Development and validation of an OMERACT ultrasound scoring system for the extent of calcium pyrophosphate crystal deposition at the joint level and patient level.

BACKGROUND: The Calcium Pyrophosphate Deposition (CPPD) subgroup of the Outcome Measures in Rheumatology (OMERACT) Ultrasound working group was established to validate ultrasound as an outcome measure instrument for CPPD, and in 2017 has developed and validated standardised definitions for elementary lesions for the detection of calcium pyrophosphate crystals in joints. The aim of this study was to develop and evaluate the reliability of a consensus-based ultrasound scoring system for CPPD extent, representing the next phase in the OMERACT methodology. METHODS: In this study the novel scoring system for CPPD was developed through a stepwise process, following an established OMERACT ultrasound methodology. Following a previous systematic review to gather available evidence on existing scoring systems for CPPD, the novel scoring system was developed through a Delphi survey based on the expert opinion of the members of the OMERACT Ultrasound working group-CPPD subgroup. The reliability of the scoring system was then tested on a web-based and patient-based exercise. Intra-reader and inter-reader reliability of the new scoring system was assessed using weighted Light's κ coefficients. FINDINGS: The four-grade semiquantitative scoring system consisted of: grade 0 (no findings consistent with CPPD), grade 1 (≤3 single spots or 1 small deposit), grade 2 (>3 single spots or >1 small deposit or ≥1 larger deposit occupying ≤50% of the structure under examination in the reference image-ie, the scanning view with the highest grade of depositions), and grade 3 (deposits that occupy more than 50% of the structure under examination in the reference image). The score should be applied to the knee (menisci and hyaline cartilage) and the triangular fibrocartilage complex of the wrist. The intra-reader and inter-reader reliabilities on static images were almost perfect (κ 0·90 [95% CI 0·79-1·00] and κ 0·84 [0·79-0·88]), and on the eight patients recruited (four [50%] female and four [50%] male) were substantial (κ 0·72 [95% CI 0·47 to 0·96] and 0·66 [0·61 to 0·71]). INTERPRETATION: This OMERACT ultrasound scoring system for CPPD was reliable on both static images and patients. The scoring system might be a valuable tool for ensuring valid and comparable results in clinical trials and could help monitor the extent of crystal deposition in patients with CPPD in clinical practice. FUNDING: The Italian Ministry of Health - Ricerca Corrente.

Subclinical ultrasound synovitis in a particular joint is associated with ultrasound evidence of bone erosions in that same joint in rheumatoid patients in clinical remission.

OBJECTIVES: The main aim of this study was to investigate the relationship between ultrasound (US) findings indicative of joint inflammation and US features characterising bone erosions at joint level in patients with rheumatoid arthritis (RA) in clinical remission. METHODS: Twenty-four consecutive patients with RA in clinical remission according to EULAR criteria (DAS28<2.6) underwent a complete clinical assessment. An experienced sonographer blind to the clinical data performed the US examinations to detect and score signs of joint inflammation and bone erosions from second to fifth metacarpophalangeal (MCP) joints of both hands. All joints were scanned both on dorsal and volar aspects. The second and fifth MCP joints were scanned also in lateral aspects. RESULTS: The patients were mainly female (79.2%), with a mean age of 63.2 years ±12.3 standard deviation (SD) and a mean disease duration of 114.5 months ±53.9 SD. Half of the patients were rheumatoid factor positive and 45.8% were anti-citrullinated protein antibody positive. A total of 192 MCP joints and 480 aspects were assessed. Of these joints, 105 (54.7%) were found inflamed by grey-scale US, 57 (29.7%) were power Doppler (PD) positive, and bone erosions were detected in 42 (21.7%) joints. PD signal was found in 30 (53.6%) of the 56 eroded aspects and in only 41 (9.7%) out of the 424 aspects without bone erosions. Both the GS and PD mean scores were statistically higher in the joints with US bone erosions compared to those without erosions. CONCLUSIONS: A higher prevalence of PD signal was found in the joints where bone erosions were detected. This is the first study providing evidence supporting the association between US bone erosions and the persistence of subclinical inflammation in RA patients in clinical remission.