Pos1362 Ultrasound of the Forefeet Next to the Hands and Wrists for the Detection of Subclinical Joint-Inflammation in Patients at Risk for Ra: Is It Necessary?

Background: Musculoskeletal Ultrasound (US) can be useful to detect subclinical joint-inflammation in patients with clinically suspect arthralgia (CSA) as inflammatory arthritis (IA) is by definition absent. Hands, wrists and forefeet are usually scanned, but it is unclear if the forefeet have additional value in the prediction of arthritis development on top of hands and wrists. Objectives: To explore the possibility to omit the forefeet and shorten scanning time, the additional value of US of the forefeet in CSA patients was determined. Methods: 298 consecutively included CSA patients of two independent cohorts (CSA Rotterdam and SONAR; cohort 1 and 2) underwent US of the hands (MCP2-5, PIP2-5), wrists and forefeet (MTP2-5) at baseline. All joints were scored according to the EULAR-OMERACT US guidelines. US-positivity was defined as Gray Scale (GS)≥2 and/or Power Doppler (PD) ≥1. Patients were followed for a maximum of 2 years for IA development. We analyzed the association between IA development and US-positivity in i) the full US-protocol (hands, wrists, forefeet), ii) the full US-protocol with correction for GS-findings in the forefeet of healthy individuals (scored positive only if GS ≥3 for MTP2/3) and iii) the protocol without the forefeet (hands and wrists only). Area under the receiver operator curves (AUROCs) were compared. Results: In CSA patients with a positive US, subclinical joint-inflammation was most often present in the hands and/or wrists: 86% and 90% in cohort 1 and 2, respectively. Only a small proportion of patients had subclinical joint-inflammation in the forefeet only (14% and 10%, respectively). When using the full US-protocol, US-positivity was associated with IA development in both cohorts (HRs 2.6, 95% CI 0.91-7.5 and 3.1, 95% CI 1.5-6.4; Figure 1). Additional correction of GS in the forefeet showed similar results. Evaluation of the hands and wrists only (without the forefeet) did not change results in both cohorts (HR 3.1, 95%CI 1.4-6.9 and 2.8, 95%CI 1.4-5.6; Figure 1). The AUROCs were comparable between the full protocol and the protocol without the forefeet (0.60 versus 0.67 in cohort 1 and 0.67 versus 0.65 in cohort 2). Conclusion: The forefeet can be omitted when US is used for the prediction of IA development in CSA patients. This is due to the finding that subclinical joint-inflammation in the forefeet without concomitant inflammation in the hands/wrist is infrequent. These results allow a shorter US examination. REFERENCES: NIL. Acknowledgements: NIL. Disclosure of Interests: None declared.