Background Current recommendations for rheumatoid arthritis (RA) management emphasize treat-to-target strategies which reduce joint destruction. However, recent studies showed radiographic progression even in remission RA patients and novel predictors were required.
Objectives To evaluate clinical, serological and radiographic indicators in predicting radiographic progression in RA patients achieved therapeutic target.
Methods Patients with active RA (SDAI >11.0) were treated according to recommendations and followed up at 1st, 3rd, 6th, and 12th months. Serum matrix metalloproteinase (MMP) 3 was detected by ELISA and clinical data was collected simultaneously at baseline and each visit. X-ray assessment of hand/wrist was repeated and radiographic progression was defined as the increase of total Sharp score more than 0.5 from baseline to one year. Patients who achieved therapeutic target at 6th month were included in the analysis.
Results (1) Fifty-six patients were recruited and fulfilled 1-year follow-up. Forty-two (75%) of them achieved therapeutic target at 6th month. Among the 42 patients, 71% were female, age (median and IQR, similarly hereinafter) was 49 (38–56) years, disease duration was 18 (12–72) months, SDAI at baseline was 26.5 (14.5–37.4), and 62% were treated with csDMARDs while 38% were treated with bDMARD. Eleven (26%) of them had radiographic progression at 12th month.
(2) Among the clinical indicators, serum MMP-3 and Sharp score at baseline, multivariable stepwise logistic regression showed that high level of baseline Sharp score was a significant predictor of 1-year radiologic progression (OR=1.045, 95%CI: 1.001–1.091,P=0.045). ROC curve analysis showed that the tradeoff value of baseline Sharp score for predicting 1-year radiographic progression was 15 with positive predictive value (PPV) 58% and negative predictive value (NPV) 87% (AUC=0.740, 95%CI: 0.562–0.919, P=0.019, Fig 1B).
(3) Serum MMP-3 decreased to normal at 6th month in half non-progressive patients but continually elevated throughout 12 months in progressive patients, while SDAI showed similar decreasing between non-progressive and progressive groups (all P>0.05, Fig. 1A). Univariate logistic regression analysis showed that elevated serum MMP-3 at 6th month was a significant predictor for 1-year radiographic progression in RA patients (OR=1.006, 95%CI: 1.001–1.011, P=0.010). ROC curve analysis showed that the tradeoff value of serum MMP-3 at 6th month for predicting 1-year radiographic progression was 161 ng/ml with PPV 67% and NPV 90% at 6th month (AUC=0.789, 95%CI: F0.612–0.965, P=0.005, Fig. 1B)
(4) According to the tradeoff value of Sharp score and serum MMP-3 above, ROC curve analysis showed that the PPV and NPV of combination of baseline Sharp score and serum MMP-3 at 6th month for predicting 1-year radiographic progression was 61% and 100% (AUC=0.887, 95%CI: F0.789–0.985, P<0.001, Fig. 1B).
Conclusions Our results implied that combination of baseline Sharp score and dynamic serum MMP-3 might be helpful in predicting radiographic progression in RA patients achieved therapeutic target.
Acknowledgements This work was supported by National Natural Science Foundation of China (81471597) and Specialized Research Fund for the Doctoral Program of Higher Education (20130171110075).
Disclosure of Interest None declared