STR is swollen to tender joint count ratio. The aim of this study was to determine the usefulness of STR in predicting response to treatment with biological agents in patients with RA.
The study included 27 biologically naive patients treated with TNF inhibitors: infliximab (6), etanercept (10), adalimumab (5) and certolizumab (6). STR index was assessed at baseline and after 3 and 9 months (m) . Patients due to the STR value were divided into two groups: group1 with value of STR < 1 and group 2 with value of STR ≥ 1. Group 1 included 18 patients (17 F, 1 M). Group 2 consisted of 9 persons (7 F 2 M).
At the beginning of the observation the average values for the group 1 were: the number of swollen joints (SJ) 6/28 (2-14), the number of tender joints (TJ) 11/28 (5-21), STR 0.46 (0.2-0.9), CRP 27.8 mg/I (1-130.2), DAS28 4.95 (4.03-7.56), disease activity VAS 50 mm (20-75), ESR 35 (8-95). In group 1, the DAS28 improved after 3 months on average - 1.68 (0.08-3.91) and ESR decreased about 16 mm. On the assessment after 9 months of treatment DAS 28 improved on average - 2.89 (0.74-5.17); ESR dropped by 21 mm compared to the baseline. At the beginning of the observation average values for group 2 were: SJ 13/28 (8-19), TJ 19 (4-15), STR 1.48 (1-2.5), CRP 19.27 (7.7-32.1), DAS28 5.75 (5.25-6.47), disease activity - VAS 57 mm (47-66), ESR 25 (14-41). After 3 months of treatment DAS28 reduced on average - 2.52 (1.97-3.71), ESR decreased circa 11 mm. Six patients from group 2 were evaluated after 9 months of treatment. There was observed improvement both in DA528 on average 3.28 (1.86-3.95) and ESR, which dropped by 10 mm. Patients with >1 STR achieved greater improvement in DAS28 after 3 m (p=0.0395) and after 9 months (Ns) compared to patients with STR <1. However, decrease of ESR was higher both after 3 and 9 months in patients with STR <1.
We conclude that the STR may be useful in predicting response to treatment with TNF inhibitors.