Background/Purpose: Although clinical remission is an agreeable goal of treatment in rheumatoid arthritis (RA), the definition is still controversial. Indeed, progressive structural damage is often found even after achieving DAS28-based remission, suggesting the criteria are not satisfactory for true remission. There is accumulating evidence that ultrasonography (US) is helpful for judgment of the disease remission. Here we investigated whether US is useful for predicting Boolean remission in RA patients who had been satisfied with DAS28-based remission criteria.

Methods: Twenty-seven RA patients who had been in DAS28-based clinical remission (DAS28-ESR < 2.6 or DAS28-CRP < 2.3) for more than 2 months were recruited and monitored for 2 years. Patients who had clinical flare-up were excluded, and the remaining patients were divided based on Boolean remission criteria at 2 years. Bilateral wrists and all of MCPs and PIPs were examined by Gray scale (GS) and power Doppler (PD) US at the entry. GS and PD signals were scored in each joint from 0 to 3, respectively. Total GS score and total PD score were calculated by summing up the score of individual joints. Hand X-ray was evaluated by van der Heijde-modified total Sharp score (mTSS) at the entry and end of study.

 Results: Five patients dropped out of the study due to clinical flare-up, while DAS28 remission had been maintained for 2 years in 22 patients, including 16 patients (73%) who met Boolean remission criteria at the end of study. Both total GS score and total PD score at baseline were significantly lower in Boolean remission group than non-remission group (Table). There was no significant difference in other baseline parameters, including duration of disease, duration of remission, mTSS, and disease activity composite parameters between two groups (Table). However, the increase of patient’s global visual analogue scale (gVAS) and mTSS were significantly smaller during 2 year study period in Boolean remission group than non-remission group (-4.69 ± 10.3 vs 13.2 ± 20.3, p = 0.023, and 0.31 ± 2.36 vs 3.67 ± 3.35, p = 0.047, respectively). In US findings at the entry, total GS score, but not total PD score, was associated with clinical stage, mTSS at baseline, and swollen joint count, tender joint count and gVAS at 2 years. Furthermore, Boolean remission was achieved in all of the 11 patients having total GS score 7 or less at the entry, whereas 6 (55%) of the other 11 patients failed to reach Boolean remission. On the other hand, progression of mTSS was rather associated with high total PD score, but not with total GS score, at the entry.

Conclusion: This study shows that none or low grade of GS and PD findings in US are associated with the achievement of Boolean remission in near future and that GS findings are implicated in exacerbation of clinical parameters composing Boolean remission criteria. Thus, US is essential for assessment and prediction of “true remission” of RA.