ObjectiveTo investigate whether antidrug antibodies and/or drug non‐trough levels predict the long‐term treatment response in a large cohort of patients with rheumatoid arthritis (RA) treated with adalimumab or etanercept and to identify factors influencing antidrug antibody and drug levels to optimize future treatment decisions.MethodsA total of 331 patients from an observational prospective cohort were selected (160 patients treated with adalimumab and 171 treated with etanercept). Antidrug antibody levels were measured by radioimmunoassay, and drug levels were measured by enzyme‐linked immunosorbent assay in 835 serial serum samples obtained 3, 6, and 12 months after initiation of therapy. The association between antidrug antibodies and drug non‐trough levels and the treatment response (change in the Disease Activity Score in 28 joints) was evaluated.ResultsAmong patients who completed 12 months of followup, antidrug antibodies were detected in 24.8% of those receiving adalimumab (31 of 125) and in none of those receiving etanercept. At 3 months, antidrug antibody formation and low adalimumab levels were significant predictors of no response according to the European League Against Rheumatism (EULAR) criteria at 12 months (area under the receiver operating characteristic curve 0.71 [95% confidence interval (95% CI) 0.57, 0.85]). Antidrug antibody–positive patients received lower median dosages of methotrexate compared with antidrug antibody–negative patients (15 mg/week versus 20 mg/week; P = 0.01) and had a longer disease duration (14.0 versus 7.7 years; P = 0.03). The adalimumab level was the best predictor of change in the DAS28 at 12 months, after adjustment for confounders (regression coefficient 0.060 [95% CI 0.015, 0.10], P = 0.009). Etanercept levels were associated with the EULAR response at 12 months (regression coefficient 0.088 [95% CI 0.019, 0.16], P = 0.012); however, this difference was not significant after adjustment. A body mass index of ≥30 kg/m2 and poor adherence were associated with lower drug levels.ConclusionPharmacologic testing in anti–tumor necrosis factor–treated patients is clinically useful even in the absence of trough levels. At 3 months, antidrug antibodies and low adalimumab levels are significant predictors of no response according to the EULAR criteria at 12 months.

Objective. An elevated acute-phase response is associated with increased radiologic damage in rheumatoid arthritis (RA), but development of damage in previously normal joints ("new joint involvement") has not previously been investigated. This study was undertaken to investigate the hypothesis that when there is suppression of disease activity as judged by the C-reactive protein level, new joint involvement is reduced to a greater extent than is progression in already damaged joints ("damaged joint progression").Methods. Three hundred fifty-nine patients with active RA were studied as part of a 5-year randomized, prospective, open-label study of disease-modifying antirheumatic drug therapy. Time-averaged CRP was calculated from samples obtained every 6 months, and patients were divided into groups with CRP values of < < <6, 6-< < <12, 12-< < <25, and > > >25 mg/liter. Radiographs of the hands and feet were scored by the Larsen method; a damaged joint was defined as one with a score of > > >2.Results. The rank correlation between timeintegrated CRP and increase in Larsen score was 0.50; the correlation increased to 0.59 for patients entering the study with disease duration of < < <2 years. The percentage of new joint involvement over 5 years varied markedly with time-integrated CRP, from 7.3% in the CRP < < <6 mg/liter group to 39.1% in the CRP > > >25 mg/liter group (5.4-fold increase). The percentage of damaged joint progression increased from 26.1% in the CRP < < <6 mg/liter group to 41.6% in the CRP > > >25 mg/liter group (1.6-fold increase).Conclusion. The results of this study provide further confirmation that high CRP levels over time are associated with greater radiologic progression. Although radiologic progression still occurred in both previously normal and damaged joints despite the presence of normal CRP levels, this consisted of proportionately less new joint involvement compared with damaged joint progression. These findings support the idea that disease-suppressive therapy should be instituted at an early stage in patients with RA, before erosive damage has occurred.

Conclusions:In people with established RA, semi-rigid customised foot orthoses can improve pain and disability scores in comparison to simple insoles. From a cost effectiveness perspective the customised foot orthoses were far more expensive to manufacture, with no significant cost per QALY gain.