Objectives Remission in systemic lupus erythematosus (SLE) is defined through a combination of ‘clinical SLE Disease Activity Index (cSLEDAI)=0’, ‘physician's global assessment (PGA) <0.5’ and ‘prednisone (PDN) ≤5 mg/day’. We investigated the performance of these items, alone or in combination, in defining remission and in predicting SLICC/ACR Damage Index.
Methods We tested seven potential definitions of remission in SLE patients followed-up for ≥5 years: PDN ≤5 mg/day; PGA <0.5; cSLEDAI=0; PGA <0.5 plus PDN ≤5 mg/day; cSLEDAI=0 plus PGA <0.5; cSLEDAI=0 plus PDN ≤5 mg/day; cSLEDAI=0 plus PDN ≤5 mg/day plus PGA <0.5. The effect of these definitions on damage was evaluated by Poisson regression analysis; the best performance was identified as the lowest Akaike and Bayesian information criterion (AIC and BIC). Positive and negative predictive values in identifying no damage increase were calculated.
Results We included 646 patients (mean±SD disease duration 9.2±6.9 years). At multivariate analysis, ≥2 consecutive year remission according to all definitions protected against damage (OR, 95% CI: PGA <0.5 0.631, 0.444 to 0.896; cSLEDAI=0 0.531, 0.371 to 0.759; PGA <0.5 plus PDN ≤5 mg/day 0.554, 0.381 to 0.805; cSLEDAI=0 plus PGA <0.5 0.574, 0.400 to 0.826; cSLEDAI=0 plus PDN ≤5 mg/day 0.543, 0.376 to 0.785; cSLEDAI=0 plus PDN ≤5 mg/day plus PGA <0.5 0.532, 0.363 to 0.781, p<0.01 for all), except PDN ≤5 mg/day, which required four consecutive years (OR 0.534, 95% CI 0.325 to 0.877, p=0.013). Positive and negative predictive values were similar; however, cSLEDAI=0 showed the best performance (AIC 1082.90, BIC 1109.72, p<0.0001). Adding PGA <0.5 and/or PDN ≤5 mg/day to cSLEDAI=0 decreased remission duration (−1.8 and −1.5 year/patient, respectively) without increasing cSLEDAI=0 performance in predicting damage accrual.
Conclusions cSLEDAI=0 is the most attainable definition of remission, while displaying the best performance in predicting damage progression in the short-to-mid-term follow-up.
- disease activity
- systemic lupus erythematosus
- outcomes research
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Handling editor Josef S Smolen
Contributors FS contributed to the conception and design of the work, the follow-up of patients, acquisition, analysis and interpretation of data, and mostly drafted the work; MZ and MGa followed up patients, contributed to the acquisition of data and helped in drafting and revising the paper; FCo, AA, GM, MGo, AT, MM and LI followed up patients and revised the manuscript; FCe, DPEM, GF, FD, VS and AB followed up patients and contributed to the acquisition of data; ACF contributed to and revised the analysis of data; AD designed the work, interpreted the data and revised the manuscript for important intellectual content. All the authors approved the final version of the manuscript and gave their agreement to be accountable for all aspects of the work in ensuring that questions related to the accuracy or integrity of any part of the work are appropriately investigated and resolved.
Funding The authors have not declared a specific grant for this research from any funding agency in the public, commercial or not-for-profit sectors.
Competing interests None declared.
Patient and public involvement Patients and/or the public were not involved in the design, or conduct, or reporting, or dissemination plans of this research.
Patient consent for publication Not required.
Ethics approval The study was approved by the Ethics committee of Padova University (3806/AO16).
Provenance and peer review Not commissioned; externally peer reviewed.
Data availability statement All data relevant to the study are included in the article or uploaded as online supplementary information. Data are available on reasonable request from Prof A Doria (ORCID 0000-0003-0548-4983). Reuse of data is not permitted by a third party without authorisation.
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