Background/Purpose: Anti-citrullinated protein antibodies (ACPA) have emerged as promising serological biomarkers of rapidly progressing RA and are associated with more severe disease and joint damage. ACPA testing has been increasingly used as a routine tool for RA diagnosis. Furthermore, treatment efficacy has been shown to vary by ACPA-positive (+) status.¹ However, little is known about the economic burden of patients with RA who are ACPA+.   

Methods: IMS PharMetrics Plus health insurance claims and electronic medical record (EMR) data from 2010 to 2015 were used to identify patients with incident RA. Patients were ≥18 years of age, had ≥1 inpatient or ≥2 outpatient claims reporting an RA diagnosis code (International Classification of Disease, Ninth Revision, code 714.0), and had an anti-cyclic citrullinated peptide (anti-CCP, a surrogate of ACPA) antibody test within 6 months of diagnosis. Incident patients were defined as those who had no claims with an RA diagnosis code in the 6 months before the first observed RA diagnosis. The primary outcome of interest was RA-related medical expenditure, defined as the sum of payer- and patient-paid amounts for all claims with an RA diagnosis code. Secondary outcomes included healthcare utilization metrics such as treatment with a DMARD and physician visits. Generalized linear regression models were used for each outcome, with ACPA+ status (anti-CCP ≥20 U/mL), age, sex and Charlson co-morbidity index as explanatory variables.    

Results: Of 647,171 patients diagnosed with RA, 89,296 were incident cases meeting inclusion criteria and 47% (n=42,285) had an anti-CCP test. Restricting the sample to 9747 patients with a linked EMR, 859 reported an ACPA test result. Of these, 25% (n=212) were ACPA+ and 26% (n=219) were male. Compared with ACPA-negative (–) patients, adjusted results showed that ACPA+ patients were more likely to use either conventional (71.2 vs 49.6%, p<0.001) or biologic (20.3 vs 11.8%, p<0.001) DMARDs during the first year after diagnosis, and had more physician visits (5.57 vs 3.91 times/year, p<0.001). The annual RA-associated total expenditure was $7940 for ACPA+ and $5243 for ACPA– patients (Δ=$2697, p=0.002; Figure 1). Medical expenditure (i.e. excluding prescription drug costs) was $4380 for ACPA+ and $3427 for ACPA– patients (Δ=$954, p=0.168).

Conclusion: Patients with RA who are ACPA+ have a higher RA-related economic burden than patients who are ACPA–. Providers may consider utilizing the results of anti-CCP testing to inform treatment decisions in this higher-cost population of patients with RA. 1.    Sokolove JS, et al. Ann Rheum Dis 2016;75:709–14.