Suppress the joint destruction in clinical remission patients who have active synovitis of ultrasonographic assessment by increasing the dose of methotrexate

INTERVENTION: We randomly assigned patients who have the positive joint of power Doppler signal by ultrasonography even in clinical remission to increase or stable the dose of MTX and observation . MTX increase group was increased to 16mg, it will continue to increase as much as possible. We randomly assigned patients who have the positive joint of power Doppler signal by ultrasonography even in clinical remission to increase or stable the dose of MTX and observation . MTX increase group was increased to 16mg, it will continue to increase as much as possible. We observe the patients if there is no positive joint power Doppler signal. CONDITION: rheumatoid arthritis PRIMARY OUTCOME: the change of X‐ray from baseline in the van der Heijde‐Sharp score at week 52 SECONDARY OUTCOME: the change of X‐ray from baseline in the van der Heijde‐Sharp score at week 24; the change of power doppler signal from baseline in the van der Heijde‐Sharp score at week 24and 52 INCLUSION CRITERIA: RA patients fulfilling the American Rheumatology Association criteria 1987 and ACR/EULAR classification cliteria 2010. The patients who have stable remission, defined as a 28‐joint disease activity score CRP (DAS28‐CRP) <2.6 for at least 3 months.