Background Current clinical guidelines recommend testing for anti-citrullinated protein antibodies (ACPA) at the time of RA diagnosis.1 However, there is a lack of information about the frequency of ACPA testing at RA diagnosis or thereafter.
Objectives To describe the frequency of ACPA testing over time and to investigate the potential differences in demographics, co-morbidities and hospitalizations between patients who received ACPA tests versus those who did not.
Methods Data from the three following US commercial healthcare claims databases were analysed: IMS PharMetrics Plus (database A), Optum Clinformatics Data Mart (database B) and Optum Clinformatics Data Mart Medicare (database C). Patients with two diagnosis codes for RA from 1 January 2007 to 31 December 2014, treatment with a DMARD, and continuous enrolment for at least 12 months before and 6 months after the index date were included. ACPA and RF testing claims identified by current procedural terminology codes were included in the analysis. ACPA testing rates were evaluated as number of patients with tests divided by total number of patients with and without tests. Multinomial logistic regression was used to evaluate baseline covariates associated with single ACPA test before the index date, single ACPA test after the index date and multiple ACPA tests.
Results A total number of 67,674 patients newly diagnosed with RA in database A (age 18–64 years), 14,767 in database B (age 18–64 years) and 10,225 in database C (age ≥65 years) met the study inclusion criteria. The overall ACPA testing rate (95% CI) was 70.6% (70.3, 70.9) in database A, 72.2% (71.5, 72.9) in database B and 63.5% (62.5, 64.4) in database C. The ACPA testing rates increased from 2007 to 2014 for all three databases (Figure). The corresponding RF testing rates were 75.4% (75.1, 75.7), 85.1% (84.5, 85.6) and 77.8% (77.0, 78.6), respectively. Patients tested and not tested had similar characteristics, with a standardized difference of >0.10 in only a few co-morbidities. The odds ratio (OR) for pre-diagnosis testing for each year increase from 2007 to 2014 was 1.26 (95% CI: 1.25, 1.28) in database A, 1.19 (1.17, 1.22) in database B and 1.27 (1.23, 1.31) in database C. Women were more likely to have multiple tests in database A (OR: 1.15; 95% CI: 1.08, 1.21) and in database B (OR: 1.29; 95% CI: 1.14, 1.45), but not in database C (OR: 0.93; 95% CI: 0.80, 1.08). Patients who received ACPA tests, versus those who did not, had a lower rate of 1-year hospitalization; the hazard ratio (95% CI) after adjustment for covariates was 0.76 (0.71, 0.80) in database A, 0.86 (0.75, 0.98) in database B and 0.76 (0.68, 0.85) in database C.
Conclusions The ACPA testing rate, especially pre-diagnosis testing, increased significantly from 2007 to 2014. Women aged 18–64 years were more likely to have multiple tests. A slightly lower rate was seen in RA patients ≥65 years old.
Aletaha D, et al. Ann Rheum Dis 2010;69:1580–8.
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, L. Burns Shareholder of: Bristol-Myers Squibb, Employee of: Bristol-Myers Squibb