Abstract
Objective. To identify predictors for Simplified Disease Activity Index (SDAI) remission in established rheumatoid arthritis (RA) and to develop a predictive score for remission. Methods. Prospective 12-month observational study in ninety active RA receiving their first TNF-α inhibitor. Standard assessments consisted of disease activity scores (DAS28-ESR, SDAI) and immune parameters (total rheumatoid factor, RF; IGA-RF; anti-cyclic citrullinated peptide antibodies, ACPA). The primary outcome measure was SDAI remission (≤ 3.3) at 12 months. Univariate and multivariate logistic regression models were used to estimate association between baseline variables and SDAI remission. Results. 39.7% RA achieved remission, while 56.8% low disease activity. Significant association between SDAI remission and RA-onset before 50 (p = 0.000), history <5 years (p = 0.000), stage (p = 0.000), class I and II Steinbroker functional status (p = 0.022), HAQ-DI≤2 (p = 0.034), CRP ≤ 20mg/l (p = 0.041), IgA-RF ≤ 20 IU/ml (p = 0.002), ACPA ≤ 40 IU/ml (p = 0.047), concomitant DMARDs (p = 0.003) were identified. Four parameters independently predicted 12-month remission (age at onset under 50, RA duration <5 years, ACPA≤40 IU/ml, IgA-RF ≤ 20 IU/ml) as demonstrated by multivariate logistic regression (p<0.05), making correct prediction in 84.4% patients. Furthermore, the remission score correctly classified 90.6% RA, while the transformed simplified version up to 89.4% cases. Gender, clinical parameters and ESR were not predictors for treatment response (p > 0.05). Conclusion. SDAI remission can be predicted in established RA using a score based on age at onset, disease duration, titers of ACPA and RF isotype A. Such a simplified score may help clinicians to manage remission in RA patients according to the current treatment guidelines.
Highlights
Predictors All variables were independently analyzed by univariate logistic regression; only nine parameters were statistically significant and used further as predictors for remission: age at onset, Rheumatoid arthritis (RA) duration and stage, functional class and HAQ-DI, C-reactive protein (CRP), IgA-rheumatoid factor (RF), anticyclic citrullinated peptide antibodies (ACPA), and concomitant Disease Modifying Anti-Rheumatic Drugs (DMARDs)
Statistical analysis showed significant association between Simplified Disease Activity Index (SDAI) remission and onset before 50 years (OR: 5.25, 95% confidential interval (CI) 2.27-12.14; p=0.000), RA duration under 5 years (OR:5.53, 95% CI 2.4012.75; p=0.000), first and second RA stage (OR:4.22, 95% CI 1.99-8.94; p=0.000), functional status as reflected by Steinbroker class I and II and HAQ-DI ≤2 (OR:2.67, 95% CI 1.07-6.68; p=0.022; odds ration (OR):2.39, 95% CI 1.02-5.60; p=0.034, respectively), CRP ≤20 mg/l (OR:1.75, 95% CI 0.81-3.73; p=0.041), IgARF ≤20 IU/ml (OR:5.76, 95% CI 1.43-23.23; p=0.002), ACPA ≤40 IU/ml (OR:1.99, 95% CI 0.954.17; p=0.047) and concomitant DMARDs (OR:5.50, 95% CI 1.36-22.13; p=0.003)
Multivariate logistic regression demonstrated that only age under 50 at onset, symptoms duration up to 5 years, baseline ACPA ≤40 IU/ ml and IgA-RF ≤ 20 IU/ml remained independently associated with SDAI remission at 12 months (Table 2), making correct prediction in 84.4% cases (Hosmer and Lemeshow test fitting λ2 = 3.695, p = 0.718 and Cox and Snell R2 = 0.432)
Summary
Rheumatoid arthritis (RA) is a chronic systemic inflammatory disease of a still unknown etiology, but a complex and dynamic pathophysiology, hypothesized to develop in genetically susceptible host [1]. We performed a prospective study aiming to identify predictors for SDAI remission in patients with established RA treated with TNF inhibitors and to develop a prediction score for remission. Ninety consecutive patients fulfilling the 1987 ACR classification criteria for RA, with established severe active disease (DAS28 ≥ 5.1, SDAI ≥ 26) requiring biologics were enrolled in a prospective observational 12-months study. Standard assessments consisted of 28 joint count, patient reported outcomes, laboratory specimens for CRP, erythrocyte sedimentation rate (ESR), total rheumatoid factor (RF) and IgA-RF isotype, anticyclic citrullinated peptide antibodies (ACPA), as well as disease activity scores (DA28-ESR, SDAI). We created several models based on different (demographic, clinical, biological) variables aiming to investigate their influence on disease outcome (SDAI remission) after 12 months of biological therapy. All statistical analysis was carried out with SPSS16, with „p“ < 0.05
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