Background/Purpose: Treat-to-target (T2T) strategies have significantly improved outcomes in early rheumatoid arthritis (RA). Treatment escalation is usually guided by a disease activity score; however, modern imaging techniques demonstrate that many patients have sub-clinical synovitis without clinical joint swelling, and DAS28 scores can be elevated in patients without active RA. The TASER study (NCT00920478) is a randomized controlled trial comparing a standard T2T strategy with one guided by DAS28 and musculoskeletal ultrasound (MSUS)

Objective: To report the frequency of sub-clinical MSUS synovitis in patients randomized to the MSUS arm of the TASER study, and to determine how frequently treatment decisions could be affected by using MSUS

Methods: DAS28 scores were calculated every month. MSUS was performed on patients in low disease activity (DAS28<3.2) and those with moderate disease activity (3.2≤DAS28<5.1) in the absence of clinically swollen joints (SJ ≤1). 14 joints (bilateral PIP2+3, MCP2+3, radiocarpal, MTP2+5) were assessed. Active disease was defined as >2 joints demonstrating any Power Doppler (PD) signal

Analysis: Paired DAS28 and MSUS data from 319 assessments were pooled to determine levels of agreement between clinical and MSUS findings

Results:

Cohort: 60% female, mean age 57 years (SD13), mean disease duration 5.1 months (SD2.8), 66% rheumatoid factor positive, 66% anti-CCP antibody positive, 32% erosive baseline Xrays

Table 1: Comparison of DAS28 and MSUS findings; agreement is shown in italics, disagreement in bold

	Number of Instances	MSUS Findings N (%)		Overall Agreement
		Active Disease	Inactive Disease
Remission (DAS28 < 2.6)	149	42 (28%)	107 (72%)	72%
Low disease activity (DAS28 < 3.2)	284	78 (27%)	206 (73%)	73%
Moderate disease activity (3.2≤DAS28<5.1) AND ≤ 1 Swollen Joint	35	14 (40%)	21 (60%)	40%

27-28% of patients in clinical remission/low DAS28, demonstrated evidence of sub-clinical synovitis. In 60% of patients with moderate disease in the absence of clinical synovitis there was no MSUS synovitis either. Overall, using MSUS or a DAS28>3.2 threshold for DMARD escalation would have reached the same decision on 220 out of 319 occasions (69% agreement)

Table 2: Frequency (%) of positive MSUS findings in individual joint areas

Joint Area (pooled data for both sides)	Synovial Hypertrophy N (%)	PD Signal N (%)
PiP2	30 (9%)	13 (4%)
PiP3	20 (6%)	3 (1%)
MCP2	105 (33%)	74 (23%)
MCP3	69 (22%)	42 (13%)
Radiocarpal	235 (74%)	179 (56%)
MTP2	212 (66%)	23 (7%)
MTP5	26 (8%)	16 (5%)

For all instances, mean SH score = 4.0 (SD3.5) and index = 2.2 (SD1.7). Mean PD score = 1.4 (SD1.8) and index = 1.1 (SD1.2)

Conclusion: Assessment of global disease activity using a limited MSUS joint set may allow further tailoring of DMARD therapy by: 1. supporting DMARD escalation in patients with active disease despite a reassuring DAS28 and 2. preventing DMARD escalation in patients with moderate DAS28 levels but minimal evidence of active disease. MSUS findings in the radiocarpal and index MCP joints were most likely to influence DMARD escalation decisions. Whether this approach will significantly improve outcomes remains to be proven

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ACR Meeting Abstracts - https://acrabstracts.org/abstract/tightening-up-musculoskeletal-ultrasound-could-further-individualise-treatment-decisions-in-early-rheumatoid-arthritis-patients-treated-by-a-step-up-dmard-escalation-regimen/