Session Information
Session Type: Abstract Submissions (ACR)
Background/Purpose: The DAS-28 is used in clinical decision making and research as an outcome assessment for patients with RA. The tool measures clinical, patient centric and inflammatory components of disease activity. Simplification or improvement of the tool would be important in facilitating its use in real–world settings. The objective of this analysis was to assess the internal consistency of the DAS-28 components and contrast these upon replacing patient global assessment (PtGA) with HAQ-DI in RA patients treated with infliximab or golimumab in a Canadian real-world setting.
Methods: BioTRAC is an ongoing, prospective registry of patients initiating treatment for rheumatoid arthritis (RA), ankylosing spondylitis (AS), or psoriatic arthritis (PsA) with infliximab or golimumab as first biologics or after having been treated with a biologic for less than six months. Patients with RA treated with infliximab or golimumab who were enrolled between January 2002 and June 2012 and had a maximum of 60 months of follow-up were included in this analysis.
Results: A total of 510 patients evaluated over 3,817 visits were included in this analysis. Mean follow up was approximately 20 months. The overall correlation between TJC and SJC was high (r = 0.746), whereas the correlations of ESR with TJC (r = 0.187) and SJC (r = 0.212) were poor. The correlation between patient assessment of disease activity (PtGA) was poor with ESR (r = 0.190) and modest for TJC (r = 0.519) and SJC (r = 0.487). Internal consistency was low [Cronbach’s alpha (CA) = 0.482) and Intra-Class Correlation Coefficient (ICC) = 0.205]. All item-item correlations, ICC and CA deteriorated with time over the 60-month follow up period. The correlations of TJC (r = 0.454) and SJC (r = 0.367) with HAQ-DI were lower when compared to those with PtGA while the correlation of ESR (r = 0.260) was higher with HAQ-DI. Replacement of PtGA with HAQ-DI would result in lower internal consistency (CA = 0.337) suggesting modest improvement in validity.
The slopes measuring rate of change over time for the DAS-28 items showed acceptable internal consistency (ICC = 0.638). Item-item correlations were low for the ESR-slope with PtGA-Slope (r = 0.262), TJC-Slope (r = 0.240) and SJC-Slope (r = 0.300); PtGA-slope had moderate correlation with SJC-Slope (r = 0.512) and TJC-Slope (r = 0.570). When compared to PtGA, HAQ-DI-Slope had comparable correlations with the slopes of the DAS-28 components
Conclusion: There is poor cross sectional and longitudinal correlation between the DAS-28 components indicating that they are measuring related but discriminating concepts of disease activity. The exception being SJC and TJC and therefore exclusion of one of these measures may be considered. Replacement of PtGA with HAQ within the DAS-28 would not provide any significant statistical benefits however it could offer practical benefits (i.e. reduce measurement workload) without loss of the validity of DAS-28.
Disclosure:
A. Chow,
JNJ, Amgen, Pfizer, Abbvie, UCB, Eli Lilly, Celgene, Takeda, Astra Zeneca, BMS, Roche,
5;
J. C. Thorne,
Amgen,
5,
Pfizer Inc,
5,
Abbott Laboratories,
5,
Bristol-Myers Squibb,
5,
Centocor, Inc.,
5,
Merck Pharmaceuticals,
5,
Roche Pharmaceuticals,
5,
UCB,
5;
R. Arendse,
None;
D. E. Sholter,
None;
D. Choquette,
None;
I. Fortin,
None;
B. Haraoui,
Amgen,
5,
Abbott Laboratories,
5,
Bristol-Myers Squibb,
5,
Merck Pharmaceuticals,
5,
Pfizer Inc,
5,
Roche Pharmaceuticals,
5,
UCB,
5;
E. Rampakakis,
None;
J. S. Sampalis,
None;
F. Nantel,
None;
A. J. Lehman,
Janssen Canada,
3;
M. Shawi,
Janssen Canada,
3;
S. M. Otawa,
Janssen Canada,
3.
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ACR Meeting Abstracts - https://acrabstracts.org/abstract/what-is-the-internal-consistency-of-the-disease-activity-score-das-28-in-rheumatoid-arthritis-patients-treated-in-a-real-world-setting/