Abstract
Objectives. To identify predictors for Simplified Disease Activity Index (SDAI) remission in patients with established rheumatoid arthritis (RA) under 12 months of anti-TNF therapy combined with synthetic disease modyfing antirheumatic drugs (sDMARD). Methods. We performed a prospective observational study in 90 RA patients with a high active disease refractory to sDMARDs, starting anti-TNFs. Patients were assessed every 3 months based on a well-defined protocol, including individual parameters (clinical, inflammatory) and composite tools (simplified disease activity index SDAI, functional index HAQ-DI); total and IgA-isotype rheumatoid factor (RF) as well as anti-citrullinated peptide antibodies (ACPAs) were measured at baseline, 6 and 12 months. Therapeutic response was evaluated according to EULAR criteria. The primary endpoint was SDAI remission (≤ 3.3) at 12 months of treatment. Univariate and multivariate logistic regression analysis (Forward LR method) were used to assess the manner and intensity in which several parameters (demographics, disease-related, labs and medication) power SDAI remission. Results. SDAI remission was reported in 39.7% cases. We identified nine relevant predictors for SDAI remission at 12 months of therapy by univariate analysis, including: age ≤ 50 years, disease onset ≤ 5 years, RA stages I and II, functional capacity stages I and II, HAQ-DI ≤ 2, concomitent sDMARD, baseline CRP ≤ 20 mg/l, IgA-RF ≤ 20 IU/ml and ACPAs ≤ 40 IU/ml. A mathematical model was further generated, based only on six out of nine parameters: age, disease stage, functional capacity, concomitent sDMARDs, CRP and ACPA. This model expresses a solid approximation for the analysed casess (the Hosmer-Lemeshow test λ² = 0.931, p = 0.920 ≥ 0.05, Cox and Snell R2 0.399). Finally, three significant factors were recognized (age under 50, disease stages I and II, ACPA levels ≤ 40 IU/ml), predicting SDAI remission with an overall constant precision of 83.3%. However, no significant impact on SDAI remission prediction was reported when adding other parameters to the above mentioned model. Conclusion. SDAI remission can be predicted in established RA patients using three major predictors, including age ≤ 50 years, disease stages I and II and baseline ACPA levels ≤ 40 IU/ml.
Highlights
Rheumatoid arthritis (RA) is a complex, multifactorial and heterogeneous disease with significant interpatient variation in symptoms, disease course and therapeutic response [1].Recent advances in understanding the pathologic pathways of RA as well as the availability of emerging newer biological drugs and “treat-to-target” paradigm have redefined the clinical, functional and radiological outcomes of the disease, remission becoming an increasingly attainable goal [2]
74.4% patients were classified as RA stages III and IV, 72.2% had rheumatoid factor (RF) positivity and 60% anti-citrullinated peptide antibodies (ACPAs) positivity; average Simplified Disease Activity Index (SDAI) was 51.38 ± 5.42 and Health Assessment Questionnaire Disability Index (HAQ-DI) was 2.02 ± 0.33 (Table 1)
During the first 12 months of treatment, 50 patients (56.8%) achieved low disease activity, while 35 patients (39.7%) were in remission according to SDAI criteria
Summary
Rheumatoid arthritis (RA) is a complex, multifactorial and heterogeneous disease with significant interpatient variation in symptoms, disease course and therapeutic response [1].Recent advances in understanding the pathologic pathways of RA as well as the availability of emerging newer biological drugs and “treat-to-target” paradigm have redefined the clinical, functional and radiological outcomes of the disease, remission becoming an increasingly attainable goal [2]. Various definitions of RA remission have been developed and used over the last years, at least three of them being still employed: Disease Activity Score (DAS)-28 ≤ 2.6, Simplified Disease Activity Index (SDAI) ≤ 3.3 and Clinical Disease Activity Index (CDAI) ≤ 2.8 score [4,5]. League Against Rheumatism (EULAR), together with the Outcome Measures in Rheumatology Initiative (OMERACT) jointly created a new definition of RA remission [6] – the ACR/EULAR provisional definition of RA remission – intended to be used in clinical trials. SDAI adds the scores from five outcome measures including tender and swollen joint count, patient and physician global assessment of disease and C-reactive protein (CRP). Three cut-off values are currently recognized for SDAI, 3.3 for remission, 11 for low disease activity (LDA), 26 for moderate disease activity (MDA), and more than 26 for high disease activity [7,8]
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