Background/Purpose:

Absent contraindications to conventional DMARD (cDMARD) use, the Veterans Administration (VA) requires a 3-month trial of 2 cDMARDs prior to the use of biologic DMARD (bDMARD), for active rheumatoid arthritis (RA). In this national VA study, we used a time-to-event analysis in cases of newly-identified RA to examine variation between VA Integrated Service Network (VISN) areas in prescriptions following MTX monotherapy.

Methods:

A previously validated, 3-part definition was used to identify patients with RA within the VA Musculoskeletal Disorder (MSD) cohort (N > 5 million, Jan 1, 2000-Dec 31, 2013). The date of the first VA DMARD prescription was used to define both RA diagnosis and RA cohort entry. To limit our analysis to newly-identified RA, we included patients with >1 year in the MSD cohort prior to RA diagnosis. To make our RA cohort as uniform as possible, we included only patients who first received a >90-day period of VA-prescribed MTX monotherapy. Kaplan Meier survival analysis and bivariate logistic regression were used to assess patient demographic and clinical data. After adjusting for significant predictor variables, we used a multivariate logistic regression to examine initial, non-MTX DMARD prescription by VISN.

Results:

A total of 4,823 patients (91% male, median age 64yrs, median observation time 3.91 yrs) met our inclusion criteria. All 21 VISN areas were represented (mean number of RA patients per VISN = 230 pts; range 88-488). Overall, 1,911 patients (40%) were prescribed only MTX monotherapy while observed in the RA cohort. Of the remaining patients who did receive a non-MTX DMARD, 748 (15%) went on to receive a bDMARD, whereas 2,164 (45%) received a cDMARD, as their initial, non-MTX DMARD prescription. The median interval between the first MTX prescription and initial, all non-MTX DMARD prescription was 1.13 years (IQR 0.56-2.25); a Kaplan Meier survival analysis did not show a significant difference between bDMARD and cDMARD interval prescription times (Kaplan Meier log rank p=0.94). Examining regional variation, 8 VISN areas were at statistically higher odds of receiving an initial bDMARD prescription, when compared to the VISN with lowest percentage bDMARD prescriptions (OR range 1.0-3.29, reference cDMARD prescription in VISN 23, see Figure 1).

Conclusion:

Following MTX monotherapy for newly-identified RA, we found a 3-fold variation by VISN in the prescription of biologic versus conventional DMARDs (see Figure 1; base 1.0 [VISN 23] in blue, highest 3.29 [VISN 22] in red). Further work is needed to assess the causes of these differences.