported by the project for conceptual development of research organization 023728 and by project no. NT12437.
Disclosure of Interest None declared