P246 Revision to musculoskeletal domain of BILAG-2004 index to incorporate ultrasound findings

Background/Aims The BILAG-2004 index grades musculoskeletal (MSK) inflammation as mild (C), moderate (B) and severe (A), based on clinical features. In a recent study, 27% of SLE patients with MSK pain have ultrasound (US) synovitis without swelling, and respond better to therapy than those with normal ultrasound. We aimed to revise the MSK domain of the BILAG-2004 index to improve its utility in modern practice. Methods An MSK sub-committee reviewed the existing BILAG-2004 MSK definitions and glossary, then re-analysed data from recent studies to propose revised definitions. Results The new definitions/changes are: (i) BILAG-C arthralgia (if US is not performed) is defined as a classical inflammatory symmetrical small-joint distribution of symptomatic joints on clinical assessment, based on the features most associated with US inflammation in a previous study. If US is performed, all previous BILAG-C patients are reclassified: (ii) BILAG-B now includes patients without swelling if they have significant synovitis/tenosynovitis on US in symptomatic joints/tendons; (iii) patients with arthralgia without swelling are scored as BILAG-D instead of C, if US of the symptomatic joints has been performed and is normal; (iv) a more detailed definition of functional impairment is provided for BILAG-A. Data from 221 symptomatic SLE patients (BILAG-A-C) in two recent studies were re-analysed in the light of the above changes. 121/221 (54.8%) were graded clinically as having arthralgia / myalgia (BILAG-C) on BILAG-2004 . Of these, 53/121 (43.8%) had evidence of synovitis (GS > 1 or PD > 0) or tenosynovitis (GS > 0 or PD > 0) on US. The effect on grading if US were performed on all BILAG C cases is shown in table 1. Conclusion Future versions of the BILAG index will allow the use of US to classify patients who are graded as mild inflammatory arthritis (BILAG-C) to moderate (BILAG-B) or non-inflammatory pain (BILAG-D/E). Although US is not required for all assessments it may be used when there is diagnostic uncertainty. This is in keeping with clinical practice in inflammatory arthritis care, and similar to use of other investigations (e.g. renal biopsy) that contribute to BILAG assessments of other systems. Disclosure R.D. Sandler: None. E.M. Vital: None. A. Prabu: None. C. Riddell: None. K.I. Mahmoud: None. L. Teh: None. C.J. Edwards: None. C. Yee: None.