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Clinically important changes in individual and composite measures of rheumatoid arthritis activity: thresholds
Michael M Ward1, Lori C Guthrie1, Maria I Alba1
1Intramural Research Program, National Institute of Arthritis and Musculoskeletal and Skin Diseases, National Institutes of Health, Bethesda, Maryland, USA.
Objective:
Thresholds of minimal clinically important improvement (MCII) are needed to plan and interpret clinical trials. We estimated MCIIs for the rheumatoid arthritis (RA) activity measures of patient global assessment, pain score, Health Assessment Questionnaire Disability Index (HAQ), Disease Activity Score-28 (DAS28), Simplified Disease Activity Index (SDAI), and Clinical Disease Activity Index (CDAI).
Methods:
In this prospective longitudinal study, we studied 250 patients who had active RA. Disease activity measures were collected before and either 1 month (for patients treated with prednisone) or 4 months (for patients treated with disease modifying medications or biologics) after treatment escalation. Patient judgments of improvement in arthritis status were related to prospectively assessed changes in the measures. MCIIs were changes that had a specificity of 0.80 for improvement based on receiver operating characteristic curve analysis. We used bootstrapping to provide estimates with predictive validity.
Results:
At baseline, the mean (±SD) DAS28-ESR (erythrocyte sedimentation rate) was 6.16±1.2 and mean SDAI was 38.6±14.8. Improvement in overall arthritis status was reported by 167 patients (66.8%). Patients were consistent in their ratings of improvement versus no change or worsening, with receiver operating characteristic curve areas ≥0.74. MCIIs with a specificity for improvement of 0.80 were: patient global assessment -18, pain score -20, HAQ -0.375, DAS28-ESR -1.2, DAS28-CRP (C-reactive protein) -1.0, SDAI -13, and CDAI -12.
Conclusions:
MCIIs for individual core set measures were larger than previous estimates. Reporting the proportion of patients who meet these MCII thresholds can improve the interpretation of clinical trials in RA.
Insights
New thresholds for minimal clinically important improvement (MCII) in rheumatoid arthritis (RA) were established. These MCIIs for key RA measures can enhance clinical trial interpretation and patient outcome assessment.
Area of Science:
- Rheumatology
- Clinical Trial Design
- Biostatistics
Background:
- Minimal clinically important improvement (MCII) thresholds are crucial for interpreting clinical trial outcomes in rheumatoid arthritis (RA).
- Previous MCII estimates may not accurately reflect meaningful patient improvement in RA activity.
- Standardized MCII values are needed for consistent clinical trial planning and analysis.
Purpose of the Study:
- To estimate MCII thresholds for core RA disease activity measures.
- To provide reliable benchmarks for assessing patient-reported and clinician-assessed RA status.
- To improve the interpretation of treatment effects in RA clinical trials.
Main Methods:
- Prospective longitudinal study of 250 patients with active RA.
- Collection of RA activity measures (e.g., DAS28, HAQ, SDAI) at baseline and post-treatment escalation.
- Receiver operating characteristic (ROC) curve analysis to determine MCIIs with 80% specificity for improvement, using patient global assessment as the reference.
Main Results:
- MCII estimates were determined for patient global assessment, pain, HAQ, DAS28 (ESR and CRP), SDAI, and CDAI.
- Established MCII values include: DAS28-ESR -1.2, DAS28-CRP -1.0, HAQ -0.375, SDAI -13, CDAI -12.
- These MCIIs were generally larger than previously reported estimates.
Conclusions:
- The derived MCIIs for RA core set measures offer improved benchmarks for clinical trials.
- Utilizing these MCII thresholds can lead to more accurate interpretation of patient improvements in RA.
- Reporting the proportion of patients achieving these MCIIs will enhance clinical trial reporting standards.
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