Background Arthralgia and arthritis are common features of disease activity in patients with primary Sjögren's syndrome (pSS) with prevalence rates of 45-50% and 15-35%, respectively. Disease Activity Score including 28 joints (DAS-28) has been developed and validated to monitor disease activity in patients with rheumatoid arthritis, but it is also used in other auto-immune diseases. This extrapolation of indications is very relevant in the current scientific debate on comparability of the efficacy of biologicals and biosimilars.
Objectives To evaluate the usefulness of DAS-28ESR in pSS patients treated with rituximab or abatacept.
Methods pSS patients treated with rituximab or abatacept within our previously reported studies1,2 were selected based on DAS-28ESR of ≥3.2 at baseline. Eighteen patients treated with rituximab (1000 mg, days 1 and 15) were evaluated at baseline and at weeks 16, 24, 36, 48 and 60 after treatment. Thirteen patients treated with abatacept infusions (∼10 mg/kg of body weight, days 1, 15 and 29 and every 4 weeks thereafter) were evaluated at baseline and at weeks 4, 12, 24 (on treatment), 36 and 48 weeks (off treatment). All patients fulfilled the revised American-European Consensus Group criteria for pSS and were ACPA antibody negative. Generalized estimating equations were used to analyse DAS-28ESR over time within both treatment groups. P<0.05 was considered statistically significant.
Results At baseline, the median DAS-28ESR score was 3.7 and 4.5 in the rituximab and abatacept treatment studies, respectively. Following rituximab treatment, DAS28ESR decreased significantly up to 48 weeks and returned to baseline values at week 60 (Figure 1A). In abatacept treated patients, DAS-28ESR decreased significantly up to 24 weeks and returned to baseline values at week 36 (Figure 1B). The proportion of patients with any degree of activity (score ≥1) in the articular domain of the EULAR Sjögren's Syndrome Disease Activity Index (ESSDAI) are shown in Figure 1.
Conclusions To our knowledge, this is the first analysis using DAS-28ESR to evaluate the disease activity in patients with pSS. The present results indicate that DAS-28ESR can be used to evaluate biologic therapies in trials with pSS patients. DAS-28ESR has a good sensitivity to change and is valuable to monitor disease activity in pSS. Moreover, DAS-28ESR score has comparable course over time with the articular domain of the ESSDAI score. Summarized, DAS-28ESR is useful not only in patients with RA, but also in patients with pSS. This is of particular relevance for the extrapolation of indications and comparison of biosimilars in the treatment of auto-immune diseases.
Responsiveness of disease activity indices ESSPRI and ESSDAI in patients with primary Sjögren's syndrome treated with rituximab. Meiners PM, Arends S, Brouwer E, et al. Ann Rheum Dis. 2012 Aug;71(8):1297-302.
Abatacept treatment reduces disease activity in early primary Sjögren's syndrome (open-label proof of concept ASAP study). Meiners PM, Vissink A, Kroese FGM, et al. Ann Rheum Dis. 2014 Jul;73(7):1393-6.
Disclosure of Interest None declared