To evaluate the significance of serum matrix metalloproteinase-3 (MMP-3) and joint ultrasonography in assessing the activity of rheumatoid arthritis (RA) by comparing MMP-3 level and the ultrasonic 7 joints (US7) score in RA patients.
Serum MMP-3 level and US7 score were measured in 133 RA patients by immune turbidity and Doppler ultrasound. Synchronous 53 healthy subjects were recruited as controls. Clinical data were collected. Erythrocyte sedimentation rate (ESR), serum level of anti-cyclic citrullinated peptide (CCP) antibody, health assessment questionnaire (HAQ) and disease activity score 28 (DAS28) were measured. The level of disease activity is interpreted as remission(DAS28<2.6), low(DAS 28≥2.6-<3.2), moderate(DAS 28≥3.2-<5.1), high(DAS28≥5.1). The discriminating validity of MMP-3 and US7 score in disease was evaluated using receiver operating characteristic (ROC) curve analysis with DAS28 as the reference standard.
Compared with that in healthy controls [35.20(25.90, 48.90) μg/L] and remission patients[33.40(22.60, 678.40) μg/L], the MMP-3 level in moderate [105.1(61.70, 172.70) μg/L] and high [363.1(161.50, 475.90) μg/L] groups increased dramatically. US7 score in patients with high disease activity was significantly higher than that in other groups. The level of MMP-3 was significantly correlated with DAS28, HAQ, US7 score, yet did not have correlation with anti-CCP antibody. Serum level of MMP-3 was positively correlated with US7 score(r=0.566, P<0.001). In evaluating the disease activity, US7 score combined with MMP-3 (AUC 0.863 2) was not superior to MMP-3 alone (AUC 0.854 3), but significantly better than single US7 score (AUC 0.764 3, P<0.05).
MMP-3 is an effective and simple index in evaluating RA disease activity. The combination of MMP-3 and US7 score does not further improve the efficacy to evaluate disease activity than MMP-3 alone in patients with RA.