Background/Purpose: The feet
are often involved in rheumatoid arthritis (RA), but physical examination of
the metatarsophalangeal (MTP) joints to detect arthritis is challenging
especially in case of obesity, oedema and malalignment. Ultrasound has proven
to be more sensitive than physical examination to detect (subclinical)
synovitis in the MTP joints. Our aim was to determine the frequency of
subclinical synovitis in the MTP joints by ultrasound among patients in DAS28
remission or low disease activity, and to assess the evolution of ultrasound
synovitis in the feet and DAS28 over time in newly diagnosed RA patients who
are treated to target.

Methods: A multicentre cohort of newly
diagnosed RA patients (ACR 1987 criteria) was followed prospectively for one
year. Patients were treatment naïve for synthetic DMARDs, biological DMARDs and
glucocorticoids, and symptom duration was less than one year. All patients were
treated to target with regular visits. Demographics, clinical (SJC28, TJC28)
and laboratory (ESR, RF, ACCP) parameters were recorded at each visit.
Ultrasound examination of the dorsal aspect of MTP2-5 joints was performed at
baseline, three months and one year. Images were scored on greyscale (GS;0-3)
and power Doppler (PD;0-3). An ultrasound positive MTP joint was defined by
GS>1 and/or PD>0. Simple descriptive statistics were used and longitudinal
course of DAS28 and number of ultrasound positive MTP joints were plotted for
each patient.

Results: At baseline, 174 patients were
included of whom 159 completed one year follow-up. At baseline, 109 (73%)
patients had at least one ultrasound positive MTP joint. Overall, mean(sd)
DAS28 decreased from 4.9(1.3) at baseline to 2.3(1.2) at one year, while the
number of ultrasound positive MTP joints decreased from median(interquartile
range) 1(0-4) at baseline to 0(0-0) at one year. Discordance in evolution of
DAS28 and ultrasound positive MTP joints over one year was seen in 9 patients
(6%). After one year of follow-up, 98 (62%) patients were in DAS28 remission
(DAS28<2.6) of whom 23 (23%) still had at least one ultrasound positive MTP
joint. Twenty-nine patients had low disease activity (DAS28≤3.2) of whom
7 (24%) had at least one ultrasound positive MTP joint.

Conclusion: Most patients (94%) improved both
in DAS28 score and number of US positive MTP joints during follow-up. However,
23% of the early RA patients in DAS28 remission still had ultrasound synovitis
in at least one MTP joint at one year. Monitoring of MTP joints by ultrasound and
subsequent steering of treatment might be considered to prevent for example
progressive radiological damage.