Background Due to the introduction of biological agents that inhibit the pro-inflammatory cytokines, IL-6 and TNF-α, remission has become a goal in the treatment of RA. Rheumatoid factor (RF) and the Health Assessment Questionnaire (HAQ) have both been investigated as indicators of poor treatment response and poor prognosis. PCT is used for the diagnosis of infections. Although it has been reported that PCT is expressed from peripheral blood mononuclear cells induced by a pro inflammatory cytokine and that it is expressed in the tissues of many human organs, it has rarely been investigated in relation to noninfectious complication of RA.

Objectives To investigate whether the levels of PCT and other RA diagnostic and disease activity indicators before the start of TCZ treatment (pre-TCZ) can be used to predict remission at 24 weeks after the start of TCZ treatment (Week 24).

Methods Of the 216 patients who started TCZ treatment until September 2012 at our center, those who were observed at Week 24 were analyzed in this study. PCT (n=30), erythrocyte sedimentation rate (ESR) (n=164), RF (n=154), matrix metalloproteinase (MMP)-3 (n=166) and modified HAQ (mHAQ) (n=123) were found pre-TCZ, and the Disease Activity Score (DAS)28-ESR was found as a measure of disease activity. The patients were divided into 2 groups, based on DAS28-ESR remission at TCZ Week 24: the remission (R) group (DAS28-ESR<2.6) and the non-remission (NR) group. For each variable for which there was a significant difference between the R group and the NR group, receiver operating characteristic (ROC) analysis was performed and cut-off values (COV) were found. For each of those variables, 2 groups were formed by dividing the patients at the COV: the under COV (U)group and the over CV (O) group, andthe Week 24 remission rate in each group was found.

Results The variables witha significant difference between the R group and the NR group were PCT (p=0.013), MMP-3 (p=0.028), RF (p<0.0001), mHAQ (p<0.0001), and ESR (p<0.0001). The COVs were 0.026 ng/ml for PCT, 86 mg/dl for MMP-3, 94U/ml for RF, 0.5 for mHAQ, and 29 mm/hr for ESR. For each variable, the remission rate in the U group (PCT: 91.7%, MMP-3: 68.2%, RF: 63.0%, mHAQ: 78.5%, and ESR: 62.9%) was significantly higher than in the O group. The pre-TCZ AS28-ESR was significantly lower in the U groups for MMP-3, RF, mHAQ, and ESR, and a correlation with DAS28-ESR was seen for each variable. For PCT, on the other hand, there was no inter-group difference between the Ugroup andO group pre-TCZ DAS28-ESRs and no correlation with pre-TCZ DAS28-ESR, but there was a Spearman rank correlation with the Week 24 DAS28-ESR (r=0.49, p<0.01).

Conclusions The results of this study suggest that the pre-TCZ PCT level may be a useful predictor of remission at Week 24 of TCZ treatment, and also that, unlike theother indicators, it is not affected by the pre-TCZ disease activity level.

Disclosure of Interest None Declared