Background/Purpose: Approximately one-third of RA patients were prescribed biologic (Bio) monotherapy (MT) i.e. without concomitant disease-modifying anti-rheumatic drugs (DMARD) (Yazici et al., 2008). The purpose of this abstract is to summarize characteristics associated with Bio MT and Bio combination therapy (CMB) initiation in a cohort of previously bio naïve and experienced RA patients in US and evaluate if previous treatments, increased availability of biologics approved for MT after 2006, and individual physician-prescribing patterns influence the decisions to initiate Bio MT and Bio CMB.

Methods: Data were obtained from the Consortium of Rheumatology Researchers of North America (CORRONA) registry, an independent prospective observational cohort with >30,000 RA patients enrolled from over 100 academic and private practices across the US. Odds ratios (OR) (adjusted and unadjusted) for initiating MT in Bio experienced compared to Bio naïve patients were estimated using logistic regression models. A Median OR to account for random effects from variation in individual physician’s prescribing patterns and the effect of the availability of more biologics approved for MT after 2006 were also estimated.

Results: Between Oct 2001 and Apr 2012, 9,905 CORRONA patients initiated biologic therapy for RA, of which 40% were previously bio naïve. Demographics and disease activity characteristics in the Bio naïve and Bio experienced patients respectively were as follows; age (years; mean±SD): 57±14 vs 57±13, females: 76% vs 81%, duration of RA (years; mean±SD): 8±9 vs 13±10, seropositivity: 75% vs 73%, and CDAI (mean±SD): 19± 14 vs 22± 15.

Of the 9,905 patients, 25% received Bio MT and 75% received Bio CMB. Among patients that were previously bio naïve, 19% initiated a biologic as MT whereas MT initiation rates for patients who had received one prior biologic was 29%; two prior biologics, 26%; and three or more prior biologics, 31%. Higher rates of MT initiations were observed with prior Bio experience (unadjusted OR 2.01 [95% CI 1.70, 2.37]). Higher proportion of patients starting their biologic therapy after 2006 received MT as compared to those who started their biologic therapy prior to 2006 but was not statistically significant (unadjusted OR 1.20 [95% CI 0.99, 1.45]).

In the multivariate model (Table 1), Bio experienced patients continued to be significantly more likely to receive MT as compared Bio naïve. Median odds ratio showing the effect of individual physician’s prescribing patterns on initiating bio MT was 2.40 [95% CI 2.08, 2.86].

Conclusion: Monotherapy remains a common strategy of biologic prescription to treat RA. Prior biologic experience and individual physician’s prescribing patterns were associated with increased likelihood of initiating a biologic as monotherapy warranting further investigation to understand factors influencing decisions to initiate biologic monotherapy.