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Abstract
Background Testing for anti-citrullinated peptide antibodies (ACPA) has become standard in RA diagnosis in clinical practice, partly due to improved assay specificity compared with detection techniques for antibodies against RF.1 ACPA concentration, beyond ACPA positivity, is indicative of more aggressive radiographic progression.2 However, there is limited information on the association between changes in ACPA levels in clinical practice and resource use measures.
Objectives To evaluate the association of changes in ACPA levels with resource use (durable medical equipment [DME] use/hospitalizations) in clinical practice.
Methods Patients enrolled in the Brigham and Women's Hospital Rheumatoid Arthritis Sequential Study (BRASS) Registry, established in 2003, were analysed. BRASS primarily comprises patients with established RA who were evaluated semi-annually for multiple, clinical patient-reported outcomes and resource utilization parameters. The current analysis is based on patients enrolled in the BRASS registry who had ACPA values at baseline and at follow-up visits. ACPA levels were measured by well-documented and validated ELISAs from Inova Diagnostics (San Diego, CA), until its discontinuation in 2011, and Euro-Diagnostica (distributed by IBL-America, Minneapolis, MN) thereafter. Annual mean ACPA change from baseline (CFB) to 12 months was calculated and categorized as decrease (1+ unit decrease), no change (>–1 to <1 unit change) or increase (1+ unit increase). DME use of canes, wheelchairs, walkers and commodes as well as hospitalizations were assessed every 6 months. Multivariate regression analyses controlling for baseline covariates were conducted to evaluate associations between ACPA CFB and resource use measures defined by DME and hospitalizations.
Results A total of 840 patients (64%) in BRASS had ACPA values at baseline and follow-up and were included in the current analysis. A decrease in ACPA levels was observed in 42.6% (n=358) of patients, 18.1% (n=152) had no change and 39.3% (n=330) had an increase. There were no significant differences in baseline characteristics between the three groups, except for BMI; patients with RA with an increase in ACPA levels had significantly lower BMI at baseline. In univariate analyses, the percentages of patients with DME use were 23.8, 30.5 and 29.8% in the groups with a decrease, no change and an increase in ACPA levels, respectively. Similarly, the percentages of patients with hospitalizations were 13.7, 13.9 and 21.3%, respectively. After controlling for baseline covariates, the odds ratio for DME use over 12 months in patients who had an ACPA decrease (vs increase) was 0.60 (95% CI 0.41, 0.89; p=0.011), and the odds ratio for hospitalization was 0.49 (95% CI 0.32, 0.75; p=0.001; Figure).
Conclusions A reduction in ACPA levels was associated with a reduction in DME use and hospitalizations.
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Disclosure of Interest E. Alemao Shareholder of: Bristol-Myers Squibb, Employee of: Bristol-Myers Squibb, Z. Guo Shareholder of: Bristol-Myers Squibb, Employee of: Bristol-Myers Squibb, C. Iannaccone: None declared, M. Frits: None declared, N. Shadick Grant/research support from: Bristol-Myers Squibb, Crescendo Biosciences, Amgen, UCB, Questcor, M. Weinblatt Grant/research support from: Bristol-Myers Squibb, Crescendo Bioscience, UCB, Amgen, Consultant for: Bristol-Myers Squibb, Crescendo Bioscience, UCB, AbbVie, Roche, Janssen, Pfizer, Lilly, Amgen