Is the frequent sonographic anechoic area distally in metacarpophalangeal joints a sign of arthritis?

In clinical practice, ultrasonography (US) often reveals, in the dorsal scan, a small anechoic area distally in both inflamed and clinically non-inflamed metacarpophalangeal joints. This "distal anechogenicity in the metacarpophalangeal joint" (DAEM) might thus be scored false positively as arthritis. We aimed to investigate whether the DAEM is a sign of arthritis. We evaluated the prevalence of DAEMs in 24 non-arthritic subjects. We then compared the dimensions of the DAEM in 10 non-arthritic subjects with a DAEM and 7 consecutive rheumatoid arthritis (RA) outpatients, using 2-D and 3-D ultrasound. Furthermore, we dissected two fresh-frozen postmortem hand specimens after US. A DAEM was observed in the metacarpophalangeal 2 (MCP2) joints of 54% of the 24 non-selected non-arthritic individuals; in none of those did the joint exhibit a power Doppler signal. A DAEM was observed in 86% of the 7 RA patients. Dimensions of DAEMs did not statistically significantly differ between these groups. At 3-D imaging and dissection, the DAEM was found to be an extension of the metacarpophalangeal joint capsule. In conclusion, DAEMs occur frequently and are not a sign of arthritis, but are distal joint recesses. This should be taken into account when using current sensitive ultrasonographic scoring systems grading arthritis.

Diagnostic performance of the ACR/EULAR 2010 criteria for rheumatoid arthritis and two diagnostic algorithms in an early arthritis clinic (REACH).

INTRODUCTION: An ACR/EULAR task force released new criteria to classify rheumatoid arthritis at an early stage. This study evaluates the diagnostic performance of these criteria and algorithms by van der Helm and Visser in REACH. METHODS: Patients with symptoms ≤12 months from REACH were used. Algorithms were tested on discrimination, calibration and diagnostic accuracy of proposed cut-points. Two patient sets were defined to test robustness; undifferentiated arthritis (UA) (n=231) and all patients including those without synovitis (n=513). The outcomes evaluated were methotrexate use and persistent disease at 12 months. RESULTS: In UA patients all algorithms had good areas under the curve 0.79, 95% CI 0.73 to 0.83 for the ACR/EULAR criteria, 0.80, 95% CI 0.74 to 0.87 for van der Helm and 0.83, 95% CI 0.77 to 0.88 for Visser. All calibrated well. Sensitivity and specificity were 0.74 and 0.66 for the ACR/EULAR criteria, 0.1 and 1.0 for van der Helm and 0.59 and 0.93 for Visser. Similar results were found in all patients indicating robustness. CONCLUSION: The ACR/EULAR 2010 criteria showed good diagnostic properties in an early arthritis cohort reflecting daily practice, as did the van der Helm and Visser algorithms. All were robust. To promote uniformity and comparability the ACR/EULAR 2010 criteria should be used in future diagnostic studies.